Thesis Doctoral
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Browsing Thesis Doctoral by Subject "Animal Management"
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Publication Open AccessThesis DoctoralBehavioural mechanisms of diet selection by horses(2016) ;van den Berg, Mariette; ; Compared to ruminants little is known about how horses modulate food intake and link the sensory properties (e.g. smell, taste) of foods with its post-ingestive consequences (negative and positive). While it has been suggested that horse’s foraging preference may be largely influenced by sensory input (e.g. volatiles, taste), because of hindgut fermentation, it has been established that horses are able to differentiate and select familiar foods (e.g. concentrates and hay) based on the nutritional content. However, there is a lack of knowledge of behavioural mechanisms related to olfaction, gustation and somatic sensory perception and their effects on diet selection by horses. In particular little is known of how these mechanisms may operate in pastured environments where horses are often exposed to a variety of plant patches, including familiar and novel species that may differ in flavour, nutrient concentrations and plant toxins throughout the year. The aim of this thesis was to further develop an understanding of behavioural mechanisms influencing diet selection by horses and in particular to determine how they identify and select amongst a variety of foods (familiar and/or novel) using sensory perception and post-ingestive feedback. A series of experiments examined: (1) The selection of familiar and novel forages using a checkerboard design to simulate patch foraging conditions. As changes in dietary preferences are largely influenced by the nutritional requirements of the animal and palatability of a food, it was of interest to investigate the effect of the nutritional status (energy intake) on novel forage selection by horses; (2) The influence of orosensory (smell) stimuli and post-ingestive feedback in the recognition of novel foods by horses. This was achieved by assessing the acceptance of a novel food with a familiar odour or with contrasting crude protein levels; and (3) The influence of different food characteristics i.e. nutrients, odour and taste, on the voluntary intake and preferences of horses exhibited when a number of foods were offered simultaneously (i.e. Smörgåsbord). In each experiment between 11 and 16 horses of Thoroughbred, Standardbred or Australian Stock Horse breeds were used. The findings of this thesis suggest that horses can respond to the nutritional content of foods, even if these are novel. There was a greater acceptance and intake of novel foods that contained a higher level of crude protein, and energy intake seemed to have a lesser impact on the intake of novel foods. It was also observed that the acceptance and intake of a novel food was largely influenced by the orosensory characteristics (smell, taste, texture), and possibly an individual’s experience. The thesis also shows that horses display patch foraging behaviour sampling from all foods on offer. When familiarised with diets horses clearly rank these based on nutrients, followed by taste and then odour. Further studies should assess the adoption of multiple-choice tests and nutritional geometric models to enhance our understanding of diet selection patterns by horses in different environments. In particular how individual animals may regulate the intake of multiple nutrients to meet dietary requirements. Whilst macronutrients may be the main driver for diet selection - the impact of the sensory perception on diet choice cannot be disregarded. This thesis highlights that familiar odour and taste cues could be applied in equine feeding management to increase food acceptance when forages/foods are scarce, during introduction of new foods or forage batches or when horses are moved to different environments.4156 1156 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralBody Weight, Flock Uniformity, Production Performance and Egg Quality over the Laying Period of Brown Egg-Laying Hens(2016) ;Suawa, Elfira Kariane ;Roberts, JulieParkinson, GregGenetic selection of laying hens has produced lighter body weight while maintaining maximum egg production. Heavy birds have problems during the laying period such as fatty liver and large size egg. The body weight at point of lay and flock uniformity can be used to predict the production performance during the laying period. However, there is evidence that hens which are overweight produce poor quality eggs during the laying period. The first two studies were conducted to investigate the importance of body weight at point of lay and flock uniformity on eggshell quality and production performance on commercial farms, both cage and free-range production systems. A laboratory experiment was then set up using the information derived from the on-farm studies, and extended to analyse body conformation using computed tomographic scanning. The body weight and flock uniformity in the on-farm studies varied from farm to farm. The poor performance of many of the flocks also illustrates the likely variation occurring at a commercial level; poor compliance with average growth rate patterns and low uniformity standards. Hen age had the greatest effect on most egg quality variables. In the laboratory experiment, flock uniformity prior to point of lay was designed to be above the breeder standard. Body weight at point of lay significantly affected egg production and eggshell quality. However, there was no significant effect on bone breaking strength and bone dimensions. Body weight was significantly correlated with the composition of lean, fat and bone. Heavy hens deposited more fat than lean tissue. Body weight should be maintained at the level of breeder standards. Correct body weight and high uniformity of the flock at point of lay will result in good performance over the laying period with high peak production and good persistency of production and the production of good quality eggs. Management is the key factor to regulation of body weight during rearing and at point of lay.3949 2032 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralCan sheep alleviate pain through free choice of medicated feed?(2017); ; ; ; Petherick, CarolThe focus of this thesis was to look at alternative pain-relief options for sheep with the possibility of an easy application method by providing analgesics in feed. Furthermore, if sheep can be taught to self-select and self-administer feed containing analgesics, it can provide insight into animal pain states. In order to understand why medicating livestock for pain is important, Chapter 1 provides an introduction into pain in livestock and its impact on their welfare.3902 780 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Cattle Temperament and Stress-Responsiveness in Relation to Productivity, Efficiency and Beef Quality(2011); ;Greenwood, Paul; Geesink, GeertThis thesis reports the results from two experiments studying aspects of temperament, productivity, beef quality and stress physiology in cattle, and their relationships with other production factors. Chapter 1 provides an introduction to the field of study covered by the thesis. Chapters 2 to 6 are presented as peer reviewed publications from the experimental work conducted. Chapter 7 presents a combined discussion and conclusions from the experimental work. A list of references appears as a part of each experimental chapter, and a consolidated reference list is provided at the end of the thesis (Chapter 8).1514 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Control of necrotic enteritis in poultry production with in-feed antibiotic alternative strategies(2017); ;Swick, Robert A; Poultry necrotic enteritis (NE) is caused by a Gram-positive bacteria, 'Clostridium perferingens' (Cp) leading to devastating economic losses in the broiler chicken industry. The aim of this project was to develop dietary strategies to control NE in broiler chickens as an alternative to the use of in-feed antibiotics. Four experiments were conducted to investigate the roles of four test articles in controlling necrotic enteritis in broilers, following the logic flow of NE pathogenesis. Predisposing factor: The first experiment was designed to test if glycine supplementation (10 g/kg) in grower diets could replace 'Eimeria' co-infection in establishing a subclinical NE challenge model, because dietary glycine has been shown to promote the proliferation of Cp. In this experiment, a successful subclinical NE challenge was achieved, as shown by a lack of mortality but mild intestinal lesions and higher feed conversion ratio (FCR) in the Cp challenged birds. A combined challenge with Cp and 'Eimeria' presented reduced body weight gain in broilers, whereas feeding supplemental glycine resulted in increased growth performance. The highest jejunal lesion scores were found in birds with a combination of Cp challenge and supplemental glycine without 'Eimeria' among all the treatments. The first study suggested that using glycine can partially replace 'Eimeria' in a subclinical NE challenge model in promoting intestinal lesions, but not impairing chicken performance. Gut microflora management: The second experiment was designed to determine the effects of a prebiotic, yeast cell wall extract (YCW) derived from 'Saccharomyces cerevisiae' or in-feed antibiotics, Zn bacitracin and salinomycin (AB) on broiler growth, intestinal lesions, humoral immune response and gut microflora metabolites during subclinical NE challenge. The results obtained in this experiment showed that AB siginificantly alleviated the impacts of subclinical NE on performance and intestinal lesions of broiler chickens, but YCW showed limited effects. Inclusion of YCW in diets suppressed the inflammation caused by NE and promoted the production of immunoglobulins on d16, indicating its immunomodulatory effects. For short chain fatty acids (SCFA) profile in cecal contents, YCW increased formic acid concentrations during challenge and increased butyric acid concentration in unchallenged birds on d16, implying a role in altering gut microflora metabolites. This study indicates YCW may not fully replace in-feed antibiotics in controlling subclinical NE in broiler chickens however it modulates immune responses and increases short chain fatty acid production, suggesting potential benefits to bird health. Anti-inflammation: A third experiment was conducted to investigate the effects of isoquinoline alkaloids (IQA) derived from Macleaya cordata as anti-inflammatory agents on broiler performance, intestinal lesions, productive traits, gut microflora, SCFA and serum biochemical indices during NE challenge. The effects of NE on broiler performance, carcass traits and intestine lesions were significantly alleviated by including IQA in the diets. Challenge with NE altered the serum biochemical indices, whereas IQA retained triglyceride and triiodothyronine levels on d16 and increased the total cholesterol and triiodothyronine levels on d24, indicating IQA controlled the pathophysical changes of NE challenge. This was most likely related to a direct anti-inflammation effect from IQA, because no differences in gut microflora or SCFA production in chicken were detected as a result of dietary inclusion of IQA. Compensating the metabolic loss from inflammation caused by NE: A fourth experiment investigated if supplemental L-glutamine (L-Gln, 10 g/kg) could reverse the negative impacts of NE on broiler performance, intestinal morphology and lesions and serum biochemical indices. Similar to IQA, results obtained in this experiment showed L-Gln significantly increased performance and intestinal development in broiler chickens during NE challenge. However, the mode of action could be different from IQA, as L-Gln did not affect serum biochemical indices, except that it decreased uric acid levels on d24. This indicates that L-Gln could have compensated for the metabolic loss from NE challenge, provided fuel to enterocytes and increasing amino acid utilization, rather than suppressing inflammation directly. The results of these studies suggest potential dietary strategies to control NE challenge in broiler chickens. The work highlights the importance of inflammation during NE infection and indicates inflammation should be a possible target for the future development of antibiotic alternatives and nutritional strategies to enhance gut health.2312 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Determinants of Australian Consumer Meat Demand(2018-10-26) ;Tighe, Kara; ; ; Ball, AlexanderOver the past two decades Australian meat consumption patterns have shifted away from red meat consumption and toward chicken and pork consumption. Inspection of relevant price and consumption data appears to explain the shift. However, the magnitude of relative price changes for each meat, in addition to the large body of literature dedicated to aggregate Australian meat demand, may indicate that non-price and non-income factors have contributed to the changes in consumer preferences over this period. This thesis provides the first known application of the generalised almost ideal demand system (GAIDS) to Australian meat consumption data to test for the existence of pre-committed (non-price and non-income driven demand) meat consumption among Australian consumers. A range of GAIDS model specifications are estimated to empirically test for the impact of non-discretionary demand shift factors on Australian meat demand, and to investigate alternative and novel methods of demand-shift index construction. Non-discretionary demand shift factors incorporated into the GAIDS include seasonal and time trend factors, and consumer interest in farm animal welfare, improvements in lamb eating quality, and lamb advertising campaigns. Attention is dedicated specifically to the determinants of Australian consumer lamb demand via the incorporation of the lamb eating quality assurance and advertising indices into the GAIDS, and an assessment of the determinants of Australian consumer willingness to pay for quality graded lamb. Evidence is found for the existence of pre-committed chicken consumption among Australian consumers when jointly estimated with seasonal and time trend factors. Results from this thesis support improved demand modelling of Australian meat consumption using the GAIDS; demonstrate the potential usefulness of alternative demand-shift indices; lend support to the notion that the lamb quality assurance program may have prevented larger falls in lamb consumption and expenditure; and highlight the critical requirement of data quality. Recommendations are provided for a more formal approach to GAIDS model development and specification when dealing with underlying data issues.
