Deriving genomic breeding values for residual feed intake from covariance functions of random regression models

Abstract Text: Random regression models were used to estimate covariance functions between cumulated feed intake (CFI) and body weight (BW) in 8424 Danish Duroc pigs. Random regressions on second order Legendre polynomials of age were used to describe genetic and permanent environmental curves in BW and CFI. Based on covariance functions, residual feed intake (RFI) was defined and derived as the conditional genetic variance in feed intake given mid-test breeding value for BW and rate of gain. The heritability of RFI over the entire period was 0.36, but more interestingly, the genetic variance of RFI was 6% of the genetic variance in feed intake, revealing that a minor component of feed intake was genetically independent of maintenance and growth. In conclusion, the approach derived herein led to a consistent definition of RFI, where genomic breeding values were easily obtained.

Keywords:

Pigs

Feed efficiency

Genomic prediction