Effects of a commercial feed containing conjugated linoleic acid on the production of milkcomponents and the value of milk

摘要

This study was to evaluate changes in cow productivity and milk value from feeding a rumen-protected form of CLA to pasture-fed dairy cows in early lactation. 30 New Zealand Friesian dairy cows were randomly assigned at calving to either Og (control)or 120g/d of a commercial rumen protected feed containing CLA from 4 days post-calving for 16 weeks. Milk yield and composition data was collected weekly. A simulation model was used to calculate yield of dairy products based on accumulated yields of milk and its components per cow during the experimental period. Feeding CLA reduced (P<0.001) fat concentration (3.1% vs 4.2%) and increased (P<0.05) milk yield (2688 kg vs 2423 kg), and protein yield (89.9 kg vs 81.2 kg). The effect of CLA on milk fat concentration was reflected in the yield of dairy products and milk value. Milk from cows fed CLA had less (P<0.01) excess of fat sold as butter (48.4 vs 69.4 kg butter). The value of milk (dollar/kg MS) was higher (P<0.001) from cows fed CLA than from control cows at 2002/03 prices (3.87 dollar vs 3.66 dollar) and when butter price was low (3.56 dollar vs 3.24 dollar).