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Publication Open AccessThesis DoctoralEconomic assessments of practices and policies to address climate change and sustainable development for agriculture at global, regional and farm population scales(2018-08-27) ;Henderson, Benjamin B; The objective of this thesis is to address knowledge gaps, which can assist policy makers in preparing the agriculture sector for the challenges of addressing climate change. A range of methodologies are employed at different scales for these purposes. These include a global bioeconomic analysis and a global computable general equilibrium model to assess the global scale abatement potential of the ruminant sector (inclusive of cattle, sheep and goats), and the economic consequences of policies employed to achieve this potential. With the inevitable emergence of climate change policies and growing consumer expectations for improved environmental performance, these global analyses reveal that there is reasonable potential for the ruminant sector to contribute to global greenhouse gas (GHG) mitigation efforts, with the associated effectiveness and economic impacts varying widely depending on the choice of policy. The global scale analyses are complemented by a range of modelling assessments at the region and farm population scale in different smallholder production contexts, which reveal that there are also opportunities to exploit synergies between agricultural development, and climate change mitigation and adaptation objectives. It should be noted, however, that the global scale models are not formally linked to the smaller scale models (i.e. changes in the price and quantity variables in the global models are not used to update any of the variables in the smaller scale models).
It was shown that the global abatement potential for the ruminant sector indicated by the marginal abatement cost curves constructed in this thesis, could be substantially amplified by a global carbon tax. However, due to its disproportionately harmful impacts on ruminant production in low income countries, the overall merit of this policy option is questionable. In contrast, the use a producer subsidy to compensate producers for their tax expenses could effectively address these issues, albeit for a much reduced global mitigation potential. Another key insight of this research is that a carbon tax could restructure the global cattle sector, increasing the share of cattle meat supplied by the dairy sector relative to the beef sector.
Closing yield gaps for mixed smallholder farmers in several parts of Sub Saharan Africa, without the introduction of new technologies, could provide marked benefits for smallholder incomes and food supply, and reduce GHG emission intensities of production. Similarly, the intensification of beef production in Eastern Indonesia with improved feed from tree-legumes could deliver large increases in production and smallholder incomes and also lower the emission intensity of beef products. This innovation also has good potential for scaling up and is likely to benefit multiple value chain participants. It was also found that the costs of climate change could be partially offset by interventions based on increased fertilisation and the retention of crop residues for a population of mixed smallholder farmers in Sub Saharan Africa. Significantly, vastly different conclusions about the economic desirability of these practices were apparent when assessing their performance through the lens of the aggregate population, compared to considering the impacts on individual farms within the population.
Despite the large variation in scales and methods utilised in this thesis, a number of cross-cutting themes emerged from the analyses. For instance, the economic advantages of targeting sectors and producers with practices that can contribute to climate change mitigation and adaptation for the least cost or highest return, were apparent at different scales of analyses. Related to this, positive synergies between producer profits and mitigation or adaptation outcomes were also found across the analyses, for a range of improved practices and policies. Further, benefits from the integration of crop and livestock enterprises were apparent in the different analyses, although some practices were shown to generate trade-offs between these enterprises. Finally, all the studies in this thesis touched upon the challenges associated with barriers to the adoption of improved practices.3778 419 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralThe effect of dietary supplementation of calcium pidolate with or without vitamin D metabolite on production performance and egg quality in commercial laying hens(2016) ;Al-Zahrani, Khalid Salem ;Roberts, Julie RTwo experiments were conducted on commercial layer hens to study the effects of dietary supplementation with two levels of 25-hydroxycholecalciferol (25(OH)D₃) and two levels of calcium pidolate (with or without 25(OH)D₃) on production performance and egg quality. Experiment 1 was conducted using 90 Hy-Line Brown layer hens from 19 to 80 weeks of age and commenced in November 2012. Birds were divided into three groups of 30 hens as follows: group A (control group) fed with normal commercial layer mash feed, and groups B and C (treated groups) fed with normal commercial layer mash feed plus 0.5 g of 25(OH)D3 [premix (68.9 μg 25(OH)D₃)] per kg of feed and 1 g of 25(OH)D₃ [premix (137.8 μg 25(OH)D₃)] per kg of feed, respectively. Experiment 2 was conducted using 147 Lohmann Brown layer hens from 21 to 80 weeks of age and commenced in March 2014.4146 1226 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Effects of dietary minerals on phytase activity and nutrient utilisation of broiler chickens(2017-04-18) ;Akter, Mst Marjina; Hadden, GrahamThe major objective of this doctoral research project was to investigate the influence of varying levels of dietary minerals (Ca, NPP, Na, Fe and Zn) on phytase activity and its subsequent impact on broiler chickens. Along with an extensive review of literature (Chapter 2) related to this subject, the key findings of one in vitro study followed by four feeding trials are summarised in this thesis. Diets of all feeding trials were formulated by considering mineral matrix (Ca, P and Na) value of tested phytase and this matrix value appeared to be correct on the basis of the overall results of all trials.
In the in vitro experiment, the effect of different dietary minerals (Ca, Na, Fe and Zn) on phytase activity at different pH was examined (Chapter 3). Calcium (0, 0.6, 0.8 and 1.0 %), Fe (0, 70, 80, 90 mg /diet), Zn (0, 30, 40, 50 mg kg/diet) or Na (0, 0.15, 0.25 and 0.35 %) were incubated (30, 60 and 90 mins) with a Na-phytate (0.27 %) solution, with phytase enzyme (500 FTU kg/ diet) at pH 2.5 or 6.5. There was a reduction (p < 0.05) in phytate hydrolysis by phytase at high concentrations of Ca, Fe and Zn (10 g, 90 and 50 mg respectively), particularly at pH 6.5. Although, increasing Na concentration reduced (p < 0.05) phytate hydrolysis, mostly at pH 2.5, the pattern was indefinite. In the presence of high concentrations of Ca, Zn and Fe, residual phytate content after phytate digestion was higher (p < 0.05) at pH 6.5 than 2.5, while the reverse was the case in the presence of Na. The findings of this in vitro study was further evaluated in four subsequent feeding trial.
The influence of different levels of Ca (0.6, 0.8 and 1.0 %) and NPP (0.3 and 0.4 %) with phytase (500 FTU/kg) or without phytase supplementation was evaluated in first feeding trial (Chapter 4). In general, phytase supplementation improved (p < 0.05) the body weight gain (BWG), feed intake (FI) tibia bone breaking strength (BBS), tibia ash content, ileal digestibility of Ca, P and protein. However, the positive effect of phytase on these variables was reversed (p < 0.05) in diets containing high Ca (1.0 %) and low NPP (0.3 %). This combination of minerals and phytase also reduced (p < 0.001) the activities of alkaline phosphatase (AP), Ca-ATPase and Mg-ATPase activity of jejunum. High Ca diet reduced the carcass yield of bird even with phytase supplementation (Ca × phytase, p < 0.041).
In Experiment 3 (Chapter 5), the effect of dietary Na (0.15, 0.25 and 0.35 %) on phytase (500 FTU/kg) activity and broiler performance was evaluated and presented. Varying levels of dietary Na, phytase and their interaction did not statistically affect the performance and tibia bone development. High dietary Na (0.35 %) reduced (p < 0.001) excreta dry matter (DM). The ammonia excretion was higher (p < 0.007) in phytase supplemented diets than unsupplemented diets. The negative effect of high Na diet on AME (apparent metabolisable energy), ileal digestibility (Ca and P) and the total tract retention (Ca, P, Na and Mg) of nutrients was countered by phytase supplementation. Supplementation with phytase increased (p < 0.05) the activities of Na-K-ATPase in the jejunum.
The activity of phytase in the presence of varying dietary levels of iron (60, 80 and 100 mg/kg) in broiler chickens was investigated in Experiment 4 (Chapter 6). The phytaseinduced improvement in BWG (p < 0.001) and FCR (p < 0.045) at d 35 was significantly reduced by high dietary Fe content (100 mg/kg), indicating significant interaction between Fe and phytase. The combination of high dietary Fe and phytase also reduced (p < 0.001) the ileal digestibility of N, P, Mg and Fe. The high Fe diet reduced the tibia BBS which was counteracted (p = 0.059) by phytase inclusion. High dietary Fe increased (p < 0.001) the deposition of Fe in tibia bone and liver. Phytase improved (Fe × phytase, p < 0.001) the activity of Ca-Mg ATPase, Ca-ATPase and Mg-ATPase in the jejunum when supplemented to diet containing 80 mg Fe/kg.
