Performance of Nellore calves in tropical pasture consuming different types of concentrated supplements

ABSTRACT The use of different types of concentrated supplements on the performance of Nellore calves grazing Urochloa brizantha cv. Marandu in the dry season was evaluated. The experiment was conducted on 24 ha divided into 12 paddocks. Seventy-two calves with initial body weight (BW) 176±14kg for 140 days of experiment were used. Evaluated treatments included: Mineral, Salt+urea (mineral with 30% urea), Protein (supplementation with 45% crude protein (CP) and 46% total digestible nutrients (TDN)); and Protein+energy (with 28% CP and 73% TDN). The Mineral, Salt+urea, and Protein were offered ad libitum, and the Protein+energy 5g/kg BW. Protein+energy showed the highest (P< 0.05) intake (3.66g/kg BW) followed by the Protein (1.61), Salt+urea (0.36), and Mineral (0.32). The two latter supplements were not significantly different (P> 0.05). The highest (P< 0.05) average daily gain (ADG, kg/day) was observed in the Protein+energy (0.074). Average daily gains for the Protein and Salt+urea (0.014 and -0.024, respectively) were not significantly different (P> 0.05), but were significantly higher (P< 0.05) than the Mineral (-0.085). Therefore, during the dry season, to prevent the loss of bovine weight the supplements must supply in addition to minerals, also energy, non-protein nitrogen (NNP), and true protein.

摘要：本试验旨在评估旱季饲喂不同类型浓缩补料对放牧于马兰杜品种布鲁桑蒂臂形草（Urochloa brizantha cv. Marandu）草地的内洛尔肉牛犊（Nellore calves）生产性能的影响。试验在24公顷的牧场地块上开展，共划分为12个放牧小区。试验选用72头初始体重（body weight, BW）为176±14kg的肉牛犊，试验周期为140天。供试处理共4组：矿物质补料组、盐+尿素组（添加30%尿素的矿物质补料）、蛋白质补料组（补料粗蛋白（crude protein, CP）含量为45%，总可消化养分（total digestible nutrients, TDN）含量为46%）以及蛋白质+能量补料组（粗蛋白含量28%，总可消化养分含量73%）。其中矿物质补料、盐+尿素补料及蛋白质补料采用自由采食（ad libitum）方式饲喂，蛋白质+能量补料按5g/kg体重（BW）的剂量饲喂。各组补料采食量表现为：蛋白质+能量补料组采食量最高（3.66g/kg体重，P<0.05），其次依次为蛋白质补料组（1.61g/kg体重）、盐+尿素补料组（0.36g/kg体重）与矿物质补料组（0.32g/kg体重）；后两组补料采食量无显著差异（P>0.05）。蛋白质+能量补料组的平均日增重（average daily gain, ADG）最高，为0.074kg/天（P<0.05）；蛋白质补料组与盐+尿素补料组的平均日增重分别为0.014kg/天与-0.024kg/天，两组间无显著差异（P>0.05），但二者的平均日增重均显著高于矿物质补料组（-0.085kg/天，P<0.05）。综上，旱季期间若要避免肉牛体重流失，补料除需提供矿物质外，还需补充能量、非蛋白氮（non-protein nitrogen, NNP）及真蛋白质。