Effect of Soybean Meal, Raw Soybeans, Corn Gluten Feed, and Urea on the Concentration of Rumen Fluid Components at Intervals After Feeding

Trials utilizing three fistulated steers, in two Latin-square designed experiments, were conducted with five rations equal in digestible protein and containing cottonseed hulls, plus one of the following protein supplements : soybean meal, raw soybeans, corn gluten feed, urea, or area -b soybean nleal.In the first experiment, soybean meal, raw soybeans, and corn gluten feed were fed.The corn gluten feed ration was associated with the highest concentrations of total nitrogen (N) and protein N in the rumen fluid; the ration of raw soybeans was associated with the lowest concentrations; and the soybean meal ration with intermediate concentrations.Concentrations of ammonia-N were highest with soybean meM and the lowest with raw soybeans.Total volatile fatty acids (VFA) were similar for soybean meal and corn gluten feed.Soybean meal, urea, and urea -b soybean meal were fed in the second experiment.The soybean meal ration was associated with the highest concentrations of total N and protein N; the urea ration with the lowest concentrations; and the urea -b soybean meal ration with intermediate concentrations.Concentrations of ammonia-N were highest with urea and lowest with soybean meal.The urea ration was associated with a significantly lower (P < 0.01) total VFA concentration and more alkaline pI-I.During recent years much progress has been made in the study of N metabolism of ruminants and of the role of rumen microorganisms in protein digestion.Efforts have been made to determine the efficiency of various N sources in satisfying the N requirements of the ruminant.Soybean meal has been studied extensively