Proportional yields and processing of pork derived from different halothane hyperthermia pig genotypes

[摘要] ENGLISH ABSTRACT: The carcass and meat quality characteristics of three halothane genotypes in pigs were evaluated.Sixty crossbred Landrace x Large White pigs (NN = 25, Nn = 19, nn = 16) of ± 86 kg live weightwere slaughtered, the carcasses chilled for 24 h at 2°C, certain carcass and meat quality traitsdetermined and the shoulder and leg cuts deboned and devided into primal cuts. Least squares (LS)means for dressing percentage of the Nn genotypes was higher (P < 0.05) than that of the NN andnn genotypes. LS means for carcass length was highest (P < 0.05) for carcasses derived from the nngenotype. The LS means calculated for several measurements on the split carcasses (midline fatmeasurements) and cross sections between the 2nd and 3rd last thoracic vertebrae relating to fatdepositioning (45 mm from the midline) and lean depositioning (eye muscle width, depth and area)provided significant evidence that the nn genotype yielded leaner carcasses than Nn and NNgenotypes. Fitting prediction equations to some of the these measurements to calculate LS meansfor predicted lean yield confirmed that nn genotypes yielded carcasses with less fat and more lean.Further dissecting of selected cuts (shoulders and legs) also showed that the LS means for bone, fatand lean yield from nn genotypes were more desired than those from the other two genotypes, withprobabilities varying from P > 0.05 to P -< 0.001. It was also demonstrated that the LS means of allsubprimal cuts from the legs (topside, silverside, thickflank and rump) expressed as a percentage ofcold carcass weight were higher for carcasses originating from the nn genotype (P < 0.05). Thiscould be ascribed to the higher LS means for leg weight (P < 0.05) originating from the nngenotype. However, when meat quality traits were compared the shortfall of the nn genotypesbecame evident. LS means for pILs (P < 0.001), pH24 (P < 0.05), drip loss (P < 0.001) andreflectance values (P < 0.05) differed and were inferior for this genotype.The backs and legs were used to prepare cured, smoked bacon and canned hams. Comparison of LSmeans revealed the following: initial gain in pumped weight was significantly higher (P < 0.001)for the NN and Nn genotypes compared to the nn genotypes. Similarly, the total gain in bacon yield(finished product yield) was the highest for the Nn (11.5%) and NN genotypes (1O.0%),significantly higher (P < 0.05) than the bacon produced from the backs of the nn genotypes (3.4%).Differences between sexes were not significant. Canned hams (without added phosphate) producedfrom the NN genotypes had a significantly (P < 0.001) lower percentage cooking loss (27.92%)compared to that of the Nn (30.12%) and nn genotypes (31.14%), which did not differ. Addition ofphosphates (0.3% on final product) had a similar response, with the hams produced from the NNgenotype having 13.75% cooking loss, significantly lower (P < 0.001) than the Nn (16.87%) and nngenotypes (17.73%). Results for the two types of fresh sausage manufactured from the meat of the different genotypes(with rusk, without rusk) indicated that for the sausage without rusk that the NN genotypes (15.7%)had lower total moisture losses (P < 0.05) compared to the nn genotypes (18.9%), with Nnintermediate (17.4%). The treatment with rusk addition did not differ significantly betweengenotypes (NN = 12.6%, Nn = 13.0, nn = 14.2%), indicating that some of the disadvantages may beovercome by processing technique. Taste panel evaluation of the fresh sausage made without ruskindicated no differences between genotypes when evaluated for juiciness. In an emulsion typesausage the smoking and cooking losses during manufacturing of the product indicated that thesausage manufactured from the meat of the nn genotype (12.47%) had significantly (P < 0.05)higher losses than that from the Nn genotype (1l.31 %), with NN genotype intermediate (12.35%).The results from this investigation suggest that the presence of the halothane gene is associated withdecreased fresh meat and processing properties (lower water holding capacity, reflected by yield ortotal loss and higher reflectance values) in certain products. This leads to inferior quality in finishedproducts as well as deminished financial returns for processors.

[发布机构] Stellenbosch University