THE INFLUENCE OF THE AMOUNT OF PROTEIN AND ENERGY IN THE RATION OF REPLACEMENT EWE LAMBS ON BODY WEIGHT GAINS AND WOOL PRODUCTION

Abstract

Three experiments were carried out with replacement ewe lambs to determine the influence of feeding rations containing three levels of protein, each at two levels of digestible energy. The three levels of protein were approximately 8, 9.5, and 11 per cent in the first two experiments, and 6, 9, and 12 per cent in the third experiment.Increasing the amount of protein in the ration resulted in an increase (p <.05) in the apparent digestibility of the protein, but no change in the percentage of protein retained or in the digestibility of the dry matter and gross energy. Increasing the digestible energy content of the ration by substituting corn starch for wheat straw or oat hulls reduced (p <.05) the digestibility and retention of protein in Experiments 2 and 3, but had no effect in Experiment 1.Body weight gains and wool growth of lambs fed rations containing wheat straw or oat hulls did not increase to so great an extent as those fed corn starch. This would indicate that energy was a limiting factor for maximum production in the lower digestible energy rations. In general, weight gains and wool production increased (p <.05) when the daily intake of D.C.P. was increased from approximately 0.10 to 0.13 pounds. Increasing the D.C.P. from 0.13 to 0.16 pounds (0.19 in Experiment 3) caused no further increase in body gains but increased (p <.05) wool production.On the basis of these results, the average D.C.P. requirements of a ewe lamb weighing 85 pounds and consuming 1.3 pounds T.D.N. was 0.13 pounds (0.16 pounds when wool production was considered).