more useful (Hoque et al., 2009). Residual feed intake
(RFI) is defined as the difference between the observed
feed intake and the expected feed intake for a given
production (i.e., growth or meat production in pigs)
and is a commonly used measure of feed efficiency.
Therefore, selection for reduced RFI could improve the
efficiency of energy use without reducing the feed intake
capacity that is required for production (Kennedy et al.,
1993). Recent studies showed that pigs with lower RFI
had better feed conversion efficiency and meat quality
(Gilbert et al., 2007). In ruminants, selection for reduced
RFI has also provided decreased environmental impact
in sheep (Muro-Reyes et al., 2011) and cattle (Carberry
et al., 2012). Food conversion ratio (FCR) is currently
included in the selection index for the Danish pig breeds.