Additive and heterotic breed effects in the genetic evaluation of pig sire breeds

Abstract

The data sets consisted of field performance data from 54 848 purebred and 16 175 crossbred animals (Czech data set, CZ) and 16 610 purebred and 9 228 crossbred animals (Slovak data set, SK). Animals from the following breeds were included: Duroc, Hampshire, Piétrain, sire line of Large White (CZ) or Yorkshire (SK), Czech Meat pig (CZ) or Slovak Meat pig (SK), Belgian Landrace (SK). Two-trait animal models were calculated for average daily gain from birth to the end of the field test (ADG) and lean meat content (LM, only in CZ) or backfat thickness (BF, only in SK). The models included additive breed and breed heterotic effects. Piétrain was the breed with the highest LM and the lowest BF. The additive genetic breed effect was about 1·5% LM (CZ) in comparison with Large White or −0·4 mm BF (SK) in comparison to Yorkshire. The sire line of Large White (CZ) or the Yorkshire breed (SK) clearly exceeded all the remaining sire breeds in ADG (on average by 30 to 50 g/day). There was a clear tendency to negative heterosis in LM in all crossbred combinations (CZ). In BF, heterotic effects between −0·2 mm and +0·3 mm were estimated, mostly not being significant (SK). The estimates of the heterotic effects for ADG were positive throughout. Higher values up to 40 g/day (7%) were observed in the Czech data set. Though heterotic breed effects are of some importance especially for ADG, their inclusion in the equations for breeding value estimation will have only a minor impact on the predicted breeding values.