EFFECT OF SPACE ALLOWANCE ON BARROW PERFORMANCE TO 136 KILOGRAMS BODY-WEIGHT

Two experiments were conducted to examine the space requirements of ba rrows grown to 136 kg BW. In Exp. 1, barrows (initial BW 19.5 kg) were allowed .65, .84, or 1.02 m(2)/pig floor space in a fully slatted fac ility with 12 pigs/pen. In Exp. 2, conducted at three experiment stati ons in the north central region of the United States (Iowa, Indiana, N ebraska), barrows (initial BW 55.5 kg) were allowed .65, .93, or 1.20 m(2)/pig floor space in either partially or totally slatted facilities . In Exp. 1, there was a linear (P <.05) decrease in ADG for the first 29-d period with increasing space. Overall, ADG responded in a quadra tic (P = .09) manner to increasing space allocation (.841, .855, and . 824 kg/d for the .65, .84, and 1.02 m(2) treatments, respectively) wit h a linear (P = .06) decrease in gain:feed ratio (.322, .318, and .312 ). Space allocation had no effect (P >.10) on ADFI, last rib fat depth , or rate of lean gain. In Exp. 2, ADG improved linearly (P = .08) wit h increasing space (.836, .857 and .865 kg/d for the .65, .93, and 1.2 0 m(2) treatments, respectively), with a quadratic (P = .07) response in gain:feed ratio (.270, .265, and .268, respectively). There was no effect of spade allocation on uniformity of gain within a pen as measu red by coefficient of variation for pig weights within a pen at the ti me of first pig removal. The results of these experiments suggest that performance of barrows grown to 136 kg BW was maximized with .84 to 1 .0 m(2) of floor space per pig.