This study investigated the effects of growth rates and compensatory growth on puberty attainment in Nellore heifers. Nellore heifers (n = 120), weaned at 8 ± 0.75 mo of age, were blocked by sire and BW (180 ± 8.6 kg) and assigned randomly to receive 1 of 4 treatments over a 10-mo period. Treatments included ad libitum feeding (high gain, HG), feed intake to gain 0.6 kg/d (medium gain, MG), restricted feeding (0.2 kg/d) for 4 mo followed by ad libitum feeding for 6 mo (compensatory gain, CG), and alternating periods of ad libitum and restricted feeding for 2 mo each throughout the trial (alternated CG, ACG). Puberty was assessed weekly by transrectal ultrasonography. Blood samples were collected at 8, 11, and 18 mo of age and at puberty to determine circulating concentrations of leptin. At 18 mo of age, nonpubertal heifers were treated with a puberty induction protocol using an intravaginal progestin device. There was no treatment effect (P = 0.17) on the percentage of heifers pubertal by 18 mo of age (HG: 66, MG: 40, CG: 58, and ACG: 52%), BW at puberty, and age at puberty. However, HG heifers had higher ADG (P < 0.01), dry matter intake (P < 0.01), and leptin concentrations (P = 0.03) than heifers from other groups. The response to the puberty induction protocol was similar (P = 0.90) among treatments. Regarding sire effects (genetic effects), there was an effect (P = 0.03) on the percentage of heifers pubertal by 18 mo of age and a tendency (P = 0.07) of sire effect in response to the puberty induction protocol. Compensatory growth appears to be an effective managerial approach to decrease feeding costs and stimulate puberty in Nellore heifers.

本研究调查了生长速度和补偿性生长对 Nellore 小母牛青春期实现的影响。Nellore 小母牛 (n = 120) 在 8 ± 0.75 月龄断奶，被公牛和体重 (180 ± 8.6 kg) 阻断，并在 10 个月内随机分配接受 4 次治疗中的 1 次。处理包括随意饲喂（高增重，HG），采食量增重 0.6 kg/d（中等增重，MG），限制饲喂（0.2 kg/d）4 个月，然后随意饲喂 6 个月（补偿性增重， CG），以及在整个试验中交替随意进食和限制喂养各 2 个月（交替 CG、ACG）。每周通过经直肠超声检查评估青春期。在 8、11 和 18 个月以及青春期收集血液样本以确定瘦素的循环浓度。在 18 个月的年龄，使用阴道内孕激素装置通过青春期诱导方案治疗非青春期小母牛。没有治疗效果（P = 0.17）关于 18 个月龄（HG：66，MG：40，CG：58 和 ACG：52%）、青春期体重和青春期年龄的青春期小母牛的百分比。然而，与其他组的小母牛相比，HG 小母牛的 ADG ( P < 0.01)、干物质摄入量 ( P < 0.01) 和瘦素浓度 ( P = 0.03) 更高。治疗之间对青春期诱导方案的反应相似（P = 0.90）。关于父系效应（遗传效应），对 18 个月龄前青春期小母牛的百分比有影响（P = 0.03）和趋势（P= 0.07) 对青春期诱导方案的反应。补偿性生长似乎是一种有效的管理方法，可以降低 Nellore 小母牛的饲养成本并刺激青春期。