Soybean Meal, Urea and Extruded Starch-Urea Products Compared as Protein Supplements in High-Roughage Lamb Rations2

Abstract

Using growth, nitrogen retention, and rumen ammonia and volatile fatty acid concentrations as response criteria, extruded starch-urea products (44% protein equivalent) were compared with soybean meal (SBM) as nitrogen supplements in high-roughage lamb rations. Though feed consumption was similar for groups fed an extruded sorghum grain-urea product and SBM, gain per unit feed was slightly, but not significantly, higher for those fed SBM. In a nitrogen balance and digestion study, sorghum grain and potatoes, each at two gelatinization levels, were used as base starches for extruded products. Dry matter and energy digestibilities were lower (P<.05) for the ration supplemented with low-cooked (partially gelatinized) potatoes than for any of the others. Nitrogen retention was lower (P<.05) in the low-cook potato group; other treatments were similar. Gelatinization improved utilization of potato starch more than sorghum starch. Lambs fed the low-cook potato product had higher (P < .05), and those fed SBM lower (P < 05), rumen ammonia concentrations than other groups. No relation was found between volatile fatty acid (VFA) concentrations and nitrogen source. Copyright © 1974. American Society of Animal Science. Copyright 1974 by American Society of Animal Science.