Evaluation of on-farm indicators of gilt reproductive performance potential at 21 days of age1

Abstract

Selection of replacements for the sow herd is one of the most important facets in swine production. Although our current methods of selection are effective, there is still a large amount of variation in sow reproductive performance traits such as pigs per sow per year (PSY). Therefore, the objective of this study was to determine if on-farm phenotypic traits at 21 d postnatal (PN) or perinatal environmental factors could predict sow reproductive performance. Data were prospectively collected from 2,146 gilts born on a commercial sow production facility and included birth and weaning weights, vulva length and width at 21 d PN, birth and nursing litter size, days nursed, average daily gain from birth to weaning, and age at first estrus. Of the initial animals, 400 (17%) were selected for the sow herd, 353 remained after removal of animals culled for non-reproductive reasons. Animals were assigned to 1 of 5 reproductive performance categories based on observation of estrus or pigs per sow per year (PSY) across two farrowings: High Fertility (HF; 23%; n = 82; ≥26 PSY), Middle Fertility (MF2; 12%; n = 43; 20–25 PSY), Low Fertility (MF3; 15%; n = 54; <20 PSY), Infertile-Estrus (IFe; 10%; n = 36; estrus, no pregnancy), and Infertile-No Estrus (IFno; 39%; n = 138; no estrus, no pregnancy). Generalized linear model analysis indicated vulva width (P = 0.03) was related to PSY, however, it only explained 1.5% of the total variation in PSY. To determine if preweaning variables were predictive of gilt fertility outcome, animals were grouped as those that became pregnant (n = 179) or not (n = 174). Vulva width tended to be greater in fertile animals versus infertile (P = 0.07). Binomial regression analysis revealed a positive relationship between vulva width and gilt fertility, however, this relationship is not strong enough to make sow herd selection decisions.

Genome-Wide Association Study Identified a Quantitative Trait Locus and Two Candidate Genes on Sus scrofa Chromosome 2 Affecting Vulvar Traits of Suhuai Pigs

“…Vulvar width is the distance from the leftmost to the rightmost end of the widest part of the vulva. The measurement rules of vulvar length and width were consistent with that of Mills et al [ 10 ]. Vulvar angle mainly referred to the angle between the straight line, formed by the bottom of the vulva and the bottom of the vulva fissure, and the vulva fissure ( Supplementary Figure S1 ).…”

Morphometric changes on the vulva from proestrus to oestrus of nulliparous and multiparous HYPERPROLIFIC sows

“…Studies of the morphometric changes of the vulva have also been carried out both to establish a correlation with gilts puberty (Graves et al, 2020) and to identify gilts with a higher reproductive potential (Romoser et al, 2020;Mills et al, 2020) changes to onset of oestrus as in our case. In both, gilts and sows, the differences between proestrus and oestrus on vulvar metrics were significant in all measurements.…”

Mutual Relationship between Litter Size and Weaning to First Service Interval in the Sow

“…The profit of swine breeding farms relies largely on the reproductive performance of the sows (Mills et al 2020;Guan et al 2021). In recent decades, the swine reproductive performance has increased substantially (Ward et al 2020;Ju et al 2022) by elevating the number of pigs weaned per sow per year from 20 to 30 and the future figure may reach 40 (Koketsu et al 2017).…”