Dietary nitrate metabolism and enteric methane mitigation in sheep consuming a protein-deficient diet

Title
Dietary nitrate metabolism and enteric methane mitigation in sheep consuming a protein-deficient diet
Publication Date
2020
Author(s)
Villar, L
Hegarty, Roger
Van Tol, M
Godwin, I
Nolan, J
( author )
OrcID: https://orcid.org/0000-0001-7949-950X
Email: jnolan@une.edu.au
UNE Id une-id:jnolan
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
CSIRO Publishing
Place of publication
Australia
DOI
10.1071/AN18632
UNE publication id
une:1959.11/53119
Abstract
It was hypothesised that the inclusion of nitrate (NO3) or cysteamine hydrochloride (CSH) in a protein deficient diet (4.8% crude protein; CP) would improve the productivity of sheep while reducing enteric methane (CH4) emissions. A complete randomised designed experiment was conducted with yearling Merino sheep (n = 24) consuming a protein deficient wheaten chaff control diet (CON) alone or supplemented with 1.8% nitrate (NO3; DM basis), 0.098% urea (Ur, DM basis) or 80 mg cysteamine hydrochloride/kg liveweight (CSH). Feed intake, CH4 emissions, volatile fatty acids (VFA), digesta kinetics and NO3, nitrite (NO2) and urea concentrations in plasma, saliva and urine samples were measured. There was no dietary effect on animal performance or digesta kinetics (P > 0.05), but adding NO3 to the CON diet reduced methane yield (MY) by 26% (P = 0.01). Nitrate supplementation increased blood MetHb, plasma NO3 and NO2 concentrations (P < 0.05), but there was no indication of NO2 toxicity. Overall, salivary NO3 concentration was greater than plasma NO3 (P < 0.05), indicating that NO3 was concentrated into saliva. Our results confirm the role of NO3 as an effective additive to reduce CH4 emissions, even in a highly protein-deficient diet and as a source of additional nitrogen (N) for microbial protein synthesis via N-recycling into saliva and the gut. The role of CSH as an additive in low quality diets for improving animal performance and reducing CH4 emissions is still unclear.
Link
Citation
Animal Production Science, v.60 (2)
ISSN
1836-5787
1836-0939

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