PSXIII-B-16 Relationship of Genomic Estimated Breeding Values for age at Puberty, Birth Weight, and Growth in Cyclic and Anestrus Gilts

Abstract

Abstract Prebreeding anestrus (failure to express estrus) affects 10-30% of gilts. Two main types of anestrus are delayed puberty (prepubertal anestrus; PPA) and ovulation without behavioral estrus (behavioral anestrus; BA). We hypothesized that growth of cyclic gilts during development is greater than PPA and BA gilts. The objectives of this study were to determine if birth weight and growth differed between cyclic and anestrus gilts and the relationship of age at puberty (AP) with growth. Individual body weights were recorded at birth (BTW), and at 4, 8, and 20 weeks of age for cyclic (n=4,982), PPA (n=578), and BA (n=428) gilts. Because anestrus gilts lack puberty records, genomic best linear unbiased prediction was used to predict genomic estimated breeding values for AP (GEBV-AP) for PPA and BA gilts using AP of cyclic gilts. A mixed model was fit using phenotypic group, sire line, and dam parity (1-4) as fixed effects and contemporary group as a random effect. The PPA gilts had a greater GEBV-AP (P< 0.05) compared with cyclic and BA gilts and were heavier at birth than cyclic gilts (P< 0.05). The BA gilts had a greater lifetime growth rate (LGR; ADG from birth to 20 weeks) than cyclic and PPA gilts (P< 0.05). The LGR and GEBV-AP did not differ between dam parities. Relationship of AP and growth was evaluated using GEBV for cyclic and anestrus gilts in a mixed model regression. A positive relationship between GEBV-AP and GEBV-BTW and a negative relationship between GEBV-AP and GEBV-LGR was observed. Results suggest that earlier attainment of puberty could be improved by avoiding the heaviest gilts at birth and selecting for faster growing gilts during grow-finish. However, the latter could increase the risk for more BA gilts due to possible antagonistic effects of growth on behavioral estrus.The USDA is an equal opportunity provider and employer.