Influence of Dietary Supplements on Growth of Beef Calves on Semi-Desert Range

Abstract

The growth of 160 weanling calves on semi-desert range during a period of 4 years was studied. Dietary supplements of phosphorus, energy (barley), protein (cottonseed meal, soybean meal and alfalfa) were fed to part of the animals in a 2 × 4 factorial-designed experiment. All cattle grazed the same range but were individually fed supplements in portable pens as they came in for water. During the winter all supplements except phosphorus increased the rate of gain above the control animals. Cattle fed protein supplements grew significantly faster than those fed the barley supplement. The rate of gain was equal for the protein-supplemented groups. During the summer, only phosphorus increased the rate of gain but for the entire year both phosphorus and winter protein supplements resulted in greater gains. Large yearly variatons in growth response were observed. Blood analyses were made periodically. The level of circulatory erythrocytes was greater when protein supplements were fed. Phosphorus supplements consistently increased the level of plasma phosphorus. Alfalfa, as a carotene source, had no effect on the level of plasma carotene or vitamin A. Cattle supplemented with barley had the highest level of plasma carotene; those supplemented with protein were least.