Performance and Milk and Blood Lipids of Milk Fat-Depressed Cows Fed Tallow and Sucroglyceride

Abstract

A double reversal trial with 12 Holstein cows evaluated the addition of 6% tallow and 5.5% tallow plus .5% sucroglyceride (a nonionic surface active agent) to the concentrates supplementing alfalfa hay (1.25% of the body weight fed daily) to provide net energy at 110% of Morrison's standard. The trial period included natural summer environmental conditions encountered in Central Arizona which produced thermal stress on the cows during the first two periods.Added dietary fats showed no effect on measures of digestibility of feed dry matter, protein, and acid-detergent fiber although ether extract was 15% more digestible. Dietary additions showed no effect on urine pH, rumen pH, and volatile fatty acid amounts or ratios; milk and milk fat yields, fatty acid profile in the blood serum fractions (total lipids, cholesterol esters, triglycerides, free fatty acids, diglycerides, monoglycerides and phospholipids), or in milk fat.There were no significant effects for sucroglyceride fed at this level.Period effect would suggest that a mean daily temperature of 32.9C produced an increase in relative proportions of short chain (C10–C15) fatty acids of the triglyceride and free acid fractions of blood serum lipids.