Abstract

Correlated responses in reproductive performance to five generations of divergent selection for daily food 
intake (DFI), lean food conversion (LFC), lean growth rate on ad-libitumfeeding (LGA), and lean growth rate on 
scale feeding (LGS) were studied. Litter traits were measured on 1220 selected Large White gilts. Litter birth 
weights were reduced (-2.8kg) in the low DFI and high LFC lines. The response for litter birth weighl in LGS 
was greater than in LGA (3.0 vs -0.1). Relationships between litter size, litter weights and piglet weights at birth 
and weaning were essentially linear. An extra piglet at birth and weaning corresponded to an increase of 1.0 
kg and 6.9 kg in litter weights and a decrease of 0.03 kg and 0.19 kg in piglet weights. Heritabilities for litter 
size, weight and piglet weight at birth (0.06, 0.11 and 0.16) were similar to those at weaning. Common 
environmental effects on piglet weights (0.38 and 0.45) were higher than heritabilities.
 

J. C Kerr, N. D Cameron

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 17. Genetics and breeding of dairy and beef cattle, swine and horses, , 339–342, 1994