Boonkum Wuttigrai, Chankitisakul Vibuntita, Juiputta Jiraporn
Department of Animal Science, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand, 40002; Network Center for Animal Breeding and Omics Research, Khon Kaen University, Khon Kaen, Thailand, 40002.
Department of Animal Science, Faculty of Agriculture, Khon Kaen University, Khon Kaen, Thailand, 40002.
Poult Sci. 2025 May 20;104(8):105321. doi: 10.1016/j.psj.2025.105321.
Temperature and relative humidity indices (THIs) are widely used to study the effects of heat stress on reduced poultry production traits. However, a suitable THI for reproductive traits has not yet been established. This study aimed to develop a novel THI to predict semen traits in native roosters using regression analysis. A total of 242 Thai native grandparent roosters (Pradu Hang Dum) aged 30 weeks were used. Semen was collected weekly for 1 year to assess parameters, including semen volume, mass motility, and sperm concentration. To simplify the evaluation of semen traits, a composite measure termed the "semen index" was developed. This index was calculated by summing the Z-scores of the volume, mass, and concentration of each sample. Simple regression analysis was performed using several statistical criteria to identify the optimal THI function for the dataset and determine the THI threshold that influences changes in semen characteristics. The results indicated that the newly developed THI function (THI_F) offered a better fit for predicting the onset of heat stress than the original THI1, particularly at a THI threshold of 76. The improved fit of THI_F, as demonstrated by the lower values of the sum of squared errors, Akaike information criterion, and Bayesian information criterion, suggests that it provides a more reliable indication of thermal stress affecting reproductive performance. Therefore, the newly developed THI function is a more precise tool for evaluating the effects of thermal stress. This improved index has important applications in genetic selection and breeding strategies aimed at enhancing heat tolerance and reproductive performance in livestock, particularly for improving the resilience of poultry to heat stress, which is crucial for sustaining productivity under challenging environmental conditions.
温度和相对湿度指数（THIs）被广泛用于研究热应激对家禽生产性能下降的影响。然而，尚未确定适合生殖性状的THI。本研究旨在通过回归分析开发一种新的THI来预测本地公鸡的精液性状。总共使用了242只30周龄的泰国本地祖代公鸡（Pradu Hang Dum）。每周采集精液，持续1年，以评估精液量、活力和精子浓度等参数。为了简化精液性状的评估，开发了一种称为“精液指数”的综合指标。该指数通过将每个样本的体积、活力和浓度的Z分数相加来计算。使用几种统计标准进行简单回归分析，以确定数据集中的最佳THI函数，并确定影响精液特征变化的THI阈值。结果表明，新开发的THI函数（THI_F）比原始的THI1更适合预测热应激的开始，特别是在THI阈值为76时。THI_F的拟合度提高，如平方误差总和、赤池信息准则和贝叶斯信息准则的值较低所示，表明它能更可靠地指示影响生殖性能的热应激。因此，新开发的THI函数是评估热应激影响的更精确工具。这种改进的指数在旨在提高家畜耐热性和生殖性能的遗传选择和育种策略中具有重要应用，特别是对于提高家禽对热应激的恢复力，这对于在具有挑战性的环境条件下维持生产力至关重要。
