S.J. Moeller1, R.S. Emnett, T.J. Baas and K.M. Irvin
The Ohio State University Department of Animal Sciences
Abstract
This study was conducted in response to an industry need to assess the impact of the Rendement Napole (RN) gene on economically important production, carcass and muscle quality traits in a population of widely used Hampshire sires and to estimate the gene frequency within a U.S. population of Hampshire swine. Previous research completed has indicated that the presence of the dominant RN allele is associated with inferior muscle quality attributes. Because the causative mutation for the RN gene is currently unknown, a biochemical test evaluating the Glycolytic Potential (GP) of pork muscle is used to classify animals as carriers (RN-,RN- or RN-,rn+) or negative (rn+,rn+) for the RN gene. In the study, 119 progeny representing 15 purebred Hampshire sires were produced via AI matings to Yorkshire X Landrace F1 females known to be RN negative. Progeny genotype (RN-/rn+ or rn+/rn+) was determined based upon the bimodal distribution of observed GP values taken on post-mortem loin muscle. Sire genotypes and allele frequency calculations were evaluated based upon genotype of the progeny. The gene frequency of the dominant RN- allele in the sires was estimated to be 0.43, a value significantly lower than estimated in European populations, indicating that selection for or against the RN allele is possible. Analysis of genotype differences revealed that loins from RN negative (rn+/rn+) animals had higher, more desirable ultimate pH (P < 0.05), improved loin firmness scores (P < 0.05) and were darker and more desirable for objective measures of loin color (P < 0.07). No differences between genotypes were found for production, carcass or sensory attributes on the population evaluated. The results of this trial indicate that the rn+,rn+ genotype results in improved muscle quality attributes for traits that influence water-holding capacity (ultimate pH) and visual indicators of quality (loin firmness and color) and that selection for the favorable rn+ allele can result in improved muscle quality without detrimental affects on muscle quality, carcass or performance traits.