Moura Ana Beatriz Bossois, Brandão Felipe Zandonadi, Esteves Sérgio Novita, Nunes de Souza Guilherme, Fonseca Jeferson Ferreira da, Pantoja Messy Hannear Andrade, Romanello Narian, Botta Daniela, Giro Alessandro, Garcia Alexandre Rossetto
Faculty of Veterinary Medicine, Fluminense Federal University, Niterói, RJ, Brazil.
Laboratory of Animal Reproduction, Brazilian Agricultural Research Corporation, Embrapa Southeast Livestock (CPPSE/Embrapa), São Carlos, SP, Brazil.
Theriogenology. 2019 Jan 1;123:123-131. doi: 10.1016/j.theriogenology.2018.09.037. Epub 2018 Sep 29.
For different ovine breeds to maximize their reproductive capacity in countries with tropical climate, it is important to evaluate their potential for thermal resilience and consequences on their reproductive traits. Therefore, the objective of this study was to evaluate the effect of thermal environment temperatures of climate seasons in a tropical climate region on the surface temperatures of the scrotum, testicular biometric characteristics, seminal quality and serum testosterone concentration of rams of different genotypes. Breeders of four different genotypes (Dorper, n = 8, Texel, n = 8, Santa Inês, n = 9 and Morada Nova, n = 8) were used throughout the four climate seasons. Higher thermal challenge was recorded in the spring and summer. In the summer increase in scrotal surface temperature was detected by infrared thermography (P < 0.05), mainly in the regions of the distal testicular pole and tail of the epididymis. The animals of the Texel genotype had higher rectal temperature in the summer. In spring, this genotype also had the highest testicular pole (32.2 ± 0.5 °C; P < 0.05) and distal (29.9 ± 0.4 °C; P < 0.05) temperatures and a higher mean testicular temperature (31.7 ± 0.4 °C; P < 0.05). The Morada Nova genotype showed a higher surface temperature gradient between testicular poles (2.96 ± 0.1 °C; P < 0.05), especially in spring. Genotype-dependent thermal sensitivity was detected for the thermal gradient between the testicular poles, reflecting the seminal quality. There was a positive correlation of the thermal gradient between testicular poles with sperm membrane integrity and negative correlation with total sperm defects. The Texel genotype showed less progressive motility and higher percentage of sperm defects. There was no difference in testosterone concentration between genotypes and in the different seasons (P > 0.05). Thus, the indigenous genotypes showed a greater capability to maintain the scrotum-testicular thermoregulation. Dorper animals resembled the indigenous sheep genotypes, in terms of seminal characteristics, unlike Texel animals, which showed lower adaptability and lower seminal quality.
对于不同的绵羊品种，要在热带气候国家最大限度地提高其繁殖能力，评估它们的热适应潜力及其对繁殖性状的影响很重要。因此，本研究的目的是评估热带气候地区气候季节的热环境温度对不同基因型公羊阴囊表面温度、睾丸生物特征、精液质量和血清睾酮浓度的影响。在四个气候季节中使用了四种不同基因型的种公羊（杜泊羊，n = 8；特克塞尔羊，n = 8；圣伊内斯羊，n = 9；莫拉达诺瓦羊，n = 8）。春季和夏季记录到更高的热应激。在夏季，通过红外热成像检测到阴囊表面温度升高（P < 0.05），主要在睾丸远端极和附睾尾部区域。特克塞尔基因型的动物在夏季直肠温度较高。在春季，该基因型的睾丸极温度（32.2±0.5°C；P < 0.05）和远端温度（29.9±0.4°C；P < 0.05）也最高，平均睾丸温度也较高（31.7±0.4°C；P < 0.05）。莫拉达诺瓦基因型在睾丸极之间显示出更高的表面温度梯度（2.96±0.1°C；P < 0.05），尤其是在春季。检测到睾丸极之间的热梯度存在基因型依赖性热敏感性，反映了精液质量。睾丸极之间的热梯度与精子膜完整性呈正相关，与总精子缺陷呈负相关。特克塞尔基因型的精子渐进性活力较低，精子缺陷百分比较高。基因型之间以及不同季节的睾酮浓度没有差异（P > 0.05）。因此，本地基因型显示出更强的维持阴囊 - 睾丸温度调节的能力。就精液特征而言，杜泊羊与本地绵羊基因型相似，而特克塞尔羊则表现出较低的适应性和较低的精液质量。
