The value of shape as a predictor of carcass composition in pigs from different breeding companies

Abstract

ABSTRACTCarcass data for a total of 1385 pigs from years 3 to 6 of the Meat and Livestock Commission's Commercial Pig Evaluation were used to examine the value of different shape assessments as predictors of carcass composition, when used in addition to carcass weight and fat thickness over the m. longissimus at the head of the last rib (P2). The sample comprised pigs from 13 breeding companies and a purebred Large White control.The standard deviation of carcass lean proportion at equal weight and P2 was 24·5 g/kg. The addition of carcass length or visual conformation assessments (five-point scales) provided a small improvement in precision (minimum residual standard deviation = 24·2 g/kg). This improvement was associated with a reduction in the variation of lean to bone ratio.The addition of an effect for breeding company to weight and P2 improved the precision substantially (residual standard deviation = 23·1 g/kg). The improvement was due mainly to the identification of differences in carcass fat content, there being a range of 30g/kg in carcass fat content between companies at equal weight and P2.There was a further small improvement in precision from the addition of conformation assessments to weight, P2 and company (minimum residual standard deviation = 22·9 g/kg).The study confirms earlier results which indicate that shape assessments are of limited value as predictors in the British pig population, due mainly to limited variation in lean to bone ratio. It also indicates that significant variation exists between companies in fat content at equal P2 and weight which is not explained by shape assessments.