Effects of Whey Components and Methionine Analog on Bovine Milk Fat Production

Abstract

In three experiments, dietary whey products and methionine analog were evaluated for their effect on milk fat production, rumen fermentation, and lipid metabolism in the bovine. In Experiment I the effects of substituting either 10% partially delactosed whey, 10% hydrolyzed whey, 5% lactose, or 5% whey mineral-protein into a pelleted concentrate which supplied 86% of’ the total ration were compared in 20 lactating cows. In a second period of Experiment I variables were increased 1.5-fold in an unpelleted ration. Most effective recovery of milk fat was associated with the partially delactosed whey followed by whey mineral-protein feeding (P < .01). Milk fat increased in all groups when cows were changed to an unpelleted concentrate (P < .01). Experiment II in two parts compared the effects of partially delactosed whey and methionine analog with 24 lactating cows. A high concentrate ration was compared with the same concentrate containing 15% of the whey during treatment Period A. In Period B several cow groups of Period A were switched to a different treatment. Treatments were control, 15% partially delactosed whey and 40 g of methionine analog added per day. Milk fat percentage was enhanced (P < .05) by the whey in Period A and was associated with a relative increase in ruminal butyrate (P < .01). In the second phase, methionine analog resulted in more milk fat (P < .01) relative to appropriate controls. Ruminal butyrate was higher (P < .05) for both the whey and analog fed cows. Triglycerides were higher in the serum dextran sulfate precipitable lipoproteins of the control cows relative to the whey or analog fed cows. In experiment III, two replications of a 3 × 3 Latin square arrangement were utillized. All cows received 85% intake as concentrate. Treatments were control, 15% partially delactosed whey in concentrate and40 g per day of methionine analog. Partially delactosed whey and methionine analog increased the relative amounts of ruminal acetate (P < .05) and butyrate (P < .01) and decreased ruminal propionate (P < .01). Ruminal volatile fatty acid differences were not reflected in milk fat content. Arteriovenous differences indicate that the whey and the analog may enhance triglyceride transport into the mammary gland. © 1971, American Dairy Science Association. All rights reserved.