The Nutritive Value of Cottonseed Meal, Soybean Meal, and Peanut Meal When Used Separately and Together to Supplement the Protein of Prairie Hay in Experiments with Steers'

The use of high-protein feeds by hvestock feeders to supplement the protein of many common roughages for beef cattle is a general practice based on sound nutrition principles. Protein supplements, as a rule, effect a marked increase in the feed intake of animals on fibrous rations. By providing a better nutrient balance in a ration they increase the efficiency of utilization of the major feed nutrients. Maximum use can be made of available roughage when fed in this manner. For a long time, cottonseed meal has been a standard protein supplement for cattle on the range and in the feed lot. In recent years soybean meal of equal protein content has been used in various forms. More recently, peanut meal has become available in some localities in sufficient quantity to attract the attention of cattlemen. Question has naturally arisen as to the relative protein value of these supplements when used alone and as a mixture to supplement low-protein rations. Knowledge of the nutritive value, for cattle, of the protein in these meals is limited largely to the results of feed-lot tests so conducted as to measure the over-all nutritive effects of the added supplément. Although of practical value, these trials are frequently not sufficiently well controlled to bring out possible differences in protein quality. By means of nitrogen balance studies, however, quantitative measurement can be made of the utilization of protein from different sources, and the efficiency of the utilization can be determined in both digestion and metabolism. The utilization by ruminants of the protein in soybean meal has been studied in this manner by Harris, Work, and Henke (5),^ Swanson and Herman (13)^ and Miller and Morrison (7). The general methods of investigation with permissible modifications have been discussed by Mitchell (10) in a recent review. The primary purpose of the investigation reported here was to determine whether or not the protein furnished by a combination of cottonseed meal, soybean meal, and peanut meal is of higher nutritive value for the maintenance and growth of cattle than an equivalent amount of protein furnished by any one of these three supplements.