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Title: An initial investigation on rumen fermentation pattern and methane emission of sheep offered diets containing urea or nitrate as the nitrogen source
Contributor(s): Li, Li (author); Davis, Jennifer (author); Nolan, John V  (author)orcid ; Hegarty, Roger  (author)
Publication Date: 2012
DOI: 10.1071/AN11254
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Abstract: The effects of dietary nitrate and of urea on rumen fermentation pattern and enteric methane production were investigated using 4-month-old ewe lambs. Ten lambs were allocated into two groups (n = 5) and each group was offered one of two isonitrogenous and isoenergetic diets containing either 1.5% urea (T1) or 3% calcium nitrate (T2). Methane production was estimated using open-circuit respiration chambers after 6 weeks of feeding. No difference in nitrogen (N) balance, apparent digestibility of N or microbial N outflow existed between treatments (P> 0.05). Animals offered the T2 diet lost less energy through methane than did those fed the T1 diet (P < 0.05). Total volatile fatty acid concentration, molar proportion of propionate, and the molar ratio of acetate to propionate in rumen fluid were not affected by dietary N source. Compared with urea inclusion, nitrate inclusion caused a significantly higher acetate and lower butyrate percentage in rumen volatile fatty acid. Nitrate supplementation tended to lower methane production by ~7.7 L/day relative to urea supplementation (P = 0.06). Methane yield (L/kg DM intake) was reduced (P < 0.05) by 35.4% when 1.5% urea was replaced by 3% calcium nitrate in the diet. Emission intensity (L methane/kg liveweight gain) was ~17.3% lower in the nitrate-supplemented sheep when compared with urea-fed sheep; however, the reduction was not statistically significant (P > 0.05). This study confirms that the presence of nitrate in the diet inhibits enteric methane production. As no clinical symptoms of nitrite toxicity were observed and sheep receiving nitrate-supplemented diet had similar growth to those consuming urea-supplemented diet, it is concluded that 3% calcium nitrate can replace 1.5% urea as a means of meeting ruminal N requirements and of reducing enteric methane emissions from sheep, provided animals are acclimated to nitrate gradually.
Publication Type: Journal Article
Source of Publication: Animal Production Science, 52(6 & 7), p. 653-658
Publisher: CSIRO Publishing
Place of Publication: Melbourne, Australia
ISSN: 1836-5787
Field of Research (FoR) 2008: 070204 Animal Nutrition
Field of Research (FoR) 2020: 300303 Animal nutrition
Socio-Economic Objective (SEO) 2008: 839802 Management of Greenhouse Gas Emissions from Animal Production
Socio-Economic Objective (SEO) 2020: 190302 Management of greenhouse gas emissions from animal production
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
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