Relationships of genomic estimated breeding values for age at puberty, birth weight, and growth during development in normal cyclic and acyclic gilts

Authors: WIJESENA, HIRUNI - Orise Fellow; Nonneman, Danny - Dan; Rohrer, Gary; Lents, Clay

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2023
Publication Date: 8/11/2023
Citation: Wijesena, H.R., Nonneman, D.J., Rohrer, G.A., Lents, C.A. 2023. Relationships of genomic estimated breeding values for age at puberty, birth weight, and growth during development in normal cyclic and acyclic gilts. Journal of Animal Science. 101. Article skad258. https://doi.org/10.1093/jas/skad258.
DOI: https://doi.org/10.1093/jas/skad258

Interpretive Summary: Gilts failing to display estrus (sexual behavior) are culled from the breeding herd. Gilts fail to display estrus because of sexual immaturity or silent ovulation. It is important to understand these conditions to improve gilt development. Scientists at Clay Center, Nebraska, compared how body weight and growth rate affect this condition in gilts. Researchers found that sexually immature gilts weighed more at birth but gilts with silent ovulation grew faster in production than their littermates. Producers should avoid selecting gilts with the smallest and largest birth weight as replacements. They could reduce silent ovulation by avoiding the fastest growing gilts in production as replacements.

Technical Abstract: Managing replacement gilts to reach optimal body weight and growth rate for boar stimulation and first breeding is a key component for sow reproductive longevity and producer profitability. Failure to display pubertal estrus remains a major reason that gilts are culled from the herd. Puberty is metabolically gated so evaluating phenotypic and genetic relationships between birth weight and growth traits with age at puberty and acyclicity can provide valuable insight for efficient gilt development. Data on litter of origin of the gilt, average daily gain at different stages of development, and age at puberty were available for age matched cyclic (n = 4,861) and acyclic gilts (prepubertal anestrus, n = 578; behavioral anestrus, n = 428). Genomic estimated breeding values were predicted for each trait using genomic best linear unbiased prediction. Primiparous sows produced more acyclic gilts than multiparous sows (P < 0.05). Accounting for effects of parity and litter size, prepubertal anestrus gilts were heavier at birth and behaviorally anestrus gilts grew faster during finisher period compared to cyclic gilts (P < 0.05), reflecting possible prenatal programming that negatively affects optimal pubertal development and antagonistic effects between adolescent growth and expression of estrus. Regression of phenotypic age at puberty with lifetime growth rate (birth to selection) showed a negative linear relationship whereas genomic estimated breeding values showed a negative quadratic relationship indicating that gilts with the least and greatest growth are less optimal as replacements. The slopes of these relationships are small with low negative phenotypic (r = -0.06) and genetic correlations (r = -0.13). The addition of data from acyclic gilts did not substantially change the estimates for genetic relationships between growth and pubertal onset. Genome-wide association for lifetime growth rate identified melanocortin 4 receptor gene located in the quantitative trait loci with the largest effect, but there was no overlap of these significant loci with QTL identified for age at puberty. Although this study identified differences in birth weight and growth rate between cyclic and acyclic gilts the genetic relationships are weak. Avoiding the smallest and largest gilts in a cohort could result in gilts with optimal development and reduce the proportion of replacement gilts that are acyclic.