Vélez Leonardo Iván, Flores Manuel Jesús, Hernández Horacio, Vargas-Cruz Alexis A, Avilés Ricardo, Rosales-Nieto Cesar A
Campo Experimental La Laguna, Instituto Nacional de Investigaciones Forestales, Matamoros, México.
Centro de Investigación en Reproducción Caprina (CIRCA), Posgrado en Ciencias Agrarias, Universidad Autónoma Agraria Antonio Narro, Torreón, México.
J Anim Sci. 2025 Jan 4;103. doi: 10.1093/jas/skaf270.
This study aimed to evaluate whether exposure to artificial long-day photoperiods stimulates growth performance in young male goats, either intact or castrated. Forty young male goats (13 wk old), either intact (I) or castrated (C), were assigned to one of two photoperiod treatments: artificial photoperiod (AP; 16h light:8h dark) or natural photoperiod (NP; 12h light:12 dark). Animals were housed individually, and four experimental groups were established: NP-I (n = 10), AP-I (n = 11), NP-C (n = 10), and AP-C (n = 9). Males were weighed weekly; glucose, testosterone, and insulin-like growth factor 1 (IGF-1) concentrations were monitored biweekly; and feed intake was measured every 3 wk from September to February. At 38 wk of age, males were slaughtered to assess carcass yield. Each animal was considered an experimental unit, and the data were analyzed using mixed models and repeated measures of SAS. Goats exposed to AP gained more weight and had greater final body weights than those under NP conditions (P < 0.001). Intact males also gained more weight than castrated males (P < 0.001). Feed intake was greater in AP-treated animals (P < 0.001). Carcass yield was greater in both AP- and I-males compared to NP- and C-males, respectively (P < 0.001). IGF-1 concentration increased in AP- and I-males than in NP- or C-males (P < 0.001), and glucose concentration increased in AP-treated animals compared to those exposed to NP (P < 0.001). Testosterone concentration increased in AP males than in NP males in weeks 15 and 17 (P < 0.01), but not at the other time points (P > 0.05). These findings suggest that exposure to artificial long-day photoperiods increases daily weight gain, feed intake, final body weight, and carcass yield in young male goats, regardless of their reproductive status. These improvements were associated with increased IGF-1 and glucose concentrations, while testosterone concentration remained unaffected.
本研究旨在评估暴露于人工长日照光周期是否会刺激年轻公山羊（完整或阉割）的生长性能。40只13周龄的年轻公山羊，分为完整组（I）或阉割组（C），被分配到两种光周期处理之一：人工光周期（AP；16小时光照：8小时黑暗）或自然光照周期（NP；12小时光照：12小时黑暗）。动物单独饲养，建立了四个实验组：NP-I（n = 10）、AP-I（n = 11）、NP-C（n = 10）和AP-C（n = 9）。每周对公羊称重；每两周监测一次葡萄糖、睾酮和胰岛素样生长因子1（IGF-1）浓度；从9月到2月，每3周测量一次采食量。在38周龄时，对公羊进行屠宰以评估胴体产量。将每只动物视为一个实验单位，并使用SAS的混合模型和重复测量对数据进行分析。与处于NP条件下的山羊相比，暴露于AP的山羊体重增加更多，最终体重更大（P < 0.001）。完整的公羊也比阉割的公羊体重增加更多（P < 0.001）。AP处理的动物采食量更大（P < 0.001）。与NP和C组公羊相比，AP和I组公羊的胴体产量分别更高（P < 0.001）。与NP或C组公羊相比，AP和I组公羊的IGF-1浓度增加（P < 0.001），与暴露于NP的动物相比，AP处理的动物葡萄糖浓度增加（P < 0.001）。在第15周和第17周，AP组公羊的睾酮浓度高于NP组公羊（P < 0.01），但在其他时间点则无差异（P > 0.05）。这些发现表明，暴露于人工长日照光周期可增加年轻公山羊的日增重、采食量、最终体重和胴体产量，无论其生殖状态如何。这些改善与IGF-1和葡萄糖浓度增加有关，而睾酮浓度不受影响。
