The Thai Journal of Veterinary Medicine


Residual feed intake (RFI) is the difference between the actual feed intake (AFI) and the expected feed intake (EFI). RFI has become an increasingly important trait and is being considered as a more practical approach to evaluate feed efficiency (FE) in livestock. Data from 479 purebred Landrace pigs involved in a performance test were used in this study. Pigs were housed in an individual pen and fed ad libitum the same formula diet consisting of 2,950 kcal/kg of ME and 16% crude protein. Clean water was available to the pigs at all time. Pigs were weighed at the beginning and end of the test, backfat thickness (BF) was measured at the end of the test and feed intake was recorded. EFI was predicted using the model that included sex and common litter effects as well as covariates of average daily gain (ADG) and BF. Variance components were estimated using an animal model by the restricted maximum likelihood (REML) method. The heritability estimate for RFI was low (0.16 ± 0.10), while the estimates for FE and ADG were moderate (0.33 ± 0.15 and 0.38 ± 0.17, respectively). The moderate favorable genetic correlation was estimated between RFI and FE (-0.55 ± 0.27). The genetic correlations between RFI and ADG, and FE and ADG were not significantly different from zero (0.02 ± 0.38 and 0.15 ± 0.31 respectively). Considering heritabilities of FE and RFI, the results indicated that selections for improving FE were possible. Genetic correlation indicated that selection for reduced RFI would increase FE without adversely affecting ADG.

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