Factors influencing feed intake, growth performance, and behavior by Boer wethers with an automated feeding system

Effects of the number of Boer wethers (initial age and body weight of 0.78±0.014 yr and 34.4±0.90 kg, respectively) per automated feeder, allowing only one animal to consume feed at a given time, and length and time of feeder access on feed intake, growth performance, and behavior were determined during a 10-wk period. Treatments were 6 and 12 wethers per 6×6 m pen and feeder with continuous access (C-6 and C-12, respectively); 2 and 4 wethers per feeder with 8 h/day access during daytime (D-2 and D-4, respectively); and 4 and 8 wethers per feeder with 16 h/day access at night (N-4 and N-8, respectively). Therefore, maximal feeder occupancy time per wether was 4 h for C-6, D-2, and N-4 and 2 h for C-12, D-4, and N-8. Dry matter intake (DMI) was greater for continuous vs. restricted feeder access (P=0.001) and for night vs. daytime access (P=0.025) (2.04, 2.01, 1.45, 1.50, 1.92, and 1.76 kg/day; SE=0.133), and feeder occupancy time per wether tended (P=0.071) to be greater for continuous access (1.83, 1.55, 1.23, 1.34, 1.51, and 1.25 h/day for C-6, C-12, D-2, D-4, N-4, and N-8, respectively; SE=0.238). Rate of DMI was similar among treatments (P>0.15). There were effects of continuous vs. restricted (P=0.012) and D vs. N (P=0.051) access on average daily gain (ADG), as well as a tendency (P=0.078) for an interaction between time and length of restricted access (237, 252, 174, 207, 247, and 211 g for C-6, C-12, D-2, D-4, N-4, and N-8, respectively; SE=16.4). ADG:DMI tended (P=0.073) to be greater for night than for day access (P>0.05) (128, 130, 97, 117, 150, and 127 g/kg; SE=14.8), although residual feed intake (RFI) was greater (P=0.003) for continuous vs. restricted access and tended to be less for day vs. night access (P=0.119) and for 2 vs. 4 h/day of maximal occupancy time per wether (P=0.150) (121, 20, -63, -165, -16, and -14 for C-6, C-12, D-2, D-4, N-4, and N-8, respectively; SE = 53.4). In summary, continuous feeder access allowed high ADG, but resulted in relatively inefficient feed utilization as assessed by RFI. Restricting feeder access to daytime minimized DMI compared with continuous access, which was due to factors other than feeder occupancy time and rate of DMI; however, efficiency of feed utilization for daytime access based on RFI, particularly for D-4, was high relative to continuous access. In conclusion, restricting feeder access influenced feed intake, growth performance, and behavior, with results impacted by time of access.