In the final experiment, the response of birds to different levels of dietary Zn (30, 40 and 50 mg/kg) supplemented with phytase were assessed and presented in Chapter 7. The low Zn (30 mg/kg) diet reduced (p < 0.041) FI but only during 1-10d. Irrespective of Zn level, phytase supplementation improved (p < 0.012) the BWG at 1-24d. Bone development of birds was not affected by Zn, phytase or their interaction. Phytase supplemented to low Zn diet improved (p < 0.001) the ileal digestibility of P but reduced (p < 0.05) the Fe and Zn digestibility. The accumulation of Fe (p < 0.001) and Zn (p < 0.002) in liver was increased in birds on high Zn (50 mg/kg) diet. Phytase supplemented to diet containing 40-50 mg Zn/kg improved (p < 0.008) the net energy for production (NEp) and the fat and protein deposition rate in the tissues of broiler chickens. The activities of AP, Ca-ATPase and Mg-ATPase in jejunal mucosa was high (p < 0.001) in birds on the phytase-supplemented mid-Zn diet.
In general, it can be concluded that high Ca and Fe had significant negative effect on phytase activity and subsequently on broiler performance. The inhibitory effect of high Ca on phytase activity was more pronounced in low NPP diet. Phytase supplemented to high Zn showed better effect on birds’ performance. The negative effect of high Na only observed on utilization of some minerals and N which was countered by phytase supplementation. Finally, a careful consideration of dietary mineral levels in phytase supplemented diets can be a useful way to sustain the activity of phytase, improve productivity and reduce mineral excretion into the environment.
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Publication Open AccessThesis DoctoralFactors influencing the motivation of sheep for food(2013) ;Doughty, Amanda Kirstan; ; Matthews, LindsayThe measurement of strength of motivation is a tool used to assess the resources that an animal values and, subsequently, may aid in determining its welfare. However, the relationship between animal motivation and welfare is not well defined, with conclusions based on the assumption that welfare is reduced if a 'valued' resource is not provided. One possible way to better understand the relationship between changes in motivation and welfare is by investigating the factors that influence motivation in a demand test. This may provide a better understanding of motivation and may assist in elucidating the implications of changes in motivation on welfare and welfare assessment. Therefore, this thesis aimed to investigate factors that may alter the motivation of sheep for food in a behavioural demand test. Mature Merino wethers were trained in a 50m U-shaped lane to access a double-sided feeder and earned a food reward with each access event. Three different experiments were undertaken examining the effects of: 1) energy balance (comparing a 0h and 14h food deprivation); 2) energy density (comparing motivation for a high energy and low energy food) and; 3) the opioid reward system (comparing motivation for a high energy and low energy food with and without the administration of an opioid antagonist) on a ruminant's motivation for food. In each experiment either 8 or 10 sheep were tested to see how many times in a 20h period they would walk various distances (costs) for a 4g food reward after exposure to differing treatments. The main results indicated that energy balance (the difference between energy expended and energy consumed) may aid in determining feeding motivation at costs of 25m and less. However, no sheep stopped working for food at or near the point of zero energy balance (where energy consumed equals energy expended) and all sheep consistently worked for food at longer costs while in an energy deficit.3333 893 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralThe Impact of Some Management Stressors on the Acute Phase Protein Haptoglobin in Beef Cattle(2008) ;Slocombe, Lysandra; Assessment of the response of cattle to stressors has previously relied on behavioural changes and physiological responses, in particular cortisol concentrations. This thesis examines the impact of some management practices on the acute phase protein, haptoglobin, in beef cattle. Haptoglobin is readily measured in plasma using a biochemical assay of the peroxidase activity generated by the binding of haptoglobin to haemoglobin. It was found that the accuracy of this method was reduced by haemolysis occurring at the time of blood sampling. The assay presented in this thesis used the peroxidase nature of the haemoglobin-haptoglobin complex in the presence of hydrogen peroxide to catalyse a redox reaction which results in a chromogen changing colour. The assay is highly repeatable (92%) and robust. A correction equation was developed to adjust estimated haptoglobin values for the effect of haemolysis caused at the time of blood collection. The correction equation incorporated measures of plasma haemoglobin concentration and endogenous peroxidase activity present in the sample. Two sites commonly used in cattle for collection of blood samples are the jugular vein and coccygeal vessels. The impact of blood collection site on haematological variables and haptoglobin was examined. Total white blood cell count, lymphocytes, basophils, red blood cells and platelets differed significantly (P<0.05) between the two sites. Basophil counts had a higher concentration in blood collected at the tail. The other variables that significantly differed were lower in the tail vessels compared to the jugular vein. Haptoglobin concentrations did not differ (P>0.05) between blood samples from the two sites. The effect of the production stressors; weaning, transport; intensive management; muscle biopsy and social re-grouping on haptoglobin were analysed.1673 338 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Improving Performance of Free-Range Laying Hens(2019-02-11); ; Laying hens selected and bred for high performance in a controlled environment face various challenges when exposed to free-range housing systems. Gut impaction with grass, nutritional imbalances, and social stress such as feather pecking are some of the major challenges that the modern free-range egg industry in Australia is facing. The research subject to this thesis aims to improve the performance of commercial laying hens by comprehending the aforementioned challenges with the use of feed additives.
In this thesis, it was demonstrated that pasture consumption significantly (P < 0.05) reduced the digestibility of crude protein (CP), acid detergent fibre (ADF), neutral detergent fibre (NDF), insoluble arabinose and insoluble xylose. The digestibility of CP, ADF and NDF was significantly (P < 0.05) improved in hens fed a diet supplemented with multi enzymes (T2) or a diet supplemented with organic acid and essential oils (T3), compared to hens fed a control diet (T1). Similarly, hens fed the T2 diet had a greater digestibility (P < 0.05) of free oligosaccharides containing arabinose and xylose compared to hens fed T1 or T3 as discussed in Chapter 3. This higher digestibility of nutrients and non-starch polysaccharides can be linked to the heavier body weight of hens fed T2. In general, pasture consumption increased the body weight and egg weights of hens. However, non significant changes were observed on internal and external egg quality except a significant increase in yolk color colour score as a result of pasture consumption as discussed in Chapter 4.
The effect of pecking stones were tested in two commercial free range layer farms. On Farm A, using fixed sheds and flock sizes of 20,000 hens, access to pecking stones reduced (P = 0.001) hen mortality per week. Hens with access to pecking stones also had better wing feather conditions compared to hens of the control group (pecking stone × age, P = 0.002). These results provide evidence that access to pecking stones reduces feather loss and mortality. However, pecking stone consumption also caused hens to decrease large sized feed particles consumption and subsequently modified feed intake as discussed in Chapter 6.
The results of these experiments indicated that feed additives (dietary enzymes as well as freely available pecking stones) can be powerful tools to improve hen performance and welfare under free range conditions. In conclusion, the negative effects associated gut impaction, feather pecking in free-range hens' performance, health and welfare can be reduced with feed additives. However, further research is warranted to establish the role of various feed additives in freerange layer diets on commercial farms.
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Publication Open AccessThesis DoctoralImproving the effectiveness of gastrointestinal nematode control for meat-breed lamb production systems on the Northern Tablelands, New South Wales(2016) ;Dever, Michelle Louise; ; Walkden-Brown, Steve WThe experiments reported in this thesis were designed to define and improve the effectiveness of ewe and lamb gastrointestinal nematode control in meat-breed production systems in a summer-dominant rainfall region of NSW Australia. The experiments (Chapters 2-7) reported in this thesis were written as a series of publications. The first step in defining the effect of gastrointestinal nematodes (GIN) on meat-breed lamb production under grazing conditions is the creation and maintenance of uninfected control groups. Experiments conducted under grazing conditions are challenging with difficulties encountered in maintaining uninfected control groups as GIN-free. One method is to serially treat sheep with a combination of short and long-acting anthelmintics to provide effective and continual GIN-suppression.3932 792 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Improving the Nutritional Value of Cottonseed Meal for Broiler Chickens(2018-04-14); ; The commercial poultry industry is considered the most rapidly growing of all the agricultural sectors. Feed costs constitute around 70% of the total cost of poultry production. The most important feed ingredients for poultry production are energy and protein sources. The poultry industry mainly relies on a limited number of animal and vegetable protein ingredients, such as oilseed meals, legumes and animal by-products (Broomhead, 2013; FAO, 2013). The commonly used animal protein sources such as blood, meat, meat and bone and fish meals are recognized as high- quality protein, with excellent nutritive value and balanced amino acids. Furthermore, chickens tend to prefer animal by-products to vegetable proteins (Hossain et al., 2013). On the other hand, there are some constraints to the use of animal by-products as feed ingredients for animals; high prices, restricted hygienic conditions and the risk that birds may suffer from zoonotic diseases if the animal by-products are processed under sub-optimal conditions. Therefore, for ethical and/or health reasons, animal proteins are excluded from production systems in some parts of the world such as the European Union (Hamilton, 2002).
There are numerous vegetable protein sources of local importance around the world, such as soybean, canola, cottonseed, sunflower seed, peanut, and sesame meals, but these have less nutritive value than animal protein sources (Hamilton, 2002; Aftab, 2009). Most of the vegetable protein sources contain one or more anti-nutritive factors, which can limit the digestion of their nutrients and eventually affect overall animal health, for instance trypsin inhibitors, glucosinolates, and gossypol in soybean meal, canola and cottonseed meals, respectively (Akande et al., 2010). The average crude protein content of different vegetable protein sources ranges between 235 g/kg in peas and 480 g/kg in soybean meal (SBM). Soybean meal is the primary plant protein source used by the poultry industry around the world. However, canola meal (CM) is increasing in importance (Hamilton, 2002; Nagalakshmi et al., 2007). The price of both soybean and canola meals do fluctuate but are generally high, particularly in importing countries. Besides CM, there are other vegetable protein sources close to SBM in nutritive value, low in prices and locally produced such as cottonseed meal (CSM) and sunflower seed meal (SFM).
