The effect of sire line on the feeding patterns of grow-finish pigs

Forty-eight growing-finishing pigs were used in a split-plot design with a 2 × 2 factorial arrangement of treatments to investigate the effect of sire line and sex (castrates and gilts) on feeding patterns. Sire line A was of Pietrain ancestry and sire line B was a synthetic line that included Large White, Landrace, Duroc, and Pietrain. Sires from line A (n = 8) and line B (n = 9) were mated with PIC Camborough 22 females. Growth performance and feeding patterns of the progeny were measured from 40.2 ± 2.04 to 120.0 ± 2.85 kg body weight (BW). Pigs were housed in groups of eight, with two pigs from each line × sex subclass in each pen, at a floor space allowance of 0.9 m² per pig. Feeding patterns were monitored by a computerized feed intake recording equipment (FIRE) system. Line B progeny had higher growth rates (1036 versus 956 g per day, S.E. = 15, P < 0.01), higher feed intakes (2657 versus 2470 g per day, S.E. = 61.2, P < 0.05), but similar gain:feed ratios, as compared to the progeny of line A. Line B pigs tended to have smaller loin-eye depths (P < 0.10), and had greater lean growth rates (P < 0.01) than line A pigs. Line B pigs, compared to line A pigs, had a greater feed intake per visit (207 versus 172 g, S.E. = 9.9, P < 0.05), and a higher feed consumption rate (36.7 versus 28.7 g/min, S.E. = 2.41, P < 0.05). Line B pigs tended to have lower feeder occupation times per day than line A pigs (P < 0.10). There were no differences between the two sire lines for number of feeder visits or feeder occupation time per visit (P > 0.10). Castrates had higher growth rates (P < 0.01) and feed intakes (P < 0.001), lower gain:feed ratios (P < 0.01), but similar (P > 0.05) feeding patterns compared to gilts. Feeding patterns showed significant changes with increasing BW: number of feeder visits and feeder occupation time per visit, and per day decreased linearly, while feed intake per visit and feed consumption rate increased linearly with increasing pig BW. The rates of change in a number of feeding pattern traits differed (P < 0.05) between the two genetic lines. The results of this study highlight the influence of genetic ancestry and, particularly, BW on growth performance and feeding patterns in growing-finishing pigs.