T.D. Leeds, K M. Irvin1, and S.J. Moeller
The Ohio State University Department of Animal Sciences
Abstract
The association between the estrogen receptor (ESR) locus and growth, carcass, and developmental traits in swine was investigated in a population of purebred and crossbred Large White and Yorkshire animals. A total of 724 animals were genotyped at the ESR locus (AA, AB, or BB) via a polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) procedure or by pedigree analysis and were measured for traits including teat number (TN), individual birth weight (IBW), weaning weight (WW), age at 240 lb (AGE), average daily gain (ADG), ultrasonic backfat thickness (BF), and loin-muscle area (LMA). WW, AGE, BF, and LMA measurements were adjusted to a standardized weight or age prior to the statistical analysis using guidelines provided by the National Swine Improvement Federation. Data were analyzed using a linear model including the fixed effects of ESR genotype, breed composite, sex, season, and parity and interactions including ESR genotype x breed and ESR genotype x sex. ESR genotype was found to be a significant (P < 0.05) contributor to the phenotypic variance for BF and nominally significant (P < 0.10) for IBW. Animals possessing at least one copy of the B allele had 0.061 ± 0.023 inches more BF than homozygous A animals (P < 0.01). Heterozygous animals were 0.120 ± 0.053 lbs. heavier at birth than the average of the homozygous animals (P < 0.05). There were no detectable ESR genotype effects for TN, WW, AGE, ADG, or LMA (P > 0.10). Results of this study give evidence of a quantitative trait loci (QTL) in the vicinity of the ESR locus affecting BF and IBW. Utilization of the ESR B allele in a marker-assisted selection program for increased litter size, as suggested in previous studies, may have a detrimental effect on BF.