Conjugated linoleic acid content of milk from cows fed different diets

Conjugated linoleic acid in milk was determined from cows fed different die ts. In Experiment 1, cows were fed either normal or high oil corn and corn silage. Conjugated linoleic acid was 3.8 and 3.9 mg/g of milk fatty acids i n normal and high oil treatments, respectively. In Experiment 2, cows consu med one-third, two-thirds, or their entire feed from a permanent pasture. A lfalfa hay and concentrates supplied the balance of feed for the one-third and two-third pasture treatments. Conjugated linoleic acid was 8.9, 14.3, a nd 22.1 mg/g of milk fatty acids in the one-third, two-third, and all pastu re treatments, respectively. Cows grazing pasture and receiving no suppleme ntal feed had 500% more conjugated linoleic acid in milk fat than cows fed typical dairy diets (Experiment 1). In Experiment 3, cows were fed either a control diet containing 55% alfalfa silage and 45% grain, or similar diets supplemented with 3% fish meal, or 250 g of monensin/cow/per day, or fish meal and monensin together. Conjugated linoleic acid was 5.3, 8.6, 6.8, and 8.9 mg/g of milk fatty acids in the control, fish meal, monensin, and fish meal plus monensin treatments, respectively. In Experiment 4, cows were fe d either finely chopped alfalfa hay (Treatment 1), or coarsely chopped alfa lfa hay (Treatment 2) in a 50% forage and 50% grain diet, or 66.6% grass ha y and 33.4% grain (Treatment 3), or 98.2% grass hay (Treatment 4). Conjugat ed linoleic acid was 7.3, 8.3, 9.0, and 7.9 mg/g of milk fatty acids in tre atments 1 through 4, respectively.