Effects of selection for decreased residual feed intake on composition and quality of fresh pork1

Abstract

The objectives of this study were to determine the extent to which selection for decreased residual feed intake (RFI) affects pork composition and quality. Pigs from the fifth generation of selection for decreased RFI (select) and a randomly selected line (control) were utilized. Two experiments were conducted. In Exp. 1, barrows (22.6 ± 3.9 kg) from select and control lines were paired based on age and BW. The test was conducted in 8 replicates of pairs for the test period of 6 wk. Calpastatin activity and myosin isoforms profile were determined on samples from the LM. Control barrows were heavier (59.1 vs. 55.0 kg; P < 0.01) at the end of the test period. Calpastatin activity was greater (P < 0.01) in LM of select barrows than control barrows. In Exp. 2, composition and quality of gilts (114 kg) from control and select lines were determined. The model included fixed effects of line, slaughter date, melanocortin-4 receptor (MC4R) genotype, barn group, line × slaughter date, genotype × line interactions, a covariate of off-test BW, and sire, pen, and litter fitted as random effects. The select line (n = 80) had 0.043 kg less (P < 0.05) RFI per day than the control line (n = 89). Loin quality and composition were determined at 2 d postmortem. Desmin degradation was measured at 2 and 7 d postmortem. Purge, cook loss, sensory traits, and star probe texture were measured at 7 to 10 d postmortem on cooked chops. Residual correlations between RFI and composition and quality traits were calculated. Compared with the control line, carcasses from the select line tended to have less (P = 0.09) backfat, greater (P < 0.05) loin depth, and greater (P < 0.05) fat free lean. Loin chops from the select line had less (P< 0.01) intramuscular lipid content than loin chops from control line. Significant residual correlations between RFI and both tenderness (r = 0.24, P < 0.01) and star probe (r = −0.26, P < 0.01) were identified. Selection for decreased RFI has the potential to improve carcass composition with few effects on pH and water-holding capacity. However, decreased RFI could negatively affect tenderness and texture because of decreased lipid content and decreased postmortem protein degradation. ABSTRACT:The objectives of this study were to determine the effect of selection for improved residual feed intake on behavior, activity, and lesion scores in gilts in their home pen. A total of 192 gilts were used, 96 from a line that had been selected for decreased residual feed intake over 5 generations (LRFI) and 96 from a randomly bred control line. Gilts were housed in 12 pens (16 gilts/pen; 0.82 m 2 /gilt) containing 8 gilts from each line in a conventional grow-finish unit. Twelve hours of video footage were collected on the day of placement and then every 4 wk for 3 more observational periods. Video was scored using a 10-min instantaneous scan sampling technique for 4 postures (standing, lying, sitting, and locomotion) and 1 behavior (at drinker). Categories of active (standing, locomotion, and at drinker) and inact...

Liver and skeletal muscle mitochondria proteomes are altered in pigs divergently selected for residual feed intake1,2

“…We have reported the unique protein profile and PTM differences in comparisons of pigs that were genetically and phenotypically divergent in feed efficiency during the growing period. The differences in growth performance reported in these comparisons are consistent with previously published results from these same lines of pigs (Cai et al, 2008;Grubbs et al, 2013b;Harris et al, 2012;Smith et al, 2011) and another similar swine RFI genetic selection project (Barea et al, 2010;Lefaucheur et al, 2011). Phenotypic differences in RFI without genetic selection for RFI have also been reported in cattle Table 5.…”

“…Before the fifth generation, the high RFI line was a randomly selected control group, meaning genetic selection for high RFI lags 5 generations behind the selection for low RFI in the low RFI line. As with previously published reports in genetic selection for RFI in pigs, there was no difference in the final BW between the lines (Lefaucheur et al, 2011;Smith et al, 2011). Data from this study and previously published reports Harris et al, 2012) on these same lines of pigs indicate that genetic selection for RFI may provide a good model for understanding molecular differences in RFI when compared to single phenotypic comparisons.…”

“…They would also like to thank the Dekkers group, in particular Dr. Jennifer Young, for management, data collection, and RFI calculations associated with the RFI selection lines at Iowa State University. RFI (Grubbs et al, 2013b;Smith et al, 2011) provides insight into cellular processes that govern feed efficiency. Therefore, the overall objective of this paper was to determine the extent to which the mitochondria protein profile of skeletal muscle and liver relate to feed efficiency in pigs divergently selected for RFI.…”

Evidence of decreased muscle protein turnover in gilts selected for low residual feed intake1

“…Across muscles, μ-and m-calpain activities tended to be lesser (P = 0.10 and 0.09, respectively) in muscle from the more efficient low RFI pigs compared with high RFI pigs (Table 2). Furthermore, total calpastatin activity was greater (P < 0.05) in muscle from low RFI pigs, which is consistent with previous findings in younger pigs (Smith et al, 2011). The difference in total calpastatin activity can be attributed primarily to differences in calpastatin II activity (P = 0.01), given that activity of calpastatin I was not different between lines (P = 0.79).…”

“…In the Iowa State University RFI Yorkshire pig selection project, pigs in the low RFI line are more efficient and tend to have less carcass fat, greater carcass lean, and lesser ADG compared with control and high RFI lines (Cai et al, 2008;Smith et al, 2011;. Boddicker et al (2011a,b) reported a trend for increased protein and decreased fat composition in carcasses from Yorkshire pigs selected for low RFI compared with the control line.…”