Use of nitrate and 'Propionibacterium acidipropionici' to reduce methane emissions and increase wool growth of Merino sheep

Title
Use of nitrate and 'Propionibacterium acidipropionici' to reduce methane emissions and increase wool growth of Merino sheep
Publication Date
2014
Author(s)
de Raphelis-Soissan, Victoire
Li, Li
Godwin, Ian
Barnett, Mark
( author )
OrcID: https://orcid.org/0000-0001-6306-7884
Email: mbarnet3@une.edu.au
UNE Id une-id:mbarnet3
Perdok, H B
Hegarty, Roger
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
CSIRO Publishing
Place of publication
Australia
DOI
10.1071/AN14329
UNE publication id
une:17894
Abstract
The effects of dietary nitrate and of Propionibacterium acidipropionici (PA) on methane and nitrous oxide emissions, methaemoglobinaemia, volatile fatty acid (VFA) concentration and productivity of sheep were studied. It was hypothesised that PA supplementation would increase the rate of nitrite reduction to ammonia in the rumen and therefore reduce risks of methaemoglobinaemia. Fine-wool Merino wethers (n ≤ 28; 31.8 ± 3.7 kg; 11 months of age) were acclimated to four isonitrogenous and isoenergetic diets based on oaten chaff (1.0 kg/day) supplemented with either urea (1.1% of DM; T1 and T2) or a nitrate source (2.0% of DM; T3 and T4) while T2 and T4 were also supplemented with PA (11.5 × 1010 CFU/day). Replacing urea with nitrate lowered methane production (g/day) by 19% and methane yield (g/kg DMI) by 15%, improved clean wool growth by 12% (P < 0.001) and tended to increase skin temperature (P < 0.1). Nitrate increased ruminal acetate to propionate ratio by 27%, increased plasma nitrite and nitrate concentrations and blood methaemoglobin (MetHb) level up to 45% of total haemoglobin. Nitrous oxide emission from sheep confined in respiration chambers was higher (P < 0.001) when nitrate was fed, lowering the net benefit of methane mitigation on global warming potential (CO2 equivalents/kg DMI) by 18%. In contrast, PA had little effect, decreasing total VFA concentration (P < 0.05), increasing rumen pH (P < 0.05) and clean wool growth (P < 0.05) of urea-fed sheep. This study confirmed the beneficial effects of nitrate on net greenhouse gas reduction and wool growth, but showed that methaemoglobinaemia risks may be higher when diets are fed at a restricted level and contain only low levels of readily fermented carbohydrate. PA supplementation was not effective in reducing methaemoglobinaemia, but did increase clean wool growth of urea-fed sheep.
Link
Citation
Animal Production Science, 54(10), p. 1860-1866
ISSN
1836-5787
1836-0939
Start page
1860
End page
1866

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