Díaz Ramiro F, Galina Carlos S, Estrada Sandra, Montiel Felipe, Castillo Gloriana, Romero-Zúñiga Juan José
Escuela de Medicina Veterinaria, Universidad San Francisco de Quito, Diego de Robles S/n, Cumbayá, Ecuador.
Departamento de Reproducción, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México DF, Mexico.
Vet Med Int. 2018 Jul 24;2018:2360430. doi: 10.1155/2018/2360430. eCollection 2018.
In order to measure the influence of the temperature-humidity index (THI) and the variation of fat thickness on reproductive performance, ninety-two cows kept under grazing conditions were used in two farms in Veracruz (Mexico) and Puntarenas (Costa Rica). THI was calculated with the average environmental temperature and relative humidity. Measurements of fat thickness (FAT) were taken two weeks apart from the last trimester of gestation to approximately 80 days postpartum (dpp). Natural breeding was used in both farms. Time to conception was calculated based on the interval from days at risk to conception (DRC), which had to be at least 28 dpp. THI was between 65.4 ± 2.9 and 73.2 ± 1.5 in Veracruz and 75.4 ± 0.26 and 76.5 ± 0.55 in Puntarenas. Variations in THI were observed in Puntarenas whereas in Veracruz THI variations were more prominent. In Veracruz, loss of fat during the last trimester of gestation was on average 8.5%, whereas in the postpartum period it was 18.4% (P = 0.042). In Puntarenas, the variation in the last trimester of gestation was on average 18.7% and in the postpartum period was 10.5% (P = 0.012). The relative change in FAT in Veracruz was 36.7%, and in Puntarenas it was 29.3%. Overall, 60% of the cows became pregnant. FAT decreased the interval of DRC (R=0.06; P=0.033) with a high relationship (R=0.76; P< 0.0001) between THI and time to conception, in both farms. In conclusion, THI levels influence the reproductive performance in early postpartum period affecting DRC.
为了测定温湿度指数（THI）和脂肪厚度变化对繁殖性能的影响，在墨西哥韦拉克鲁斯州和哥斯达黎加蓬塔雷纳斯市的两个农场中，选用了92头处于放牧条件下的奶牛。THI根据环境平均温度和相对湿度计算得出。在妊娠最后三个月至产后约80天（dpp）期间，每隔两周测量一次脂肪厚度（FAT）。两个农场均采用自然配种。受孕时间根据从有受孕风险天数到受孕（DRC）的间隔来计算，DRC必须至少为产后28天。韦拉克鲁斯州的THI在65.4±2.9至73.2±1.5之间，蓬塔雷纳斯市的THI在75.4±0.26至76.5±0.55之间。蓬塔雷纳斯市观察到THI有变化，而韦拉克鲁斯州的THI变化更为显著。在韦拉克鲁斯州，妊娠最后三个月期间的脂肪损失平均为8.5%，而在产后期间为18.4%（P = 0.042）。在蓬塔雷纳斯市，妊娠最后三个月期间的变化平均为18.7%，产后期间为10.5%（P = 0.012）。韦拉克鲁斯州FAT的相对变化为36.7%，蓬塔雷纳斯市为29.3%。总体而言，60%的奶牛怀孕。在两个农场中，FAT均缩短了DRC间隔（R = 0.06；P = 0.033），THI与受孕时间之间存在高度相关性（R = 0.76；P < 0.0001）。总之，THI水平影响产后早期的繁殖性能，对DRC产生影响。
