Starea, Urea and Sulfur in Beef Cattle Rations

Abstract

Two experiments involving 104 steers were conducted to study the influence of nitrogen source and added sulfur in finishing rations comparing two levels of sulfur and soybean meal, urea, Starea and urea+alfalfa meal supplements in Experiment I and urea with Starea supplements in Experiment II. Results revealed that feedlot performance, carcass data and ruminal fluid constituents were unaffected by nitrogen source. Consumption of rations with added sulfur was lower in both studies and utilization of feed was more efficient by steers fed high sulfur rations in Experiment I. Feedlot gain, carcass gain and carcass weight were significantly decreased in steers fed high sulfur rations (Experiment II). Lower molar percentages of acetate and greater molar percentages of propionate and valerate were detected in rumen fluid from steers receiving supplemental sulfur in Experiment I. Acetate to propionate ratios were also significantly lower in cattle fed high sulfur rations. Similar treatments involving sources of supplemental nitrogen and the addition of sulfur as in Experiment I were imposed on 100 calves which were fed a growing ration based on corn silage. Calves supplemented with SBM had greater average daily gains than calves fed urea, urea+alfalfa meal or ground corn supplements. The response of calves fed Starea was intermediate between that of calves fed SBM and those fed other urea-containing supplements. The addition of elemental sulfur did not influence performance. Levels of ammonia were markedly higher in samples from a fistulated steer receiving urea than from one receiving SBM. An early rise followed by a rapid decline of ruminal ammonia was detected in rumen contents from the steer fed Starea. Copyright © 1972. American Society of Animal Science . Copyright 1972 by American Society of Animal Science