Halothane genotype and pork production. 1 Growth, carcass and meat quality characteristics
The effect of the halothane gene on certain growth and meat quality characteristics were investigated by comparing the three known halothane genotypes (NN, Nn, nn). Fifty nine Landrace × Large White pigs (gilts = 25, castrates = 34; NN = 31, Nn = 17, nn = 11) were reared from 27 to 86 kg liveweight, whereafter the pigs were slaughtered and meat and carcass quality characteristics measured. Average daily gain (ADG), days to slaughter and carcass length showed significant genotype × sex interaction. The nn pigs showed the highest ADG and least days to slaughter, followed by the NN and then the Nn pigs. The castrates grew significantly faster with a higher ADG (p < 0.05) and fewer days to slaughter (p < 0.001). Carcass length did not differ for different genotypes or sexes. NN pigs had the highest meat depth, predicted lean meat percentage (LMP) and lowest fat thickness, followed by the Nn and nn pigs. The castrates had a higher fat thickness (p < 0.05) with a resultant lower LMP (p < 0.05) compared to gilts. None of the genotypes or sexes showed differences in chilling loss, but drip loss differed between genotypes (p < 0.05) and sexes (p < 0.001), with nn pigs having the lowest drip loss. The pH1 values differed (p < 0.05) between genotypes, with NN the highest and nn the lowest. No differences in pH24 were observed between genotypes. The pH1 and pH24 values did not differ between sexes. Although the presence of the halothane gene positively affected growth rate, this increase in growth rate was largely due to undesirable fat deposition. Furthermore, the gene did not positively affect meat quality (pH1) or carcass quality (LMP). Therefore, the intentional use of the halothane gene is discouraged.