Cotton (Gossypium), a genus of the Malvaceae family, covers approximately 2.5 % of the agricultural land around the world. Cotton production worldwide is estimated as 23013 thousand tonnes. The highest cotton producing countries in 2015/2016 were India, China, United States, Pakistan, Brazil, Uzbekistan, Turkey and Australia with 5748, 4790, 2806, 1524, 1285, 827, 577 and 566 thousand tonnes, respectively (USDA, 2017).
Cotton yields a number of by-products which are of great value to humans and domesticated livestock. Cottonseed is one of the most valuable by-products produced after the fine cotton fibres are harvested. Jones (1985) reported that for each kg of fibre produced there is 1.5‐1.7 kg of cottonseed separated out in the ginning process. Cottonseed meal or cake is a by-product of oil extraction from cottonseed. It has been reported that crushing one tonne of cottonseed produces around 200 kg of oil, almost 500 kg of cottonseed cake and 300 kg of cottonseed hulls or exteriors (Campbell et al., 2009). Several factors affect the quality of cottonseed obtained, including genetic differences, environmental conditions and harvesting techniques, which indirectly affect the composition of the resulting cottonseed meal. In addition to the genetic differences and environmental effect, the differences in the produced cottonseed meal arise from the residual oil content due to the method of extraction. For this reason there are different types of cottonseed meals, in terms of their protein, fibre and oil contents. The three main methods used by the oil industry to extract oil from oilseeds are: mechanical, solvent and pre-press solvent extraction. Mechanical extraction is the traditional method; it uses a circular motor and hydraulic press or expeller. In this method the seed may need to be decorticated, dried and/or heated before extraction. Besides the cakes produced by this method being tough and large, another important disadvantage is that around 20% of oil remains inside the meal. This high amount of oil, although it considered as valuable energy source, but it may increase the cost and reduce the palatability and storage period of diets. The difference between the mechanical method and the direct solvent extraction method is that in the latter method the oil is extracted by solvents (hexane or ethanol) alone without mechanical pressing and the meal produced has lower oil content. The third method, the pre-press solvent extraction, was developed from a combination of the preceding two methods. This method is considered an integrated method because screw-pressing is followed by solvent extraction, resulting in the extraction of almost 97 % of the oil content of oilseeds (Morgan, 1989; Ash, 1992; O'Brien et al., 2005).
Cottonseed meal is a palatable and excellent source of protein for ruminants. Although it's nutritive value is less than SBM, but its low cost in some regions makes it the main source of protein for cattle especially in parts of India, Australia and United States. Furthermore, CSM can replace all other oilseed meals in dairy cow feeds without affecting milk production (McGregor, 2000). Using whole cottonseed as a major source of protein has been tested to some extent in large animals, but its use in poultry diets as such results in decreased feed consumption and conversion, reduced nutrient digestibility, and poor growth (Devanaboyina et al., 2007). Furthermore, incidence of lameness and a high mortality rate are also associated with feeding entirely CSM as a source of protein to birds (Kakani et al., 2010). The presence of anti-nutritional factors such as gossypol and cyclopropenoid fatty acid, high fibre content and a deficiency in lysine are the well-known factors that limit the use of CSM in poultry diets (Swiatkiewicz et al., 2016). Cottonseed meal has a high crude protein content that ranges between 220 g kg-1 in the in the non-decorticated and 560.2 g kg-1 in the completely decorticated seed, with metabolizable energy in the range of 7.4 to 11.99 MJ kg-1. Furthermore, the fibre content of CSM exceeds that of SBM by 25% in the non- decorticated to 5% in the fully decorticated seed (Nagalakshmi et al., 2007). This promising nutrient profile of CSM, along with the fluctuation in the price of SBM around the world encourages poultry nutritionists and producers to trial CSM as a cost-effective and best nutritional alternative to SBM (Aftab, 2009).
Numerous ways have been reported that help in alleviating the limitations associated with the inclusion of CSM in poultry diets and raise its nutritive value. These include genetic manipulation of Gossypium through conventional breeding approaches and/or modern biotechnology, ingredient processing, using effective feed processing techniques, to decrease and inhibit anti-nutrients, and supplementation with nutrients such as synthetic amino acids, fat and vegetable oils. However, microbial enzymes appear to be the most effective solution to overcoming the limitations of the high-fibre and the non-starch polysaccharide (NSP) contents of alternative vegetable proteins that limit their inclusion at high levels in poultry diets (Scott et al., 1998: Leeson and Summers, 2001). All the above-mentioned techniques have helped to increase the CSM inclusion rate from 5% to around 30% of complete formulated diets for broiler chickens without compromising birds' performance (Watkins et al., 1995). Poultry lack specific enzyme systems to target NSP. For this reason, researchers are concentrating on developing single and composite microbial enzyme products that target NSP and enhance the nutritive value and nutrient digestibility of diets containing fibrous vegetable protein meals (Scott et al., 1998).
The poultry industry has employed microbial enzymes to improve the quality of temperate cereals and oilseed cakes. Therefore, inclusion of appropriate exogenous microbial enzymes in poultry feeds has clearly been demonstrated to increase the bio-availability of poorly digested diets, promote utilization of fibrous diets and improve the feed conversion ratio. These positive effects of the usage of exogenous enzymes have been frequently reported in recent studies as a result of the use of newly developed products for specific ingredients (Creswell, 1994; Slominski et al., 2006; Raza et al., 2009).
Much research and many industry field studies have been conducted to investigate the possibilities of replacing more expensive plant protein sources, like SBM, with alternatives with a similar nutritive value but lower prices such as CM, CSM and SFM. The present study is one of these investigations, and, hence, the main objectives of this study are to:- Test the response of broiler chickens to CSM-containing diets supplemented with new microbial enzyme products (Avizyme 1502 and Axtra XB).
- Assess the potential of microbial enzymes in improving the nutritive value of CSM in diets for broiler chickens, especialy NSP-targeting enzymes.
- Evaluate CSM as a cost-effective alternative protein ingredient to SBM without compromising broiler performances.
- The study is intended to, among other things, determine the optimum levels of CSM and the test microbial enzymes in diets for broiler chickens and establish CSM as a competitive alternative to SBM.
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Publication Open AccessThesis DoctoralIn-paddock walk-over weighing: understanding the factors affecting its potential for the Australian Sheep industry(2014) ;Brown, David James; ; Hatcher, SueThe association between liveweight and a range of production and economic outcomes has been demonstrated in sheep production systems. Change in ewe liveweight affects her wool production, reproductive performance, survival and lifelong performance of her progeny. Similarly, liveweight in young sheep post-weaning is strongly associated with their survival. This breadth of sheep production parameters with demonstrated association with liveweight suggests that regular liveweight monitoring would provide a robust and versatile tool for managing sheep flocks. Walk-over weighing (WOW) technology has the potential to remotely monitor sheep liveweight either individually or collectively and is commercially available. It functions by collecting liveweight data as sheep voluntarily cross a weighing platform as part of their normal daily routine. The liveweight data is then collected, processed and interpreted by livestock managers to aid nutritional management. Despite the documented benefits of managing ewe liveweight, and the potential of WOW to aid ewe liveweight management, there is a paucity of literature on the subject. This thesis draws on a series of experiments, data analyses and economic models to investigate the factors affecting WOWs potential for commercial application.3557 743 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Matching Genotypes with Feed Resources: Performance of female Holstein-Friesian and Ayrshire crosses under varying feeding regimes and production systems in Western Kenya(2015) ;Lukuyu, Margaret Nyawira; ; Greenwood, PaulSmallholder dairy production can be a powerful tool for reducing poverty, raising nutrition levels and improving the livelihoods of rural people in Kenya. For sustainable development of this important industry, promotion of genetic resources/breed types should be done with an understanding of the farmers' objectives and the limitations and opportunities of the production environment. To identify appropriate genotypes, the current study was conducted and it assessed the performance of dairy cattle with different levels of exotic genes in different production environments in Western Kenya. Feed intake and liveweight are critical factors in animal performance. The study therefore generated groundtruthing data that can be used to develop algorithms for estimating intake of individual grazing animals with precision. In addition, a model for estimating liveweight of dairy cattle under smallholder dairy context was developed.2378 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralMaximizing the nutritional value of unprocessed soybean meal through supplementation with complex microbial enzyme products(2017) ;Erdaw, Mammo Mengesha; This thesis presents findings of a comprehensive research project on the potential of raw soybean meal (RSBM) as partial replacement of commercial soybean meal (SBM) in diets for broiler chickens. There was an extensive review of literature on the subject, followed by one in vitro experiment and five feeding trials. The first experiment of this thesis (Chapter 3) investigated the physico-chemical properties of RSBM as a feed ingredient and the influence of the ingredient on the physical and chemical properties of broiler diets. The effects of heating (95⁰C) the soybean samples over different durations on the nutrient composition and concentrations of anti-nutritive factors (ANF) were assessed. The enzymatic in vitro digestibility of nutrients in the samples was also evaluated. The results of the in vitro study showed that heating the soybean samples at 95⁰C for up to 60 min was not sufficient to reduce the levels of ANF, particularly the trypsin inhibitors (TI). Replacing commercial SBM with RSBM (up 30%) in diets reduced the quality of the diets; for example, the urease activity (UA) and nitrogen solubility index (NSI) were increased. The in vitro digestibility of DM and CP as well as phytate were improved when the samples were incubated in a cocktail of protease and phytase compared to when these individual enzymes were used or not used. In addition to the pellet durability index (PDI), the effects of two pelleting methods on diets containing graded levels of RSBM were assessed in another experiment (Chapter 4). The concentrations of ANF, particularly TI and performance of birds were evaluated. Feed particle distribution and dietary electrolyte balance (DEB) were also investigated in this experiment. Steam-pelleting the diets containing high levels of RSBM improved the PDI, compared to cold-pelleting but the amino acid profiles were better in cold-pelleted and mash samples than the steam-pelleted diets. Increasing the level of RSBM, particularly replacing 30% of commercial SBM (9% of diet) reduced the feed intake (FI), body weight gain (BWG) and feed conversion ratio (FCR) of broilers when fed from one to 14 days of age. Birds fed on the steam-pelleted diets had reduced BWG. Increasing RSBM in diets affected the development of internal organs, particularly the weight of the pancreas and duodenum, which was increased. The response of broilers fed on cold-pelleted diets containing graded levels of RSBM (replacing 0, 10 or 20% of SBM) and supplemented with increasing levels of microbial protease is reported in Chapter 5. The gross response of the birds, in terms of FI, BWG, and FCR; development of internal organs, and meat yield were assessed. Furthermore, the activities of digestive enzymes, ileal nutrient digestibility, intestinal mucosal morphometry and concentration of DNA in the pancreas were also investigated in this experiment. Although the contents of ANF, especially TI exceeded the threshold level for poultry, the gross response (BWG, FI and FCR) of birds on the tested diets was statistically similar to that of bids fed on the RSBM-free diets. These results may be in response to microbial protease supplementation, ameliorating the adverse effects of ANF, particularly TI. The activities of some digestive enzymes at 24 d of age, for example trypsin and chymotrypsin improved in response to protease supplementation. The apparent ileal digestibility (AID) of CP and amino acids (AA) were reduced with increased levels of RSBM in diets. These same parameters were further evaluated in another trial when diets contained a relatively higher level of RSBM (replacing commercial SBM at 25%) and extra-dosing with microbial protease and phytase (Chapter 6 of this thesis). Feeding the birds on diets containing this higher level of RSBM did not statistically reduce the gross response of broilers over 1-35 d, and these results further suggest the positive effects of extra-dosing of the diets with microbial protease and phytase. The villus height and crypt depth of broilers at 10 d of age were increased when the diets were extra-dosed with phytase. A preliminary cost-benefit analysis also showed that the use of the enzyme supplements even at extra-dose levels did not substantially increase the cost of the diets. The effects of the test ingredient (RSBM) on dietary protein utilization were evaluated in Chapter 7. This involved measurements of AID of protein and AA. Endogenous nitrogen secretion at the ileum was also measured and used to calculate the standardized ileal digestibility's (SID) of protein and AA. The test ingredient reduced both the AID and SID of protein and AA but these were improved by supplemental protease. The wellbeing of broilers, in terms of mortality, footpad dermatitis, intestinal lesions, tibia bone characteristics and litter quality were assessed and reported in Chapter 8. These traits were all not significantly different in chickens on the test diets compared to those on the RSBM-free diet. The concentrations of plasma myo-inositol, Na and Cl at 24 d of age were not affected by RSBM or protease supplementation. The results confirmed what was observed in previous Chapters in terms of productivity and health of the birds on the RSBM-containing diets. A major finding of this project is that although the dietary concentration of TI was substantially increased with increase in level of RSBM, there was no drastic impact on productivity or health of the birds. This may be due to the effect of the supplemental enzymes included in the diets. It can be concluded that RSBM could replace commercial SBM at levels beyond what was previously thought possible provided the diets are supplemented with appropriate microbial enzymes. The preliminary cost-benefit analysis of using RSBM indicate good returns but further studies are required into the behaviour of proteins in RSBM, especially in the presence of the test protease.4217 988 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralMethane Production and Productivity Changes Associated with Defaunation in Ruminants(2017-03-31) ;Nguyen, Son Hung; With increasing world population, global demand for a secure and growing food supply challenges the livestock producers of today to increase output of milk and meat while reducing the environmental impact of animal production. This thesis reports a review of literature and targeted new research assessing the consequences of eliminating rumen protozoa (defaunation) on the performance, digestive function and emissions of the greenhouse gas methane, by livestock.
• Comparative studies of rumen fermentation and animal growth were conducted in growing Merino lambs, crossbred sheep and Brahman cattle. In these studies ruminants were defaunated using coconut oil distillate to suppress protozoa then dosed with sodium 1-(2-sulfonatooxyethoxy) dodecane in a protocol that suppressed feed intake for an average of 10 days but had no detrimental effects on animal health.
• Reflecting the diversity in published literature, these studies found inconsistent effects of defaunation on volatile fatty acid (VFA) concentrations and proportions. Averaged over all experiments conducted, defaunation was associated with a small (5%) reduction in total VFA concentration and an increase (5%) in the ratio of acetate to propionate in the rumen.
• While effects on VFA were not consistent, an average 30% reduction in rumen ammonia concentration and a 16% increase in microbial crude protein outflow (estimated by allantoin excretion) were apparent, suggesting substantial differences in the ruminal degradation and outflow of protein due to defaunation. These changes were associated with an 18% increase in average daily gain (ADG), but surprisingly no increase in wool growth rate.
• Defaunation was associated with a lower enteric methane emission (average 20% reduction) compared to faunated ruminants, with the first studies of daily methane production (DMP) ever made while grazing, made using GreenFeed Emission Monitoring (GEM) units, confirming a 3% lower DMP (non-significant; P > 0.05) and a 9% lower methane yield (MY; CH4/kg DMI; P = 0.06) in defaunated sheep.
• Protozoa affected the rumen response to nitrate, with the nitrate induced reduction in MY being 29% greater in faunated compared to defaunated lambs.
• With dietary coconut oil, no interaction with defaunation was apparent with both coconut oil and defaunation significantly reducing DMP and MY in cattle.
• While defaunation tended to increase average daily gain and reduced enteric methane emissions in cattle by 10%, establishing defaunated cattle proved difficult and is a major constraint to expanding defaunation into commercial herds.
• Assessment of the distribution of protozoa in the forestomaches showed that the number of entodiniomorph protozoa attached to the 'leaves' of the bovine omasum was at least as great as the number attached to the entire surface of the rumen, though all tissue-attached populations are far fewer than the population in the rumen fluid.
• It is concluded that defaunation alone or in combination with dietary supplements of nitrate is effective in decreasing methane emissions, while increasing microbial protein supply and ADG. Commercial implementation of defaunation for cattle will not be able to rely on addition of surfactants to the rumen and it is suggested a bioactive compound distributed through the blood may be needed to remove protozoa residing in the omasum.3663 464 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralA Microeconometric Assessment of the Integrated Crop-Livestock Production Systems in Ghana(2016) ;Asante, Bright Owusu; ; Majority of Ghanaian farmers produce multiple commodities in integrated farming systems. These systems contribute significantly to Ghana's domestic food production and food security. However, most of these farmers receive very low returns from their farming activities making it difficult to sustain or improve household livelihoods. One reason for these low returns is the low productivity and low uptake of technologies in these farming systems. This leaves most farmers in great financial difficulty, particularly during the dry season where most crops are not supported by the climatic conditions. The production of crops, such as yam, cassava, maize, cowpea, groundnut and soybean, as well as livestock, such as small ruminants in a diversified system, are very significant to the livelihoods of the farmers by ensuring a stable income and employment of productive resources throughout the year. Previous studies have focused on the analysis of the patterns of adoption and performance of farmers in a single crop or livestock production system, but attempts to evaluate the performance in integrated crop-livestock systems are limited. This study fills this gap by using farm-level data collected from farmers in the Atebubu-Amantin and Ejura-Sekyedumase districts to evaluate the nature of adoption of improved technologies in key crops and livestock and integrated crop-livestock farming systems. The nature and determinants of diversification and the extent and drivers of productivity in integrated crop-livestock systems in Ghana are also examined.3838 883 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralNovel Probiotics for Broiler Chickens(2009) ;Olnood, Chen Guang; ; The purpose of this thesis was to select beneficial bacteria from the chicken intestinal tract and to screen them for their potential probiotic characteristics in order to use them against pathogenic bacteria, such as 'C. perfringens' and 'Salmonella'. Five experiments (Chapters 3-7) were conducted and out of four potential probiotic candidates, 'L. johnsonii' was eventually selected as a model organism and its effects on bird performance, gut microflora, gut morphology, and antibiotic effect were examined. Throughout this thesis, Cobb, male broilers were used. Each experimental chapter has been presented as a stand-alone paper, thus, this summary will only give an overview of the key findings of the thesis. Chapter 1 briefly describes the background information and justified the importance of research in the topic of interest, leading to the major hypothesis and objectives for conducting the five experiment contained in the thesis. Chapter 2, the literature review, covers the use of probiotics in poultry production, focusing on their modes of action and properties, and their potential as alternatives to in-feed antibiotics. In Chapter 3, four probiotic isolates were selected from 235 lactobacillus isolates of poultry origin using an antagonistic test against 'C. perfringens', 'E. coli' and 'S. sofia'. Quantitative and qualitative measurements revealed that these four candidates, 'L. johnsonii', 'L. crispatus', 'L. salivarius' and one unidentified 'L.' sp., were antagonistic towards 'C. perfringens', 'E. coli' and 'S. sofia' in vitro and were able to survive in feed for 7 days, in water and litter for more than 24 hours under practical production conditions. Chapter 4 presents data the efficacy of delivering 'L. johnsonii', 'L. crispatus', 'L. salivarius' and an unidentified 'Lactobacillus' sp. via feed in manipulating gut microflora environment and production performance was investigated. Results showed that none of the four candidates improved bird performance but they increased the small intestinal weight and tended to reduce the number of enterobacteria in the ileum. Among the four candidates, 'L. johnsonii' was the best in its effects on gut development and gut microflora, thus it alone was to be used in subsequent studies.1552 510 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralNutritional Manipulation to Minimise the Impact of Necrotic Enteritis in Broiler Chickens(2017-10-27); ; ; ; Svihus, BirgerNecrotic enteritis (NE) is an important poultry disease that is currently controlled by the use of in-feed antibiotics in many countries, including Australia. The general public demands clean and green poultry products that require the discontinuation of the use of antibiotics in feed. To achieve this goal, the broiler chicken industry must address the impact of NE without the reliance on in-feed antibiotics. The current thesis has examined a variety of nutritional strategies to minimise the impact of NE in broiler chickens using a subclinical NE model.
