Influence of sex and breed on the precision of the official Swedish pig carcass grading.
1995
Andersson A. | Hansson I. | Lundstroem K. | Karlsson A.
The official Swedish pig carcass grading system predicts the content of lean meat by means of the Hennessy Grading Probe (HGP). In 1984 when the system was introduced, most of the slaughtered pigs were two-breed crosses. Since then the use of three-breed crosses has increased markedly, while the prediction equation has remained unaltered. This has focused interest on the precision of the prevailing grading system and how breed and sex affect the prediction. In this study, 317 carcasses were sampled at four separate commercial abattoirs. The carcasses were either two-breed crosses (Swedish Landrace x Swedish Yorkshire (L x Y) or three-breed crosses between (L x Y, x L, Y dams and either Hampshire or Duroc terminal sires. Three sexes were represented, castrates, gilts and entire males. Measurements of fat and muscle thickness were recorded on the slaughter line at grading with HGP (approx. 45 min post mortem). Before cutting of the cold carcasses, they were again probed with HGP and the fat and muscle thicknesses were recorded. The actual lean meat percentage in the carcasses was determined according to the method used in the Swedish pig progeny testing system. This method uses a combination of complete and partial dissections where the partial dissection includes jointing and defatting of the loin and ham. The results show that the prevailing grading system overestimated the lean meat content in fat carcasses, while lean carcasses were underestimated. Carcasses from Hampshire crosses and entire male pigs were generally more underestimated than were carcasses from other breeds and sexes. This was mostly attributable to larger and leaner hams, respectively. Formulation of a new prediction equation based on the present study reduced the prediction bias considerably. Moreover, HGP measurements on cold carcasses were shown to be just as good estimators of lean meat content as were HGP measurements on warm carcasses.
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