Abstract
The objective was to determine the relationship between feed intake levels and patterns, and growth performance and body composition of barrows and gilts using automatic feed intake recording equipment (F.I.R.E.). This system records the time of visits to the feeder and the duration and size of meals for individual animals housed in groups. Ninety-six crossbred pigs were grown from $33.4{\pm}0.51$ to $109.7{\pm}1.39kg$ live weight over a 13-week period. Eight mixed-sex groups of 12 pigs were used and 4 dietary treatments were compared giving 2 pens per treatment. The dietary treatments consisted of corn-soybean meal diets with differing protein levels which ranged from 14.7% to 19% between 30 to 55 kg, from 13.3% to 16.9% between 56 and 85 kg, and from 12.3% to 16.8% for the remainder of the study. Animals were ultrasonically scanned to measure loin-eye area and backfat thickness to estimate carcass fat-free lean content at the beginning and end of the study. Barrows had higher daily feed intake than gilts (2.67 vs. 2.46 kg resp. p<0.05) which was the result of a longer feeder occupation time per visit (4.77 vs. 4.54 min, resp. p<0.05), higher feed consumption rates (30.4 vs. 29.0 g/min, resp. p<0.05), and higher feed intakes per visit (136.9 vs. 126.8 g, resp. p<0.01). Gilts had less backfat and greater loin-eye area than barrows (p<0.05). Diet had no significant effect on growth performance and had limited impact on feeding patterns. Body weight showed high correlations with ADG (r=0.74), feed intake per visit (r=0.51) and feed consumption rate (r=0.69). Positive correlation were also found between daily feed intake and feed intake per visit (r=0.45), feeder occupation time per day (r=0.56), and feed consumption rate (r=0.55), and between daily feed intake and backfat thickness (r=0.32) and feed consumption rate and loin-eye area (r=0.32). There were negative correlations between number of feeder visit per day and daily feed intake (r=-0.54), and between feed intake per visit and number of feeder visits per day (r=-0.43). However, correlations between feed intake traits and carcass traits were generally low. Visits to the feeder were greatest during the morning (0700 to 1100 h) and lowest during the evening and nighttime. These results highlight limited variation among the sexes in feeding patterns and suggest important relationships between feeding behavior and feed intake.