Chapter 1 presents the summary of literature related to NE with particular emphasis on the role of nutritional tools in alleviating losses associated with NE outbreaks. Chapter 2 examined the effect of early feeding a high amino acid density diet on performance of broilers under NE challenge. Birds fed the high amino acid diet had greater body weight by d 35 and heightened Lactobacillus content in the ileum at d 16 (P < 0.05). Birds that were fed the high amino acid (HAA) diet after a period of fasting post-hatch performed better regarding feed conversion ratio (FCR) performance under challenge. The findings from this study suggest there are beneficial effects of feeding high amino acid diets to birds in response to external stresses, such as post-hatch fasting and subclinical NE.
Chapter 3 investigated the effect of the reintroduction of crude ileal and caecal contents from previously NE-challenged chickens on performance, mortality and intestinal lesions of young broilers under NE challenge. Cloacal administration of both ileal and caecal crude flora inoculants significantly (P < 0.05) improved feed conversion efficiency and alleviated (P = 0.049) the severity of NE-associated lesions at d35. These preliminary findings suggest that the gut microbiome of birds plays a significant role in the susceptibility of broilers to NE.
Chapter 4 examined the prebiotic properties of arabinoxylo-oligosaccharides (AXOS) produced both in situ and in vitro for their activity against the onset of necrotic enteritis in broiler chickens. Birds fed the AXOS diet had numerically less severe gross lesions, improved feed conversion at d0-16 (P=0.043) and lower ileal viscosity (P < 0.001) at d16 compared to birds fed intact arabinoxylans. Caecal short-chain fatty acid (SCFA) concentration was higher in birds fed AXOS compared to other diets and was higher in the challenged birds compared to the unchallenged birds. The results suggest that AXOS appear to be efficacious prebiotics, as highlighted by improvements in feed conversion ratio (FCR) and increased SCFA.
Chapter 5 explored whether supplementing diets with xylanase, pectinase and protease would alleviate the effects of key predisposing factors of NE, xylans (from cereals), pectic polysaccharides (from vegetable protein sources) and undigestible proteins on bird performance, caecal volatile fatty acid concentration and ileal pH and prevalence of intestinal lesions, in NE challenged birds. The protease enabled higher weight gain compared to that fed xylanase at d0-35 (P=0.040) and d0-24 in the unchallenged birds (P<0.001). Feed intake was higher at d0-35 (P=0.001), and d0-24 (P=0.011) in birds fed protease, resulting in better feed conversion (P=0.009) in birds fed xylanase compared to that fed protease. Findings from this study suggest that enzyme application can be used as a tool to reduce the amount of undigested nutrients reaching the hindgut and hence lessen the growth of pathogenic bacteria.
Chapter 6 examined the effects of arabinoxylan (AX) and AXOS on net energy and nutrient utilisation in broilers. Ileal dry matter digestibility was higher in birds fed AXOS compared to that fed AX (P=0.047). Ileal digestible energy and total tract dry matter digestibility was higher in birds fed AXOS compared to that fed AX or AX+E (P=0.004 and P=0.001, respectively). Birds fed AXOS had higher ME intake (P=0.049) and nitrogen retention (P=0.001) and a strong trend of higher NE (P=0.056), NE intake (P=0.057) and retained energy (P=0.054) compared to that fed AX. Total ileal SCFA concentration, including lactic and formic acid, was higher in birds fed AXOS compared to that fed AX (P=0.011, P=0.012 and P=0.023, respectively). These findings indicate that AXOS generation in the gastrointestinal tract via the use of enzymes is not as efficient as feeding AXOS directly.2610 399 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralNutritional value of canola meal for broiler chickens as affected by processing conditions, microbial enzymes and essential amino acids(2016); ; ; Four experiments were conducted to assess the effects of processing conditions on nutritional value of expeller-extracted canola meal (ECM) and the replacement value of expeller and cold-pressed canola meals in broiler chicken diets. The first two experiments evaluated and characterized the effect of processing conditions such as conditioning temperature (90, 95 or 100 °C) and screw torque (high or low) during oil extraction process on apparent metabolizable energy (AME), apparent and standardised ileal digestibility of amino acids of ECM for broiler chickens. The values obtained in these two experiments were used to formulate diets with high inclusion of ECM to investigate the effect of a microbial multi-carbohydrase obtained by fermentation from 'Aspergillus aculeatus' (Ronozyme® VP), and a microbial mono-component protease (Ronozyme® ProAct), in diets on productive traits, nutrient digestibility and partitioning of energy in broiler chickens. The fourth experiment was designed to determine if reduced feed intake of birds fed CM-based diets, per se accounts for growth depression and if this retarded growth rate can be attenuated by increasing dietary digestible amino acid levels of the diet.3674 766 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Nutritive Value of Sorghum Grains in Diets for Broiler Chickens(2017-10-27); ; Gous, RobertDetailed findings of the potential use of sorghum grain in diets for broiler chickens are presented in this thesis. A comprehensive literature on the above subject was reviewed, followed by feeding trails.
An initial experiment (Chapter 3) in this thesis evaluated the chemical composition and nutritive value of South African sorghum varieties as feed for broiler chickens. Physical and proximate composition, total phenolic and antioxidant activity, mineral content, amino acid profile and digestibility and true metabolisable energy of four sorghum varieties were studied. The thousand-kernel-weight ranged from 33 to 28 g and kernel texture was somewhat corneous to floury. The condensed tannin sorghum varieties, PAN8625 and NS5511, had higher total phenolic content and antioxidant activity than the non-tannin varieties, PAN8816 and PAN8906. Starch and gross energy contents differed significantly across the sorghum varieties. The sorghum varieties had somewhat similar total and individual mineral contents. Threonine, leucine, phenylalanine, valine, proline and alanine contents of varieties PAN8625 and PAN8906 were higher than those of NS5511 and PAN8816, which had similar contents. The amino acid digestibility and metabolisable energy of the tannin sorghum varieties were generally lower than those of the non-tannin varieties.
In addition to determining the physio-chemical properties of sorghum grains the influence of xylanase inclusion in sorghum-based diets on performance of broiler chickens was determined in another experiment (Chapter 4). Gross performances were assessed and carcass yield and visceral organ weights were measured at day 21. On day 25, birds were euthanized by intravenous injections of sodium pentobarbitone, and digesta contents from the distal ileum were collected and processed to determine the nutrient digestibility. Broiler chickens offered sorghum variety Pan8816 supplemented with xylanase had higher feed intake, weight gain, and better feed conversion ratio (FCR) than those given diets composed of sorghum variety Pan8625 without xylanase addition at 1-7 days of age. Crude protein digestibility of Pan8625, a tannin variety not supplemented with xylanase, was lower than that with xylanase. Enzyme inclusion significantly increased the crude protein digestibility.
In Chapter 5 of this thesis the response of broiler chickens to whole sorghum inclusion and feed form were evaluated. Body weight and feed intake were measured on a pen basis at 10, 25, and 35 days of age and feed conversion ratio (FCR) calculated. Pellet diets affected feed intake, body weight and carcass parts of broiler chickens aged 1-35 days. Heavier relative gizzard weights with lower pH were recorded for broiler chickens offered mash diets at ages 1-35 days. FCR at 1-35 days increased with an increase in WS and levelled off with higher inclusion rates. Relative gizzard weights at 35 days marginally increased with the increase in whole sorghum inclusion levels. Similarly, relative bursa and liver weight at 35 days increased with the increase in WS inclusion. Overall, the results showed that pelleted diets were superior to mash diets. Although higher levels of WS inclusions enhanced the gizzard development, performance parameters of birds offered these levels were not affected.
The influence of age of introducing whole sorghum grain and xylanase supplementation to broiler chicken diets was evaluated in this thesis (Chapter 6). A whole sorghum inclusion level of 50 % with or without xylanase was offered to birds at different ages. Gross performance parameters on a pen basis at 10, 24, and 35 days of age were measured. Age of introduction had improved feed intake and body weight of broiler chickens at ages 1-10 and 1-35 days. Chickens offered whole grain from hatch had higher feed intake and body weight at 1-10 days. The relative visceral organ weights, meat parts yield, meat colour and pH were not influenced by age of WSG introduction or xylanase supplementation. Apparent metabolizable energy (AME) of diets and of the sorghum was improved by age of introduction. Birds to which whole grain was introduced from hatch or day 11 had significantly higher AME than birds not receiving whole grain inclusion. Age of introduction had an effect on gross performance of broiler chickens. Feeding whole grain as early as hatch marginally improved body weight and feed intake of broiler chickens.
The main finding in this thesis is that non-tannin sorghums fed to broiler chickens are superior to the tannin-containing varieties although the relatively high anti-oxidants activities of the latter may have health-promoting benefits. Feed form affected the performance of broiler chickens offered pelleted diets, resulting in better performance than mash diets. Whole sorghum grain inclusion level did not affect feed intake and body weight gain of broiler chickens; however, feed efficiency increased with an increase in whole sorghum. This indicates that WSG can be added to broiler diets at any inclusion rate without negatively affecting performance.
