Bioeconomic evaluation of supplementation strategies of zebuine steers grazing on stockpilled palisade grass in the dry season

SUMMARY The objective of this work was to evaluate different supplementation strategies on supplement intake, behavior, and performance of beef steers grazing stockpiled palisade grass (Urochloa brizantha cv. Marandu) pastures. There was used a completely randomized design trial to test five supplementation strategies: commercial mineral (SM), mineral plus25% of urea (SP), and three multimixtures (45.5% TDN) with 10% (MM10), 15% (MM 15), or 20% (MM20) of urea. Twenty zebuine steers weighting 300±24.9 kg of initial body weight, being four animals per treatment, were raised on five paddocks of 3.4 hectares under weekly rotation, from July to October of 2010. Data were submitted to ANOVA, using Tukey′s test to compare average values (P≤0.05); however, economic analysis determined the best strategy. Supplementation did not affect the grazing or rumination/resting time (P>0.05). The intake of supplements was affected (P摘要 本研究旨在评估不同补饲策略对放牧贮备型马兰杜类臂形草（Urochloa brizantha cv. Marandu）牧场的肉牛阉牛的补饲采食量、行为表现及生产性能的影响。本试验采用完全随机设计，共设置5种补饲策略：商业矿物补料（SM）、添加25%尿素的矿物补料（SP），以及3种总消化养分（Total Digestible Nutrients, TDN）含量为45.5%的复合补料，其尿素添加比例分别为10%（MM10）、15%（MM15）与20%（MM20）。试验选取初始体重为300±24.9 kg的瘤牛阉牛共20头，每个处理组分配4头，于2010年7月至10月期间，在5个面积为3.4公顷的放牧小区内实施每周轮换的轮牧模式。试验数据采用方差分析（Analysis of Variance, ANOVA）进行统计处理，以Tukey检验进行组间均值比较（P≤0.05）；同时通过经济分析确定最优补饲策略。结果表明，补饲策略对肉牛的放牧时间、反刍/休息时间无显著影响（P>0.05）。补饲采食量则受补饲策略的显著影响（P