Effect of Dietary Protein and Sunflower Meal on Blood Serum Cholesterol of Dairy Heifers

Abstract

Effects of dietary protein and protein supplement on cholesterol in blood serum of Holstein heifers were determined in two replications of a 2 × 2 factorial study involving 16 animals. Treatment variables were two crude proteins, either low (12%) or high (20%), and two protein supplements with soybean meal or sunflower meal. Rations contained 21% acid-detergent fiber supplied by sunflower hulls. Free serum cholesterol (17.9 mg/100 ml) from heifers consuming the high protein rations was lower than that of animals on low protein (28.2 mg/100 ml). The same degree and direction of interaction between quantities of protein and sources of protein were exhibited by total and esterified cholesterols. Concentrations of total cholesterol were not different among treatment groups, but quadratic responses with weeks of trial were significant. The lowest free cholesterol (16.4 mg/100 ml) was recorded by heifers on sunflower meal on the high protein ration. Composition of serum proteins was not altered by sources or amounts of protein in the ration. Weight gains and growth efficiency (gain/feed) were higher in animals on high protein, irrespective of the protein supplement. © 1980, American Dairy Science Association. All rights reserved.