Effects of nutrition on the conjugated linoleic acid content of milk
Thesis (MScAgric (Animal Sciences)--University of Stellenbosch, 2007.
The objective of this investigation was to determine the effect of supplemented conjugated linoleic acid (CLA) on milk production and milk composition of lactating dairy cows in production systems commonly used in South Africa. In the first of three trials, samples of 24 bulk tanks were collected to get an impression of the CLA status of milk in the Western Cape Province, South Africa. Six samples were each collected from Jersey and Holstein herds in total mixed ration (TMR)-based systems. Another six samples were each collected from Jersey and Holstein herds on pasture-based systems. An additional three samples were also collected from co-op silos. One of these came from a mixed herd on TMR, one from a Jersey herd on TMR and the third sample from a mixed herd on pasture. The CLA levels of the milk were within the range reported in literature, albeit on the low side. The mean CLA level in milk fat of cows from pasture and TMR-based systems were 10.5 and 5.45 mg/g of fatty acids, respectively. This is in agreement with trends reported in the literature with cows on pasture having higher levels of CLA in their milk than cows on TMR’s. In this study, breed had no effect on the CLA level in milk fat.