Conjugated linoleic and trans-vaccenic acids in grass-fed
beef and lamb
T.W. KNIGHT, C.A. MORRIS, R.W. PURCHAS AND M. AGNEW
AgResearch Grasslands, PB 11008, Palmerston North, New Zealand.
NZSAP 2003 Abstract No. 7
Proceedings of the New Zealand Society of Animal Production
63: 21-24
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.
Keywords: NZSAPAB;
conjugated linoleic acid; trans-vaccenic acid; beef; lamb
Last Updated 8/07/2004
