PSVI-6 Effects of Partial or Total Replacement of Soybean Meal with Urea on Feed Efficiency in Nellore × Red Angus Growing Bulls

Abstract

Abstract Soybean meal (SBM) is the primary protein source used worldwide for livestock. but is a high-cost protein source than other alternative protein sources such as urea. This study aimed to evaluate the effects of partial or total replacement of SBM with urea on dry matter intake (DMI), average daily gain (ADG) and feed efficiency of finishing Nellore × Red Angus crossbreed bulls. Nellore × Red Angus crossbred bulls (n = 30; average initial BW = 383.5 ± 8 kg; age = 9 ± 1 mo) were utilized in a completely randomized design for 93 days (9 d adaptation period + 84 d finishing period). Bulls were randomly assigned to receive 1 of 3 dietary treatments containing different replacement levels of soybean meal with urea (diet DM basis): 0% replacement (R-0%); 50% replacement (R-50%); 100% replacement (R-100%). Diets were formulated according to the BR-CORTE system to achieve an ADG of 1.3 kg and to contain 130 g CP/kg DM. The diets consisted of 20% corn silage and 80% concentrate that was formulated with ground corn, soybean meal and/or urea, ammonium sulfate, mineral mix, and virginiamycin. All animals were fed for ad libitum intake using an electronic feeder (INTERGADO, Intergado Ltd., Contagem, Minas Gerais, Brazil) and individual daily feed intake was recorded. The bulls were weighed at the beginning and end and every 28 d throughout the finishing period. Data were analyzed using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC) assuming the significance level of 0.05. There was no influence on final BW (P = 0.39), DMI (P = 0.22), ADG (P = 0.47), or feed efficiency (P = 0.98; Table 1). These results suggest that SBM can be replaced with urea and may be used as a strategy to reduce diet costs for Nellore × Red Angus crossbred bulls without affecting DMI, ADG, and feed efficiency.