Genetic parameters for measures of residual feed intake and growth traits in seven generations of Duroc pigs

Abstract

Residual feed intake (RFI) represents the deviation of the actual feed consumption of an animal from that predicted from combination of growth traits. Data on 1642 Duroc (380 boars, 868 gilts, and 394 barrows) pigs in seven generations were used to estimate genetic parameters for measures of RFI, daily feed intake (FI), average daily gain (ADG), backfat (BF), and loin eye area (LEA). Four measures of RFI were estimated from models that included initial test age and weight, and ADG (RFI1); initial test age and weight, ADG, and BF (RFI2); initial test age and weight, ADG and LEA (RFI3); and initial test age and weight, ADG, BF, and LEA (RFI4). Genetic parameters were estimated using an animal model by the REML method. Heritability estimates for measures of RFI were moderate (ranged from 0.22 to 0.38). The corresponding estimates for FI, ADG, and LEA were also moderate (ranging from 0.45 to 0.49), while the estimate for BF was high (0.72). Genetic correlations of FI with ADG (0.84) and BF (0.67) were high. LEA negatively correlated with FI (− 0.42), ADG (− 0.11) and BF (− 0.44). Genetic correlations of BF with measures of RFI were higher when BF was not included in the estimation of RFI (0.77 with RFI1 and 0.76 with RFI3 vs. 0.11 with RFI2 and 0.07 with RFI4). Genetic correlations of LEA with measures of RFI were all negative (ranged from − 0.30 to − 0.60). Selection for ADG, LEA, BF, and intramuscular fat has resulted in small but favourable genetic changes in measures of RFI. Phenotypic correlations between measures of RFI were zero, and genetic correlations between them were low (0.17 to 0.23). FI was strongly correlated with all the measures of RFI, both genetically (ranged from 0.56 to 0.77) and phenotypically (ranged from 0.56 to 0.66). The results suggested that selection against RFI may cause a reduction in FI. BF should also decrease, and LEA should increase. The amount of change in BF or LEA would vary depending on whether RFI was adjusted for BF.