A meta-analysis of energy and protein requirements for maintenance and growth of Nellore cattle
A meta-analysis of energy and protein requirements for maintenance and growth of Nellore cattle
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DOI：
10.2527/jas.2007-0309
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发表时间：
2008-07-01
影响因子：
3.3
通讯作者：
Valadares-Filho, S. C.
中科院分区：
文献类型：
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作者：
Chizzotti, M. L.;Tedeschi, L. O.;Valadares-Filho, S. C.
采用荟萃分析方法测定了内洛尔纯种和内洛尔与博斯金牛杂交的生长公牛、阉牛和小母牛的NE和净蛋白质需要量。收集了16个比较屠宰研究（n = 389只动物）的数据库，以提供足够的信息来建立方程，以预测维持（NPm）和生长（NPg）对NEm、NEg和净蛋白的需求。使用随机系数模型分析数据，将研究视为随机效应，将性别和阉割状态（公牛、阉牛和小母牛，n分别为262、103和24）和品种视为固定效应。不同性别、去势和品种对NEm的需取量无显著差异（P = 0.73）。综合数据表明，空体重（EBW）的NEm需要量为75千卡/公斤（0.75），NEm的代谢能利用效率为0.67。NEg需取量在性别和去势之间存在差异（P = 0.009），在品种之间存在差异（P = 0.06）。公牛的NEg需要量为0.0514 × EBW0.75 × EWG(1.070)；转向组为0.0700 x EBW0.75 x EWG(1.070)；犊牛增重为0.0771 × EBW0.75 × EWG(1.070)，其中EWG = EBW增重（kg/d）。代谢能对NEg的部分利用效率在性别、去势和品种间无显著差异（P = 0.33），平均为0.44。不同性别、去势和品种对NPm的需要量差异不显著（P = 0.59）；总NPm需要量为1.74 g。kg(-0.75) EBW。d(1)。维持所需的总MP量为2.59 g。kg（-0.75）体重。d(1)。NPg需取量（g/d）在性别、去势和品种间无显著差异（P = 0.59）；总方程为EWG x [217 - (12.8 x RE/EWG)]，其中RE =保留能（Mcal/d）。随着RE在增重（REc, Mcal/kg EWG）中的含量的增加，以蛋白质形式沉积的RE百分比（% REp）呈指数下降。由于没有观察到研究效应，我们汇总了所有研究的数据，预测% REp的总体方程为10.1 + 167e（(-0.66 x REc)）。我们的研究结果不支持公牛比阉牛和小母牛需要更多NEm的假设。同样，公牛、阉牛和小母牛对NPm的需求也没有显著差异。然而，阉牛对NEg的需要量高于公牛，低于母牛。尽管% REp与EWG中的能量浓度呈负相关，但我们的研究结果表明，公牛、阉牛和小母牛对NPg的需求没有差异。
A meta-analysis was conducted to determine NE and net protein requirements of growing bulls, steers, and heifers of Nellore purebred and Nellore x Bos taurus crossbreds. A database of 16 comparative slaughter studies (n = 389 animals) was gathered to provide enough information to develop equations to predict the requirements of NEm, NEg, and net protein for maintenance (NPm) and growth (NPg). The data were analyzed using a random coefficients model, considering studies as random effects, and sex and castrate status (bulls, steers, and heifers; n = 262, 103, and 24, respectively) and breeds as fixed effects. There were no differences in NEm requirements among sex and castrate status (P = 0.73) and breeds (P = 0.82). The combined data indicated a NEm requirement of 75 kcal/kg(0.75) of empty BW (EBW) with a partial efficiency of use of ME for NEm of 0.67. The NEg requirement was different (P = 0.009) among sex and castrate status and tended (P = 0.06) to be different among breeds. The equation for NEg requirement for bulls was 0.0514 x EBW0.75 x EWG(1.070); for steers, it was 0.0700 x EBW0.75 x EWG(1.070); and for heifers, it was 0.0771 x EBW0.75 x EWG(1.070), where EWG = EBW gain (kg/d). The partial efficiency of use of ME for NEg was not different among sex and castrate status (P = 0.33) and breeds (P = 0.20) and averaged 0.44. There were no differences in NPm requirement among sex and castrate status (P = 0.59) and breeds (P = 0.92); the overall NPm requirement was 1.74 g of NP . kg(-0.75) of EBW . d(-1). The overall MP requirement for maintenance was 2.59 g of MP. kg(-0.75) EBW . d(-1). The NPg requirement (g/d) was not different among sex and castrate status (P = 0.59) and breeds (P = 0.14); the overall equation was EWG x [217 - (12.8 x RE/EWG)], where RE = retained energy (Mcal/d). The percentage of RE deposited as protein (% REp) decreased exponentially as the content of RE in the gain (REc, Mcal/kg of EWG) increased. Because no study effect was observed, we pooled the data across studies and the overall equation to predict % REp was 10.1 + 167e((-0.66 x REc)). Our results do not support the hypothesis that bulls have greater NEm requirements than steers and heifers. Likewise, no significant differences in the NPm requirements among bulls, steers, and heifers were detected. Nonetheless, the NEg requirement of steers was greater than bulls and less than heifers. Even though the % REp was negatively correlated with the concentration of energy in the EWG, our findings indicated no differences in NPg requirement among bulls, steers, and heifers.