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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #105629
Title: CONJUGATED LINOLEIC ACID CONTENT OF MILK FROM COWS FED DIFFERENT DIETS

Author
item DHIMAN, T - UTAH STATE UNIV LOGAN
item ANAND, G - UNIV OF WISCONSIN MADISON
item Satter, Larry
item PARIZA, M - UNIV OF WISCONSIN MADISON

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/17/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Conjugated linoleic acid (CLA), produced by bacteria in the forestomach of ruminants, is present in the fat portion of foods derived from ruminant meat and milk. Milk products and beef are therefore the principal sources of CLA in the American diet. Experiments with laboratory animals have shown that CLA can prevent formation of some types of cancer, and can have significant effect on body composition, causing more lean and less body fa in several animal species. It is of interest, therefore, to know if the CLA content of cows milk can be increased, and therefore possibly enhance the value of milk products for human consumption. Four experiments were conducted to evaluate diet modifications and their effect on CLA content of milk. Of the diet combinations tested in this experiment, the only treatment having significant effect was that pasture fed cows had up to five times as much CLA in their milk as confinement (conventionally) fed cows. This study shows that dietary manipulation of the cow's diet can increase CLA content of milk, and possibly enhance the value of milk products as healthy food items in human diets. This research will help dairy producers and milk processors produce a more desirable product for consumers. Consumers will be the ultimate beneficiaries if CLA proves helpful in the human diet.

Technical Abstract: Conjugated linoleic acid was determined in milk from cows fed different diets. 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 in normal and high oil treatments, respectively. In Experiment 2, cows consumed one-third, two-thirds or their entire feed from a permanent pasture. Alfalfa hay and concentrates supplied the balance of feed for the one-third and two-thirds pasture treatments. Conjugated linoleic acid was 8.9, 14.3, and 22.1 mg/g of milk fatty acids in the one-third, two-thirds and all pasture treatments, respectively. Cows grazing pasture and receiving no supplemental 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/d, 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 fed either finely chopped alfalfa hay (Treatment 1), or coarsely chopped alfalfa hay (Treatment 2) in a 50% forage and 50% grain diet, or 66.6% grass hay and 3.4% grain (Treatment 3), or 98.2% grass hay (Treatment 4). Conjugated linoleic acid was 7.3, 8.3, 9.0, and 7.9 mg/g of milk fatty acids in treatments 1 through 4, respectively.