Ortega Román Maza, Paulino Mário Fonseca, Detmann Edenio, Rennó Luciana Navajas, Moreno Deilen Sotelo, Márquez David Contreras, de Almeida Daniel Mageste, de Melo Luciano Prímola, Moura Felipe Henrique
Department of Animal Science, Universidade Federal de Viçosa, Avenida P.H. Rolfs, s/n°, Viçosa, Minas Gerais, CEP 36570-000, Brazil.
Trop Anim Health Prod. 2020 May;52(3):1013-1022. doi: 10.1007/s11250-019-02095-7. Epub 2020 Jan 30.
The objective of this study was to evaluate the effects of nutritional strategies on productive and nutritional performance, metabolic profile, and ovarian activity in heifers under grazing in the tropics in Brazil. Forty Nellore heifers averaging 8.5 ± 0.06 months and 248.6 ± 3.3 kg body weight (BW) were distributed in a completely randomized 2 × 2 factorial design with four treatments and ten replicates. The evaluated strategies consisted of different amounts of energetic-protein supplement: (1) 4 g/kg of BW of supplement in the pre-weaning and post-weaning; (2) 4 g/kg of BW of supplement pre-weaning and 6 g/kg in the post-weaning; (3) 6 g/kg of BW of supplement in the pre-weaning and 4 g/kg of BW in the post-weaning and; (4) 6 g/kg of BW of supplement in the pre-weaning and post-weaning. Crude protein (CP) and organic matter (OM) intake were increased (P < 0.05) by increasing the amounts of supplement in the post-weaning. Additionally, increasing supplement amounts in the post-weaning increased the digestibility of OM and CP (P < 0.05). Means insulin and glucose concentrations were greater (P < 0.05) for heifers that received higher amounts of supplement in the post-weaning. Average daily gain and fat thickness in the rump were increased (P < 0.05) by increasing supplement amounts in the post-weaning. Amounts of supplement did not influence the body growth of heifers. However, follicular number, diameter, and progesterone concentration were greater (P < 0.05) for heifers that received higher amounts of supplement in the post-weaning. In summary, increasing supplement amounts in the post-weaning improve the performance, energy and metabolic status, and ovarian activity in beef heifers under grazing in the tropics. Due to higher intake of supplement, the heifers receiving 6 g/kg of BW post-weaning had greater responses, independently of the supplement amount received pre-weaning.
本研究的目的是评估营养策略对巴西热带地区放牧小母牛生产性能、营养状况、代谢特征和卵巢活动的影响。40头平均年龄8.5±0.06个月、体重248.6±3.3千克的内洛尔小母牛，按照完全随机的2×2析因设计分为4种处理，每种处理10个重复。评估的策略包括不同量的能量 - 蛋白质补充剂：（1）断奶前和断奶后均为4克/千克体重的补充剂；（2）断奶前4克/千克体重的补充剂，断奶后6克/千克体重的补充剂；（3）断奶前6克/千克体重的补充剂，断奶后4克/千克体重的补充剂；（4）断奶前和断奶后均为6克/千克体重的补充剂。断奶后增加补充剂的量会使粗蛋白（CP）和有机物（OM）摄入量增加（P<0.05）。此外，断奶后增加补充剂的量会提高OM和CP的消化率（P<0.05）。断奶后接受较高补充剂量的小母牛的平均胰岛素和葡萄糖浓度更高（P<0.05）。断奶后增加补充剂的量会使平均日增重和臀部脂肪厚度增加（P<0.05）。补充剂的量不影响小母牛的身体生长。然而，断奶后接受较高补充剂量的小母牛的卵泡数量、直径和孕酮浓度更高（P<0.05）。总之，断奶后增加补充剂的量可改善热带地区放牧肉用小母牛的生产性能、能量和代谢状况以及卵巢活动。由于补充剂摄入量较高，断奶后接受6克/千克体重补充剂的小母牛反应更大，与断奶前接受的补充剂量无关。
