@article {3672,
	title = {Sheep divergently selected for methane yield showed differences in meat fatty acid composition},
	journal = {New Zealand Journal of Animal Science and Production},
	volume = {81},
	year = {2021},
	month = {01/2022},
	pages = {173-178},
	address = {Online},
	abstract = {The purpose of this work was to investigate whether 18-month-old rams from the methane selection lines differed in their levels of soft tissue depth over the 12th rib (GR, as a proxy of carcass fatness) intramuscular fat (IMF), and the fatty acid composition of IMF. The rumen is the site of microbial biohydrogenation of consumed plant fatty acids and synthesis of unique microbial body fatty acids. It is known that there are differences in the microbiome and fermentation characteristics of sheep selected for and against methane production (methane selection lines). When comparing the high and low lines several differences were found. Rams from low-methane-yield-selection lines tended to have lower GR (P<0.06) than those from high line rams, but there was no evidence for a difference in levels of IMF between the lines (P=0.77). There were, however, many significant differences in the fatty acid composition (as a \% of total fatty acids) of the IMF between the lines. The IMF from the low-methane-yield line had a significantly (P<0.05) higher proportion of branched-chain fatty acids, and fatty acids that are associated with the early stages of the biohydrogenation pathways in the rumen, specifically conjugated linoleic acid (CLA) and C18:1 t11 but with less C18:0 stearic acid (the end product of biohydrogenation) and a significantly higher proportion of C16:1 t9 which is produced through β-oxidation of C18:1 t11. These results provide insight into how differences in sheep from the methane-yield selection line may influence the fatty acid composition of their fat.


Keywords: Methane; sheep; intramuscular fat; fatty acid composition},
	issn = {1176-5283},
	author = {PL Johnson and Agnew M and Jonker A and Hickey SM and McEwan JC and Bryson B and Dodds KG and Rowe SJ}
}
@conference {41397,
	title = {Conjugated linoleic and trans-vaccenic acids in grass-fed beef and lamb},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {21-24},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {Cis-9 trans-11 conjugated linoleic acid (CLA) found in ruminant milk and meat has several human health benefits of which the anti-cancer effect is the most prominent. Trans-vaccenic acid (TVA) is a precursor of CLA and can be considered as another dietary source of CLA. This paper uses data from three published papers to compare the CLA and TVA concentrations in the longissimus lumborum muscle (LL) from cattle and lambs, to determine the within- group variation, and to identify factors influencing this variation. The paper discusses the contribution lean beef and lamb can make to the estimated human daily required intake (DRI) for CLA. The CLA and TVA content was measured in the LL from two groups of cattle (n = 15 and n = 100) and two groups of lambs (n = 30 and n = 12). CLA and TVA concentrations in the total fatty acids (TFA) was higher (P<0.001) in lamb than in beef. The coefficients of variation within each group of animals ranged from 23-41\% for CLA and 25-68\% for TVA, indicating a large variation in the concentration of these fatty acids among animals. A number of factors contributed to these differences but the largest difference was found in lambs, where there was a 41\% higher (P<0.01) CLA concentration in the TFA from lambs born to ewes with high CLA concentrations than from lambs born to ewes with low CLA concentrations in their milk fat. A 100g portion of lamb containing 2-4\% lipid could contribute 2-5\% of the estimated 750mg DRI of CLA for humans. However, if dietary TVA was assumed to be equivalent to CLA, then lamb could contribute 13-15\% of the DRI. We conclude that lamb can provide a significant proportion of the DRI for CLA for humans and there is scope for farmers to further increasing the CLA and TVA content of beef and lamb.},
	issn = {1176-5283},
	author = {Knight TW and Morris CA and Purchas RW and Agnew M}
}
