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.

TW, Knight, CA Morris, RW Purchas, and M Agnew

Proceedings of the New Zealand Society of Animal Production, Volume 63, Queenstown, 21-24, 2003