Menegassi Silvio Renato Oliveira, Pereira Gabriel Ribas, Bremm Carolina, Koetz Celso, Lopes Flávio Guiselli, Fiorentini Eduardo Custódio, McManus Concepta, Dias Eduardo Antunes, da Rocha Marcela Kuczynski, Lopes Rubia Branco, Barcellos Júlio Otávio Jardim
Department of Animal Science, Federal University of Rio Grande do Sul, Av. Bento Gonçalves, n.: 7.712, Porto Alegre, RS, 91540-000, Brazil.
Animal Production Department, FEPAGRO, Porto Alegre, RS, 90130-060, Brazil.
Int J Biometeorol. 2016 Nov;60(11):1787-1794. doi: 10.1007/s00484-016-1167-2. Epub 2016 Apr 11.
The aim of this study was to evaluate the bioclimatic thermal stress assessed by Equivalent Temperature Index (ETI) and Temperature Humidity Index (THI) on Braford and Nellore bulls sperm quality during the reproductive seasons at the tropical region in the Brazilian Pantanal. We used 20 bulls aged approximately 24 months at the beginning of the study. Five ejaculates per animal were collected using an electroejaculator. Temperature, air humidity, and wind speed data were collected every hour from the automatic weather station at the National Institute of Meteorology. Infrared thermography images data were collected to assess the testicular temperature gradient in each animal. Data were analyzed with ANOVA using MIXED procedure of SAS and means were compared using Tukey's HSD test. The THI and ETI at 12 days (epididymal transit) were higher in January (89.7 and 28.5, respectively) and February (90.0 and 29.0, respectively) compared to other months (P < 0.01). Total seminal defects differ only in Bradford bulls between the months of November and February. Nellore bulls had lower major defects (MaD) and total defects (TD) compared to Braford. Nellore bulls showed correlation between minor defects (MiD) and THI for 30 days (0.90) and 18 days (0.88; P < 0.05). Braford bulls showed correlation for MaD (0.89) in ETI for 12 days (P < 0.05). Infrared thermography showed no difference between animals. Reproductive response to environmental changes is a consequence of Nellore and Braford adaptation to climate stress conditions. Both THI and ETI environmental indexes can be used to evaluate the morphological changes in the seminal parameters in Nellore or Braford bulls; however, more experiments should be performed focusing on larger sample numbers and also in reproductive assessment during the consecutive years to assess fertility potential.
本研究的目的是评估在巴西潘塔纳尔湿地热带地区的繁殖季节，通过等效温度指数（ETI）和温湿度指数（THI）评估的生物气候热应激对布拉福德公牛和内洛尔公牛精子质量的影响。研究开始时，我们使用了20头年龄约24个月的公牛。使用电刺激采精器，每头动物采集5次射精样本。每小时从国家气象研究所的自动气象站收集温度、空气湿度和风速数据。收集红外热成像图像数据，以评估每头动物的睾丸温度梯度。使用SAS的MIXED程序进行方差分析，并使用Tukey's HSD检验比较均值。与其他月份相比，1月份（分别为89.7和28.5）和2月份（分别为90.0和29.0）的12天（附睾运输期）的THI和ETI更高（P < 0.01）。11月至2月期间，仅布拉福德公牛的精液总缺陷存在差异。与布拉福德公牛相比，内洛尔公牛的主要缺陷（MaD）和总缺陷（TD）较低。内洛尔公牛在30天（0.90）和18天（0.88；P < 0.05）时，次要缺陷（MiD）与THI之间存在相关性。布拉福德公牛在12天的ETI中，MaD与THI存在相关性（0.89；P < 0.05）。红外热成像显示动物之间没有差异。内洛尔公牛和布拉福德公牛对环境变化的生殖反应是它们适应气候应激条件的结果。THI和ETI这两个环境指数均可用于评估内洛尔公牛或布拉福德公牛精液参数的形态变化；然而，应进行更多实验，重点关注更大的样本数量，并在连续几年中进行生殖评估，以评估生育潜力。
