Department of Animal Science, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand.
Department of Animal Science, Faculty of Agriculture, Khon Kaen University, Khon Kaen 40002, Thailand; Network Center for Animal Breeding and Omics Research, Khon Kaen University, Khon Kaen 40002, Thailand.
Poult Sci. 2024 Nov;103(11):104205. doi: 10.1016/j.psj.2024.104205. Epub 2024 Aug 14.
Grandparent roosters are crucial in poultry breeding programs and significantly influence future bird generations' genetic makeup and performance. However, these roosters face considerable challenges from heat stress, which can adversely affect their reproductive performance, semen quality, and overall health and welfare. Our study aimed to investigate the effects of heat stress on the genetics of semen characteristics, identify the appropriate temperature and humidity indices (THI), and determine the threshold point of heat stress to prevent thermal stress. We analyzed data from 3,895 records of 242 Thai native grandparent roosters in conjunction with the THI using 7 THI functions and the regression method. The threshold point of heat stress, genetic parameters, rate of decline of semen characteristics per level of THI, estimated breeding values and selection index values were analyzed using the multivariate test-day model in the AIREML and BLUPF90 programs. Based on the regression coefficient and statistical criteria of the lowest -2logL and AIC values, the results showed that a THI of 78 was considered the threshold point of heat stress. The estimated heritability values ranged from 0.023 to 0.032, 0.066 to 0.069, 0.047 to 0.057, and 0.022 to 0.024 for mass movement, semen volume, sperm concentration, and the semen index, respectively. The reduction rates of mass movement, semen volume, sperm concentration, and semen index at a THI of 78 were -0.009, -0.003, -0.170, and -0.083 per THI, respectively. The genetic correlations among the semen traits were moderately to strongly positive and ranged from 0.562 to 0.797. The genetic correlations between semen traits and heat stress were negative and ranged from -0.437 to -0.749. The permanent environmental correlations among the semen traits (0.648-0.929) were positive and greater than the genetic correlations. Permanent environmental correlations between semen traits and heat stress were negative and ranged from -0.539 to -0.773. The results of the selection indices showed that the higher the selection intensity was, the greater the degree to which the selection index corresponded to genetic progress. The recommendation for animal genetic selection is that the top 10% is appropriate because it seems most preferred. Therefore, using a multivariate test-day model and selection index for the high genetic potential of semen traits and heat tolerance in Thai native grandparent roosters makes it possible to achieve genetic assessment in a large population.
祖父代公鸡在家禽养殖计划中至关重要，它们显著影响着未来鸟类世代的遗传构成和表现。然而，这些公鸡面临着来自热应激的巨大挑战，这可能会对它们的繁殖性能、精液质量以及整体健康和福利产生不利影响。我们的研究旨在探讨热应激对精液特征遗传的影响，确定合适的温度和湿度指数（THI），并确定防止热应激的热应激阈值。我们使用 7 种 THI 函数和回归方法，结合 THI，分析了 242 只泰国本地祖父代公鸡的 3895 个记录的数据。使用 AIREML 和 BLUPF90 程序中的多元测试日模型分析了热应激的阈值、遗传参数、精液特征随 THI 水平下降的速率、估计育种值和选择指数值。根据回归系数和最低-2logL 和 AIC 值的统计标准，结果表明 THI 为 78 时被认为是热应激的阈值。估计的遗传力值范围分别为 0.023 至 0.032、0.066 至 0.069、0.047 至 0.057 和 0.022 至 0.024，用于质量运动、精液量、精子浓度和精液指数。THI 为 78 时，质量运动、精液量、精子浓度和精液指数的下降率分别为每 THI 下降 0.009、0.003、-0.170 和-0.083。精液特征之间的遗传相关性从中等到强，范围为 0.562 至 0.797。精液特征与热应激之间的遗传相关性为负，范围为-0.437 至-0.749。精液特征之间的永久环境相关性（0.648-0.929）为正且大于遗传相关性。精液特征与热应激之间的永久环境相关性为负，范围为-0.539 至-0.773。选择指数的结果表明，选择强度越高，选择指数与遗传进展的对应程度就越高。动物遗传选择的建议是选择前 10%，因为这似乎是最受欢迎的。因此，在泰国本地祖父代公鸡中使用多元测试日模型和选择指数来评估精液特征的高遗传潜力和耐热性，可以实现对大量群体的遗传评估。