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Thesis DoctoralPublication Odour Emissions in Broiler Production: Influence of Nutrition, Necrotic Enteritis and Litter Condition(2017-04-18); ; ; Odour emissions have been identified as a potential threat for the sustainable development of the broiler industry. Few of the methods examined to reduce odour emissions from poultry operations have proved effective. The methods including biofilters, litter treatments, neutralising agents, air scrubbers, ozone treatment are either impractical to apply or too costly to use in commercial farms. If diets could be formulated to more closely meet nutrient requirements, there would be reduced excretion of undigested components and lower level of substrates available for microbes to metabolize them to odorous compounds. Diet affects water intake, water to feed intake ratio, litter moisture, litter pH and litter water activity all of which may have an impact on the emission of odorants from the litter. This thesis details the role of diet composition, necrotic enteritis and litter condition on odour emission from broiler production. This thesis includes a comprehensive review on key odorants from broiler production, their origin, analytical techniques for odour measurements and nutritional factors affecting odour emissions. The five chapters that follow investigate the role of phytase enzyme (chapter 2), protein sources (chapter 3), protein levels (chapter 4), probiotic and saponin (chapter 4), litter condition (chapter 4 and 5), necrotic enteritis and high sodium diet (chapter 5) and the effect of Clostridium perfringens culture (chapter 6) on odour emissions. Nutritional strategies such as increasing meat meal in the diet, decreasing dietary protein levels and the addition of a Bacillus subtilis based probiotic and saponin blend may lower odour emission from broiler production. The results also indicate that odour is related to litter condition and if litter moisture content and water activity can be reduced and necrotic enteritis prevented, odour problems can be alleviated in broiler sheds.
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Publication Open AccessThesis DoctoralOn-animal motion sensing using accelerometers as a tool for monitoring sheep behaviour and health status(2017); ; ; Dobos, Robin CAn opportunity exists to infer the physiological and physical state of an animal from changes in their behaviour. As resting, eating, walking and ruminating are the predominant daily activities of ruminant animals, monitoring these behaviours could provide valuable information for monitoring individual animal health and welfare status. Conventional animal monitoring methods have relied on visual observations of animals by human labour. This can only provide information on an animal's behaviour for the period in which they are being observed. Historically, observations could be made for long periods where shepherds were employed to observe their flocks nearly constantly. This is obviously no-longer feasible in the current livestock industry. Recently, with the advent of small, low power accelerometer technology, the ability to remotely monitor animal movement continuously has arisen. This is achieved through the application of on-animal inertia monitoring unit (IMU) sensors. This movement data might potentially lead to continuous behavioural monitoring of livestock. These devices have been developed for higher value livestock such as dairy cattle but little research or development has been directed towards their use in sheep. Previous work has evaluated collar and leg deployments however the sheep industry demands these devices be in an eartag form factor to align with current industry practices. Therefore, this thesis aims to evaluate the potential for using ear-borne accelerometer devices to detect and categorise key behaviours expressed by sheep. Deviation from normal patterns of behaviour may be used as an indicator of changes in individual health status. If behaviour can be categorised using the data collected by these body worn devices and radio telemetry incorporated, animal health could be monitored in near real time allowing early treatment intervention when necessary, ultimately improving on-farm productivity. Scoping work in this thesis identified the difference in acceleration signals between the basic sheep behaviours: grazing, walking and resting, giving potential for discrimination between behaviours with classification algorithms. Subsequently a successful behaviour classification algorithm was developed based on accelerometer data obtained from the ear deployment, yielding activity predictions similar to those obtained through visual observation. To apply this technology to a commercial application, a simulated lameness experiment was designed, where lame walking behaviour was discriminated from sound walking events successfully using the ear and leg modes of deployment. The final experiment investigated the application of ear deployed accelerometer devices to detect behavioural changes associated with increased infection by internal parasites, a disease of extreme economic importance within Australia. Animals with a higher faecal worm egg count were shown to have a lower probability of engaging in longer periods of activity, however this experiment was limited by a very mild level of infection. Overall this thesis demonstrates that sheep behaviour can be classified using an ear-mounted tri-axial accelerometer sensor, the first of its kind to date. It also explored the suitability of using time-series behavioural classification data as an early indicator of health and welfare issues. This work aims to link a previous "research only" technology in sheep, to a commercial application, a stepping stone towards bridging the gap between research and industry adoption.4948 2432 - Some of the metrics are blocked by yourconsent settings
Thesis DoctoralPublication Potential for Remote Monitoring of Cattle Movement to Indicate Available Biomass(2015) ;Roberts, Jessica Jane; ; ; ; There is a call for sustainable intensification of agricultural industries to cope with impending challenges to future food demand and production. Beef and sheep meat production in Australia is dominated by grazing production systems, and equates to the largest land use of the country. Pasture utilisation by livestock can be a major limiting factor in grazing production systems, through under- or over-grazing. This thesis aims to identify if spatio-temporal information from livestock tracking devices can be used to understand livestock-biomass interactions in a rotational grazing system. The specific goal was to determine if this spatio-temporal data might be related to pasture characteristics (particularly biomass quantity) and potentially used as an indicator of the state of the pastures being grazed. Cattle were tracked with GPS for detection and monitoring of specific behaviours including, distance moved, time spent grazing, stationary or travelling, spatial dispersion and social dispersion. Behaviours were compared with declining pasture availability, monitored with an active optical sensor. This thesis explores the behaviour of cattle in three grazing situations.2736 1 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralQuantifying effects of wild dogs, domestic dogs and humans on the spread of rabies in Australia(2016-10-22) ;Sparkes, Jessica Louise; ; ; Rabies is a preventable viral zoonosis that causes inflammation of the brain, and eventually death, in infected mammals. With few exceptions, including Australia, terrestrial rabies can be found worldwide. More than 55,000 deaths from rabies infection are reported annually; these are mainly in Asia and Africa where the primary reservoir is the domestic dog.
Despite ongoing control efforts in Indonesia, canine rabies remains a disease of critical concern there. Although rabies is not endemic in Australia, at less than 300km away in Indonesia, a rabies incursion is a likely and imminent threat.
To improve preparedness for a canine rabies outbreak in Australia, I collected data on a number of extant dog populations in northern and eastern Australia. I used a range of methods including self-administered questionnaires, GPS telemetry collars, camera trapping and mark-recapture studies. Using my own data and parameters collected from the wider literature, I developed state-transition models to determine how rabies could spread through these dog populations. Finally, I used these same models to evaluate a range of control strategies, including dog removal and vaccination, to identify the most effective options for reducing impacts in Australian communities following a rabies incursion.
Model outputs suggested that rabies will progress differently within functionally different dog populations present within Australia. Restrained domestic dogs posed limited risk for rabies transmission, because interactions with other dogs were limited and generally supervised by owners. Free-roaming domestic and hunting dogs will likely play an important role in rabies transmission in some situations only, primarily based on their ability to roam, access to other free-roaming dogs and their interactions within and between dog groups. Wild dogs (including dingoes) proved the most critical type of dog for rabies spread and maintenance in Australia, because they are widely distributed, often in high abundance, roam over large distances and frequently interact.
I found that time to detection for rabies in wild dogs will likely be lengthy, probably due to low infection rates prior to an epidemic and limited contact with humans, relative to the other categories of dog that I studied. Further, the capacity of authorities to implement effective control strategies for wild dogs will likely be restricted because of limited access to individual animals. The economic costs of controlling a rabies outbreak involving wild dogs will be substantial and likely equivalent to the costs for extensive aerially-based wild dog control that are currently used in some areas of Australia (~Aus$34 km-2).
Australia’s current plans to address rabies incursions, which were developed in the 1990s are clearly outdated. My findings reveal that revision of these plans, taking specific account of relevant differences between restrained domestic dogs, free-roaming domestic dogs and extensive wild dog populations is necessary to ensure that Australia is adequately prepared for the arrival of canine rabies.
