Prediction of postpubertal reproductive potential according to prepubertal body weight, testicular size, and testosterone concentration using multiple regression analysis in Kvrck ram lambs.

摘要

The study was conducted to determine the relationship among prepubertal body weight, testicular size, testosterone concentration, and postpubertal reproductive function in Kvrck lambs (n=15). The body weight, testicular size, and testosterone concentration were measured every 20 days between 60 and 420 days of age. Semen was collected from the rams at 7, 8, 9, 10, 11, 12, 13 and 14 months of age. Data obtained were analysed by best subsets regression model. Results revealed that body weight, scrotal circumference, testicular length, and testosterone levels during the early prepubertal period (days 80, 100, and 120), when combined with each other, determined the postpubertal (days 220, 240, 260 and 280) testicular diameter. Body weight and testosterone at prepubertal ages, either alone or in combination with other variables, were related to semen volume at postpubertal ages (7, 8, 9, 11, and 14 months of age). It is concluded that there is a significant relationship between postpubertal reproduction characteristics and the selection of Kvrck lambs during the prepubertal period (especially between days 80 and 120) according to body weight, testicular characteristics, and testosterone concentrations. It is suggested that selection of lambs at juvenile age will improve the effectiveness of the selection and the economic gain of sheep breeding operations.