HALOTHANE GENOTYPE AND PORK PRODUCTION - 1 - GROWTH, CARCASS AND MEATQUALITY CHARACTERISTICS

The effect of the halothane gene on certain growth and meat quality ch aracteristics were investigated by comparing the three known halothane genotypes (NN, Nn, nn). Fifty nine Landrace x 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), d ays to slaughter and carcass length showed significant genotype x sex interaction, The nn pigs showed the highest ADG and least days to slau ghter, followed by the NN and then the Nn pigs. The castrates grew sig nificantly faster with a higher ADG (p < 0.05) and fewer days to slaug hter (p < 0.001). Carcass length did not differ for different genotype s or sexes. NN pigs had the highest meat depth, predicted lean meat pe rcentage (LMP) and lowest fat thickness, followed by the Nn and nn pig s. The castrates had a higher fat thickness (p < 0.05) with a resultan t lower LMP (p < 0.05) compared to gilts. None of the genotypes or sex es showed differences in chilling loss, but drip loss differed between genotypes (p < 0.05) and sexes (p < 0.001), with nn pigs having the l owest drip loss. The pH(1) values differed (p < 0.05) between genotype s, with NN the highest and nn the lowest. No differences in pH(24) wer e observed between genotypes. The pH(1) and pH(24) values did not diff er between sexes. Although the presence of the halothane gene positive ly affected growth rate, this increase in growth rate was largely due to undesirable fat deposition. Furthermore, the gene did not positivel y affect meat quality (pH(1)) or carcass quality (LMP). Therefore, the intentional use of the halothane gene is discouraged.