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Thesis DoctoralPublication A system dynamics approach to chain/network analysis in the primary industry sector: Case studies of beef, dairy, and amaranth in the developing world(2017) ;Dizyee, Kanar Hassan Hamza; ;Rich, Karl M; The research problem and gap this thesis examines is that although received value chain analysis (VCA) is well designed for establishing a narrative, describing the chain, and identifying influencing factors, it is less good at measurement and objective analysis. Similarly, analytical attempts to quantify value chains to date have mostly targeted micro - firm level - economic analysis and, hence, have been weak in analyzing and evaluating overall chain performance under a variety of policy and commercial interventions. A major gap in VCA is thus in understanding the impact of VC investments such as the general performance of a chain and the ability to evaluate ex-ante different options. The gaps in the widely used approaches to VCA include the lack of an approach to reconcile the various systems and constraints at different nodes or stages of the value chain. This thesis aims to address this gap by designing a conceptual framework to demonstrate the suitability of the system dynamics (SD) modelling approach to address the complexity of the agricultural value chains in a quantitative whole chain context. This thesis uses a SD modelling approach to build on value chain and partial equilibrium analysis to construct a conceptual framework to address the research gap identified in this thesis. The author then provide applications of the conceptual framework and SD models to three agricultural value chain case studies to provide a proof-of-concept and to direct future applications. The case studies represent different commodities (cattle, beef, milk, and crops) and regions (Botswana, Tanzania’s Kilosa district, and East Africa) across multiple chain stages, and in the contexts of market power, international trade, transboundary disease control, communal resources, food security, technology uptake, market reorganization, and development in an agricultural value chain context. The first case study on the beef value chain in Botswana reported an ex-ante impact assessment of policy changes associated with trade liberalization and disease management in a value chain context. It provided performance measures to evaluate the gains and losses of value chain actors (and of the whole chain) under various policy interventions. Model results suggested that although disease control policies benefit all value chain actors, gains from market liberalization come at the expense of substantial losses to Botswana Meat Commission (BMC) and its contracted feedlots. They also suggest that combining market liberalization policy reforms with better animal disease controls greatly improved the financial performance of all value chain actors. The second case study on the dairy value chain in Tanzania’s Kilosa district reported results of an ex-ante impact assessment to address issues of low productivity of local breed cows and limited market access. Interventions included provision of artificial insemination (AI) as a technological change to increase dairy productivity; and organizational change entailing a dairy market hub to enhance producer access to distant markets. The dairy case study evaluates the economic feasibility of switching from extensive pre-commercial production systems to more intensive more commercial production systems as means of upgrading the dairy value chain in Tanzania’s Kilosa district. The results demonstrated through multiple performance indicators – producer profits, milk production, proportion of cross-breed cattle in the total cattle population, and the volume of milk traded to market hubs and processors – shows the potential for upgrading the smallholder dairy value chain in Kilosa, but this requires that third parties support producers in the initial stages (first five years) of investment to subsidize the high costs of AI. The last case study on the amaranth value chain in East Africa examines the food security and commercialization potential of amaranth from a whole of chain perspective. It reported results of ex-ante impact assessment of the impact of producer adoption of improved production technologies (improved seed varieties) and changes in demand for amaranth products, on producer profits and planting behavior. It provided performance measures based on producer profits and endogenous land allocation to amaranth. This case study results showed that profitably upgrading and commercializing amaranth value chains requires multi-faceted and chain level interventions that improve supply and demand side conditions. Interventions that only target the supply side serve to increase amaranth production but have minor economic gains for producers. These case studies, through addressing different research questions and providing different value chain performance measures, served to show proof-of-concept and versatility of the conceptual framework. This demonstration emphasis has constrained the extent to which a comparison between SD and alternative modelling approaches is made. Such a comparison in the context of agricultural economics is deferred to other research. The modelling of case studies has similarly focused on demonstration of elements of the conceptual framework, at the expense of detailed coverage of industrial and sector characteristics.2452 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralUnderstanding factors affecting the synthesis of protoporphyrin IX in the shell gland of laying hens(2017-10-09) ;Khan, Samiullah; ; ; Nine experiments were performed to investigate how the synthesis and/or deposition of protoporphyrin IX (PP IX) into eggshell is influenced in brown-egg laying hens. The findings obtained in the first experiment (Chapter 2) showed that flock age and production system affected overall eggshell and egg quality. Egg weight was significantly higher in cage eggs, while albumen height was significantly higher in barn eggs. The mammillary layer ultrastructural variables showed no clear relationship with production system and flock age. Cuticle cover (ΔE*ab) was significantly higher in barn eggs compared with free range and cage eggs and was significantly higher in eggs from the 44 week old flock than for 64 and 73 week old flocks. In 1 gram of eggshell with and without cuticle, there was more PP IX in cage eggs followed by free range and barn eggs. The findings in experiment 2 (Chapter 3) indicate that eggs laid earlier in the day had deeper brown eggshell colour compared with the eggs laid later in the day. Egg position in a clutch had a clearer effect on eggshell quality in long clutches, as compared with medium and short clutches. The findings of the third experiment (Chapter 4) showed that different infectious bronchitis virus (IBV) strains affected the level of PP IX in eggshell differently. In unvaccinated laying hens, the mean PP IX per gram of shell was significantly higher on day 1 post-infection (p.i.) compared to day 7, after which PP IX increased with day p.i. In unvaccinated and vaccinated laying hens, PP IX decreased with increased day p.i. until day 12. The effect on loss of shell colour was more marked in the T strain infected group followed by N1/88, Vic S and A3 strains. Experiment four (Chapter 5) investigated reference gene stability in the shell gland in relation to time-points (time post-oviposition) of eggshell formation and nicarbazin treatment. The two most stable reference genes selected, HPRT1 and HMBS, were used for the normalisation of gene expression data obtained in experiment five (Chapter 6). The findings in experiment five showed that mitochondria per cell did not vary significantly with different time-points of eggshell formation and nicarbazin treatment. Genes involved in the synthesis of PP IX were regulated differentially in relation to time-points of eggshell formation. Feeding nicarbazin caused down-regulation of the ALAS1 gene that resulted in lower production of PP IX appearing in the shell gland tissue and eggshell. Experiment six (Chapter 7) investigated reference gene stability in the shell gland and spleen of infectious bronchitis virus (IBV) infected hens. The two most stable reference genes selected, TBP and YWHAZ, were used for the normalisation of gene expression data obtained in experiments seven and eight (Chapters 8 and 9). The RNA-sequencing findings in experiment seven showed that there were no differentially expressed genes (DEGs) involved in the mucosal immune system and eggshell formation in the shell gland between IBV challenged and control laying hens. However, there were 1608 and 1806 DEGs at 5 and 15 hrs time-points of eggshell formation, respectively. The Gene Ontology (GO) terms and functional gene analysis showed that the DEGs at 5 hr post-oviposition were mainly involved in ion transport and synthetic activities, while the DEGs at 15 hr were involved in energy metabolism and secretory activities, reflecting the peak stage of eggshell formation. The findings in experiment eight (Chapter 9) showed that IBV T infection significantly lowered mitochondrial count per cell in the shell gland region of the oviduct but not in the magnum or isthmus. The expression levels of nuclear DNA encoded genes involved in mitochondrial biogenesis and fission showed no clear correlation with mitochondrial count and were not significantly different between the control and challenged samples. The expression levels of all the genes except for PGC-1α were significantly affected by the time-points of eggshell formation. Experiment nine (Chapter 10) attempted to localize ALAS1, ALAD and FECH enzymes in shell gland tissue collected at different time-points (time post-oviposition) and in response to nicarbazin treatment. The findings showed that these antibodies did not recognise their respective proteins, possibly due to their amino acid sequences being derived from humans. PP IX fluorescence was not detected in Zenker Formol fixed tissue sections, stained or unstained, taken at different time-points and with or without nicarbazin treatment. Future work is suggested using chicken specific antibodies to localise cells involved in PP IX synthesis. Taken together, the findings in the current study broaden the understanding of factors affecting the synthesis and deposition of PP IX into eggshells.3647 714 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralUse of shelter by Merino sheep(2012) ;Taylor, Donnalee Bernice; ; The objectives of the studies conducted in this thesis were to improve knowledge of pregnant and lambing Merino ewes sheltering behaviour and to investigate an alternative means of moving sheep flocks within paddocks or to protected areas. Animal collar tracking devices with global positioning system (GPS) capabilities enabled continuous, unobtrusive tracking of sheltering behaviour throughout two lambing seasons in two nearby paddocks. Behavioural measures such as shelter-seeking was observed throughout the two experimental years and in both paddocks. The ewes consistently used shelter more than expected and more than the remainder of the paddock which was devoid of shelter. Extensive use of the leeward and windward side of shelter during high sheep chill days, suggests there may be wellbeing issues associated with inadequate provision of shelter for sheep throughout the year. Night camping in this study did not occur at the highest altitude, but rather at a high altitude where shelter was located. Bayesian change-point (bcp) analysis successfully identified change-points (reduced velocity) that could be associated with lambing in the majority of the closely monitored ewes. Based on this analysis the time period of morning grazing appeared to be the best in which to identify lambing. The feasibility of training Merino sheep and using these trained sheep to move flocks of naive sheep was also investigated. The sheep learned to approach the visual, auditory and visual+auditory stimuli and T-maze tests indicating that the sheep retained memory of the cues for over 130 days without reinforcement. The sheep were able to transfer the learned task from a familiar location to a novel one. Individual temperament of these animals was not related to their learning. This study demonstrated that sheep trained to respond to a stimulus do provide leadership when mixed with naive sheep flocks causing a flock to rapidly change position to congregate around an activated stimulus. These findings suggest that trained animals could be used to manipulate animal movement for farm management purposes such as movement to shelter.2239 971 - Some of the metrics are blocked by yourconsent settings
Publication Open AccessThesis DoctoralVocal behaviour as an indicator of lamb vigour(2016); ;Small, Alison; The viability and survival of the neonate lamb relies on its ability to communicate and maintain a strong attachment with its dam. To date there has been little concise information available about the role of the lamb's behaviour, and in particular the importance of acoustic cues, in this relationship as greater attention has been focused on maternal attributes important in facilitating the maternal-young bond. In human and rodent neonates, acoustic features of the distress vocalisation are used as indices of neurological deficit and integrity both at birth and in infant acoustic cry analysis. The aim of this thesis was to investigate potential behavioural indicators of lamb vigour, with a particular focus on vocal behaviour, within the first 12 hours of life. Such measures could provide valuable information for development of reproductive breeding objectives, and provide clarity regarding the role of the lamb in failed maternal-young interactions. Delayed vocalisation initiation in response to a separation stimulus was found to be associated with poor vigour-related behaviour reflecting the capacity of the lamb to reunite and follow the dam over 12 hours postpartum. Vocalisation delay was also associated with risk factors related to poor lamb survival including longer parturition duration, male sex, first parity, heavier birth weight and sire-related conformational attributes likely to result in a more difficult birth. Blood assay markers reflecting fetal distress including poor blood oxygenation, and elevated plasma glucose and lactate levels sampled at birth were also demonstrated to be correlated with vocalisation latency. These associations were concluded to reflect impacts on the lamb's neurological system rather than genetic influences because of evidence provided by within-litter comparisons, and to demonstrate neuroregenerative processes over a 12 hour measurement period. An analysis of lamb distress signals modelled on acoustic cry analysis of the human neonate was also undertaken to compare vocalisation characteristics of lambs with delayed responses to those with rapid responses indicating vigour. Signal features of delayed response lambs were more likely to demonstrate acoustic parameters reflecting glottal instability, lower amplitude and reduced repetition rate. These lambs were more likely to emit inefficient or inappropriate signals in the context of isolation. A significantly higher fundamental frequency, an indicator of pathology in the human infant, was not clearly demonstrated to be associated with compromised lambs in this study. It was also found in a two-choice test, where sheep dams were required to demonstrate a preference for signals of their own co-twins, that ewes preferred acoustic signals of lambs correlated with rapid vocalisation response, higher pitch and greater signal stability. The results indicate that delayed vocalisation responsiveness and other acoustic measures are associated with fetal compromise in the neonate lamb, as shown in the human and rodent models. It was concluded that delayed vocal initiation is a marker for poor postnatal outcome characterised by diminished responsiveness to a distress condition. This research has important implications for understanding failed maternal-young relationships and the consequences for survival in mammalian neonates.3603 941