Effect of ewe birth litter size and estimation of genetic parameters on ewe reproductive life traits

作者：Lauren L Hulsman Hanna, J. B. Taylor, Peter Holland, K. A. Vonnahme, Lawrence P. Reynolds, David G. Riley · 发表于：animal · 年份：2023 · DOI：10.1016/j.animal.2023.100900 · 被引用次数：12 · 研究领域：Genetic and phenotypic traits in livestock、Reproductive Physiology in Livestock、Ruminant Nutrition and Digestive Physiology

Ewe lifetime productivity has economic implications for producers because shorter lifetime productivity results in less profit. Productive years of ewes from extensive, range-based systems of the United States West are generally less than ewes from more temperate regions of the United States. Accordingly, ewes from range-based systems, especially those employing shed-lambing strategies, have been selected for increased litter size to offset decreased lifetime productivity. However, the relationship of the ewe’s birth litter size (ELSB) has not been considered a potential contributor to lifetime productivity. Longevity (number of productive years, n = 1 per population) and stayability (probability to survive to the next age; ages 2 to 7 years, n = 6 per population) were investigated to understand ELSB effects on productive life. Columbia, Polypay, Rambouillet, and Targhee breeds were used in this study. Across-breed (n = 11 550) and within-breed (Columbia, n = 4 398; Polypay, n = 4 534; Rambouillet, n = 5 922; Targhee, n = 6 482) analyses were used. Depending on the population, records spanned from 1950 to 2008, where ewe’s birth year was included as a fixed effect in the animal model using restricted maximum likelihood estimation procedures. Fixed effects investigated included ELSB (single-, twin-, or triplet-born) and ewe breed (across-breed analyses only). Regardless of trait or population used, heritability ranged from 0.06 ± 0.02 to 0.34 ± 0.03, where stayability at young...