Phenotypic and genetic correlations between gilt estrus, puberty, growth, composition, and structural conformation traits with first-litter reproductive measures

Abstract

The objective was to estimate correlations of gilt estrus, puberty, growth, composition, and structural conformation traits with first-litter reproductive measures. Four groups of gilts (n = 1,225; Genetic Improvement Services of NC, Newton Grove, NC) entered the NC Swine Evaluation Station (Clayton, NC) averaging 162 d of age and were observed daily for symptoms of estrus. Once symptoms of first estrus were observed in 70% of gilts, recording of symptoms of estrus in all gilts occurred every 12 h for 30 d, utilizing fence-line boar contact. Subjective estrous traits were maximum and total strength of standing reflex, as observed with and without the presence of a boar, and strength of vulva reddening and swelling. Objective estrous traits consisted of vulva redness, vulva width, length of estrus, and age at puberty. Growth and composition traits included BW at puberty, days to 114 kg, and 10th rib backfat and LM area at 114 kg and at puberty. Subjective structural conformation traits were muscle mass, rib width, front leg side view, rear leg side view, front legs front view, rear legs rear view, and locomotion. First-litter sow traits included if gilt farrowed (Stay), age at first farrowing (AFF), total number of piglets born (TNB), and weaning to conception interval (WCI). Variance components were estimated using an animal model with AIREMLF90 for linear traits and THRGIBBS1F90 for categorical traits. Heritability estimates for Stay, AFF, and TNB were 0.14, 0.22, and 0.02, respectively. Genetic correlations between length of estrus, the standing reflex traits, and age at puberty with Stay were 0.34, 0.34 to 0.74, and -0.27, respectively, and with AFF were -0.11, -0.04 to -0.41, and 0.76, respectively. Days to 114 kg had genetic associations with Stay, AFF, and TNB of 0.52, -0.25, and -0.08, respectively. Backfat at 114 kg had genetic correlations with Stay, AFF, and TNB of -0.29, 0.14, and 0.47, respectively. Vulva redness and TNB were negatively correlated phenotypically (r = -0.14) and genetically (r = -0.53). Associations between structural conformation traits with Stay, AFF, TNB, and WCI were generally low to moderate and favorable. Selection for longer length of estrus, stronger standing reflex, or younger age at puberty would increase the proportion of gilts that farrow and reduce age at first farrowing.

Reproductive performance of sows selected for divergent social genetic effects for growth

“…In this study, the WEI of +SGE sows (5.4 d) was significantly lower than that of -SGE sows (5.9 d; P < 0.01, SEM = 0.08). Based on these results and those reported by Knauer et al (2011), a younger age at first farrowing would reduce the WEI. Therefore, +SGE selection would result in younger age at first farrowing and a shorter WEI.…”

“…Knauer et al (2011) reported that selection for longer estrus and a stronger standing reflex reduced the age at first farrowing. Knauer et al (2011) also reported that the superior estrus behavior of females that were younger at puberty was caused by higher peak concentrations of estradiol compared with that of females that were older at puberty.…”

“…Knauer et al (2011) reported that selection for longer estrus and a stronger standing reflex reduced the age at first farrowing. Knauer et al (2011) also reported that the superior estrus behavior of females that were younger at puberty was caused by higher peak concentrations of estradiol compared with that of females that were older at puberty. Among first-litte females, Sterning et al (1998) estimated a negative genetic correlation between age at puberty and the ability to exhibit the standing reflex and ovulate after weaning.…”

“…A younger age at puberty reduces the WEI in gilts and sows (Knauer et al, 2011), which in turn decreases culling for reproductive failure. In this study, the WEI of +SGE sows (5.4 d) was significantly lower than that of -SGE sows (5.9 d; P < 0.01, SEM = 0.08).…”

“…Among first-litte females, Sterning et al (1998) estimated a negative genetic correlation between age at puberty and the ability to exhibit the standing reflex and ovulate after weaning. AFF was determined to be moderately heritable (Serenius 2004;Serenius et al, 2008) and the correlation between individual growth rate and AFF has been shown to vary depending on management method (positive: Knauer et al, 2011, negative: Rydhmer et al, 1995, Serenius and Stalder 2004. The AFF is regulated by age at puberty and management practices.…”