Responses in residual feed intake in lines of Large White pigs selected for growth rate on restricted feeding (measured on ad libitum individual feeding)

Abstract

Residual feed intake (RFI) represents the deviation of the actual ad libitum food consumption of each animal from that predicted from combination of growth rate, backfat and metabolic body weight measurements. After 4 years of divergent selection of pigs in lines for either high or low postweaning growth rate on restricted feeding, the high line exhibited a significant reduction in RFI relative to the low line. This indicated, to some extents, a lower energy requirement for maintenance in the high than in the low line, possibly because of reduced physical activity of the animals. Estimates of genetical parameters showed that RFI was moderately heritable and those genetic correlations of RFI with carcass backfat and food conversion ratio were moderate to highly positive.

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

“…Johnson et al (1999) also estimated strong genetic correlations for BF with measures of RFI not adjusted for BF (0.67 for RFI1 and RFI2). Similar results were reported by Nguyen et al (2005), who noted that selection for low RFI would improve carcass leanness in Large White pigs. Negative genetic correlations were found between LEA and all measures of RFI, which are in agreement with the estimates reported by Johnson et al (1999), who also found negative genetic correlations between LEA and four measures of RFI (ranged from −0.31 to −0.51).…”

Consequences of divergent selection for residual feed intake in pigs on muscle energy metabolism and meat quality

“…Consequently, lean meat content was increased in the RFI − compared with RFI + line pigs as previously reported at an earlier stage of the selection experiment . A decrease in back-fat and an increased LMC without any change in ADG have also been reported in other selection experiments for low RFI in growing pigs (Cai et al, 2008;Johnson, Chewning, & Nugent, 1999;Mrode & Kennedy, 1993;Nguyen, McPhee, & Wade, 2005).…”

Composition and quality characteristics of carcasses from pigs divergently selected for residual feed intake on high- or low-energy diets1

“…RFI is a moderately heritable trait (Arthur et al, 2001;Nguyen et al, 2005;Hoque et al, 2009) that can be calculated as the difference in observed feed intake and expected feed intake given an animal's growth requirement for production and maintenance of body weight . It is an animal's residual from the regression line where observed equals expected that is its RFI index ( Figure 1).…”

“…Animals with a low RFI (LRFI) indexes consume less feed and are generally more efficient than high RFI (HRFI) animals. RFI is a moderately heritable trait (Arthur et al, 2001;Nguyen et al, 2005;Hoque et al, 2009), that can be used as a genetic selection tool. The Institut National de la Recherche Agronomique (INRA) and Iowa State University (ISU), have established multi-generational RFI swine selection projects.…”

“…Residual feed intake (RFI) is a moderately heritable trait (Arthur et al, 2001;Nguyen et al, 2005;Hoque et al, 2009) which can be used to select for feed efficiency;…”