Effect of dietary conjugated linoleic acid (CLA) on milk composition of dairy cows

摘要

Influencing the milk fat content and the fatty acid pattern by diet composition and feed supplements has been an aim of animal nutritionists for a long time. Apart from diet variation and supplementation of unsaturated fatty acids (Flachowsky et al.,2006), some authors showed that dietary supplementation of conjugated linoleic acids (CLA) inhibits milk fat content and alters fatty acid composition (e.g. Kraft etal, 2000; Bauman and Griinari, 2003). Mainly the trans-10, cis-12 C_(18)-isomers are recognised to be responsible for the reduction of milk fat concentration (Lock et al., 2006). A decrease in milk fat yield could potentially reduce the energy demand in order to minimise the post partum negative energy balance of high-yielding dairy cows. Onthe grounds that CLA are claimed for health promoting effects in human, it is occasionally recommended to increase the CLA concentration of milk. However, the discussion about the effects of CLA on human nutrition remains controversial. The preliminarystudy was conducted to assess the effects of increasing amounts of dietary CLA on feed intake and milk composition of cows in early lactation.