Comparison of Four Levels of Protein Supplementation with and without Oral Diethylstilbestrol on Daily Gain, Feed Conversion and Carcass Traits of Bulls

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Abstract
A factorial arrangement of treatments testing effects of two levels (0 and 10 mg daily) of oral diethylstilbestrol (DES) and four levels of protein supplementation (.23, .41, .59 and .77 kg 50% protein soybean meal daily) was utilized in each of 2 years. A total of 153 Angus bull calves was used in studying effects of protein supplementation and DES on daily gain, feed utilization and carcass traits. Feeding DES produced more rapid gains (1.37 vs 1.21 kg/day; P<.01) and more efficient dry matter conversion to gain (4.73 vs 5.39 kg/kg gain; P<.01) than controls only in the first 28 days of the feeding trial. The lowest level of protein supplementation produced gains that were 22% below the average of the three higher levels of supplementation (.93 vs 1.19 kg/day). Low protein resulted in carcasses with less fat thickness than animals fed higher protein levels. The minimum protein level for optimal growth of young bulls below 400 kg body weight was greater than 10%. Higher levels (up to 14%) resulted in improved gain during the first 56 days on feed at weights below 250 kg.) There were no significant interactions between DES and protein supplementation. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.