Evaluation of Station Testing of Pigs

Abstract

Variances and covariances were estimated by iteration on a multiple trait extension of Henderson's method 4 for slaughter traits from the Swedish progeny/sib test stations. Standard errors of genetic parameters were estimated through a simulation study, and the efficiency of the multiple trait analysis was compared with the efficiency of the corresponding single trait analysis. The multiple trait analysis of variance usually gave smaller standard errors for the genetic correlations than the single trait analysis. It was possible to explain 45% of the variance in relative efficiency (measured as simulated standard error of multiple trait analysis divided by simulated standard error for single trait analysis) by the simple regression on the product of the absolute difference between the heritabilities and the difference between genetic and error correlation. The greater this product, the greater the gain in relative efficiency obtained by multiple trait analysis. Heritabilities were for meat colour 0.35±0.04 and 0.26±0.07, for pH₂ in m. longissimus dorsi 0.27±0.04 and 0.30±0.04, for pH₂ in m. quadriceps femoris 0.22±0.05 and 0.18±0.07, and for pH₂ in m. biceps femoris 0.25±0.05 and 0.21±0.06 for the Landrace and Yorkshire respectively. Meat colour showed unfavourable genetic correlations to both lean percentage and daily gain, and there was some evidence that they are changing in more unfavourable direction with time. A revision of the index to prevent further deterioration in meat quality traits is recommended.

Key Words:

• variance components
• antagonistic traits
• simulation
• standard error