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Title: Feed deprivation in Merino and Terminal sired lambs: (1) the metabolic response under resting conditions
Contributor(s): Stewart, S M (author); McGilchrist, P  (author)orcid ; Gardner, G E (author); Pethick, D W (author)
Publication Date: 2019-07
DOI: 10.1017/S1751731118002975
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Abstract: The aim of this study was to examine the metabolic response to feed deprivation up to 48 h in low and high yielding lamb genotypes. It was hypothesised that Terminal sired lambs would have decreased plasma glucose and increased plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB) concentrations in response to feed deprivation compared to Merino sired lambs. In addition, it was hypothesised that the metabolic changes due to feed deprivation would also be greater in progeny of sires with breeding values for greater growth, muscling and leanness. Eighty nine lambs (45 ewes, 44 wethers) from Merino dams with Merino or Terminal sires with a range in Australian Sheep Breeding Values (ASBVs) for post-weaning weight (PWT), post-weaning eye muscle depth and post-weaning fat depth (PFAT) were used in this experiment. Blood samples were collected via jugular cannulas every 6 h from time 0 to 48 h of feed deprivation for the determination of plasma glucose, NEFA, BHOB and lactate concentration. From 12 to 48 h of feed deprivation plasma glucose concentration decreased (P<0.05) by 25% from 4.04 ± 0.032 mmol/l to 3.04 ± 0.032mmol/l. From 6 h NEFA concentration increased (P<0.05) from 0.15 ± 0.021mmol/l by almost 10-fold to 1.34 ± 0.021mmol/l at 48 h of feed deprivation. Feed deprivation also influenced BHOB concentrations and from 12 to 48 h it increased (P<0.05) from 0.15 ± 0.010mmol/l to 0.52 ± 0.010 mmol/l. Merino sired lambs had a 8% greater reduction in glucose and 29% and 10% higher NEFA and BHOB response, respectively, compared to Terminal sired lambs (P<0.05). In Merino sired lambs, increasing PWT was also associated with an increase in glucose and decline in NEFA and BHOB concentration (P<0.05). In Terminal sired lambs, increasing PFAT was associated with an increase in glucose and decline in NEFA concentration (P<0.05). Contrary to the hypothesis, Merino sired lambs showed the greatest metabolic response to fasting especially in regards to fat metabolism.
Publication Type: Journal Article
Source of Publication: Animal, 13(7), p. 1458-1467
Publisher: Cambridge University Press
Place of Publication: United Kingdom
ISSN: 1751-732X
Fields of Research (FoR) 2008: 070204 Animal Nutrition
Fields of Research (FoR) 2020: 300303 Animal nutrition
Socio-Economic Objective (SEO) 2008: 830310 Sheep - Meat
830311 Sheep - Wool
Socio-Economic Objective (SEO) 2020: 100412 Sheep for meat
100413 Sheep for wool
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Appears in Collections:Journal Article
School of Environmental and Rural Science

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