Effects of the number of yearling Boer crossbred wethers per automated feeding system unit on feed intake, feeding behavior and growth performance

Thirty-six growing Boer × Spanish wethers (initial BW of 30 ± 0.7 kg) were used in an 82-day experiment to determine effects of the number of animals per automated feeding system (NPF; 6, 8, 10 and 12), allowing consumption by only one animal at a given time, on intake of a 50% concentrate pelletized diet (9.2 MJ/kg ME, DM basis), feeding behavior and growth performance. During the entire experiment DM intake (1454, 1513, 1596 and 1374 g/day) and BW gain (156, 167, 181 and 136 g/day for 6, 8, 10 and 12 NPF, respectively) were affected by NPF quadratically (P < 0.05), although gain efficiency (ADG:DM intake) was similar among NPF. The number of feeder visits (17.5, 17.1, 17.9 and 18.7) and meals (8.9, 9.0, 9.3 and 8.9) were similar among NPF, although feeder occupancy per day (97.8, 73.2, 83.0 and 71.7 min), visit (5.8, 4.4, 5.0 and 3.8 min) and meal (11.2, 8.2, 9.2 and 8.1 min for 6, 8, 10 and 12 NPF, respectively) decreased linearly with increasing NPF (P < 0.05). The rate of DM consumption relative to feeder occupancy time plateaued as NPF increased to 8 (linear and quadratic changes, P < 0.05; 14.6, 24.9, 21.5 and 23.1 g/min for 6, 8, 10 and 12 NPF, respectively). In conclusion, with these diet and animal characteristics, 8 or 10 wethers per automated feeder appear appropriate for achieving unrestricted growth performance.