Selection for growth rate in pigs on restricted feeding. Genetic parameters and responses in growth rate and body composition traits for group housed ad libitum fed pigs

Abstract

Residual Feed Intake (RFI) represents the deviation of the actual ad libitum food consumption from that predicted on the basis of growth rate alone, or combined with backfat. After four years of selection of lines for high and low post weaning growth rate on restricted feeding, the high line
exhibited a significant reduction in RFI relative to the low line. This indicated a lower energy requirement for maintenance in the high than the low line, possibly due to reduced physical activity. Estimates of genetic parameters showed that RFI was moderately heritable. Genetic correlations of RFI with backfat and food conversion ratio were moderately to highly positive, suggesting that selection for low RFI would improve carcass lean content and efficiency of food utilisation.