EFFECT OF INDIVIDUAL HOUSING ON THE FEEDING-BEHAVIOR OF PREVIOUSLY GROUP-HOUSED GROWING PIGS

The feeding behaviour of individually housed growing pigs differs sign ificantly from that of group housed animals, with individual penning r esulting in shorter, more frequent visits to the feeding trough (De Ha er and Merks, 1992. Anim. Prod., 54: 95-104). Substituting group housi ng by a single housing environment was therefore expected to increase substantially the number of visits to the feeding trough. Three groups of ten cross-bred entire male pigs (initial live-weight 29.3 +/- 0.6 kg; mean +/- SE) were housed for 14 days (Period 1) with ad libitum ac cess to one computerized single-space feeder per group. Four pigs were chosen from each group; two pigs showing a high feeding frequency (It pigs: 18.9 +/- 2.0 visits day(-1); mean +/- SE; n = 6) and two pigs s howing a low feeding frequency (L pigs: 9.5 +/- 0.8 visits day(-1); me an +/- s.e.; n = 6). The L pigs had a higher feed intake per visit (13 7 vs 82 g per visit; SED = 8; P < 0.001), acid a lower daily feed inta ke (1246 vs 1477 g day(-1); SED = 84; P < 0.05) than H pigs, On Day 15 , H and L pigs were moved to individual pens identical to the group pe ns for a period of 14 days (Period 2). This individual housing resulte d in only a small increase in the frequency of feeder visits (2.8 +/- 0.8 visits day(-1)), irrespective of the feeding frequency displayed b y the pigs during Period 1. The relatively small increase in number of daily feeder visits resulted in a significant increase (P < 0.05) in daily feed intake, leading to no differences between pigs in daily fee d intake once individually penned, Pigs showing a low number of daily feeder visits when group housed may have been constrained in terms of daily feed intake as a result of the displayed feeding pattern. In add ition, the feeding pattern of growing pigs may be less flexible than e xpected, and pigs, which have been constrained in their food intake, w ill make only small modifications to their feeding pattern, sufficient to compensate for the previous constraint. It is likely that growing pigs will adhere to a feeding pattern that has provided them with suff icient food in the past, even when a change in the environment allows for more extreme modifications to occur.