Trans-10, cis-12 conjugated linoleic acid reduces milk fat synthesis in lactating goats

M. Rovai, A.L. Lock, T.A. Gipson, A.L. Goetsch, and D.E. Bauman

Journal of Animal Science 84(Supplement 1):294. 2006

The efficacy of trans-10, cis-12 conjugated linoleic acid (CLA) in reducing milk fat synthesis in dairy cows and sheep has been well documented. However, recent examinations of the effects of trans-10, cis-12 CLA on milk fat synthesis in lactating goats have proved inconclusive. The current study was therefore designed to determine if a lipid-encapsulated trans-10, cis-12 CLA supplement (LE-CLA; BASF AG, Ludwigshafen, Germany) would inhibit milk fat synthesis in lactating goats. Thirty multiparous Alpine dairy goats (50 ñ 7.4 kg) in late lactation were randomly assigned in a 3 x 3 Latin square experiment. Goats fed a 60% concentrate diet (20% bermuda grass hay and 20% alfalfa pellets) received either A) unsupplemented (Control), B) supplemented with 30 g/d LE-CLA (low-dose; LLE), or C) supplemented with 60 g/d LE-CLA (high-dose; HLE). The LE-CLA supplement supplied 3 and 6 g/d of trans-10, cis-12 CLA for the LLE and HLE treatments, respectively. Treatment periods were 14 d in length with a 14 d washout interval. Milk yield, DMI, and milk protein content and yield were unaffected by treatment (P > 0.05). Compared with Control, milk fat yield was reduced 8.1% by the LLE treatment and 21.2% by the HLE treatment (P < 0.001), with milk fat content reduced 4.4 and 16.0% by the LLE and HLE treatments, respectively (P < 0.001). In conclusion, the results of the present study demonstrate that trans-10, cis-12 CLA reduces milk fat synthesis in lactating goats in a manner similar to that observed in lactating dairy sheep and cows. However, dose-response comparisons suggest that the degree of reduction in milk fat synthesis is less in goats compared with other lactating ruminant species studied. Further studies are required to verify and extend these results and to elucidate the mechanism of action for the effects observed with trans-10, cis-12 CLA supplementation.