The effect of genotype on feedlot performance, carcass composition, and lean meat quality from commercial pigs

Abstract

A total of 60 female and 54 castrated male progeny of commercial Landrace × Large White F1 sows, backcrossed to Landrace or Large White boars, were slaughtered at an average liveweight of 102 kg. Four same-sex pigs were penned together. Large White sires were homozygous normal (NN) but Landrace sires were heterozygous carriers (Nn), at the halothane locus. Progeny genotypes at the halothane locus were determined by a DNA probe. Barrows grew 136 g d−1 faster (P < 0.0001), reaching market weight 13 d sooner (P < 0.0001) but with 3.2 mm more average back-fat (P < 0.0001) than gilts. Both sexes had similar feed requirements (P = 0.1221). Landrace and Large White-sired pigs had similar growth rate (P = 0.6458) and feed requirements (P = 0.9354), but Large White-sired pigs had 1.33 mm less grade fat thickness (P = 0.0131) and 1.72 more muscle depth (P = 0.0218) than Landrace-sired pigs. Nn pigs required 7 d longer (P < 0.0001) and 22 kg (P = 0.0393) more total feed to reach market weight than NN pigs, but they had 2.6 mm greater muscle depth (P = 0.0008) and had 1% greater commercial lean yield (P = 0.0291). However, meat quality of Nn pigs was reduced when compared with NN pigs. For example, colour reflectance and drip loss were higher (P < 0.0001) and soluble protein was lower (P < 0.0001) among the Nn pigs which also had less intrasmuscular fat (P = 0.0184). The results emphasize that the increased value of the carcass from Nn pigs may be offset by reduced feedlot performance and reduced meat quality, and questions the merit of the use of halothane gene to improve production efficiency in the commercial market. Key words: Swine production, halothane gene, breed effect, Landrace, Large White