Effects of increasing space allowance by removing a pig or gate adjustment on finishing pig growth performance

A total of 256 pigs (initially 55.9 ± 4.88 kg) were used in a 71-d study to determine the effects of increasing space allowance and pig removal on pig growth performance. Pens of pigs were blocked by body weight (BW) and allotted to 1 of 4 space allowance treatments, initially with 8 pigs per pen and 8 pens per treatment. First 2 treatments included pens with 0.91 m2 per pig or 0.63 m2 per pig for the entire study; two additional treatments initially provided 0.63 m2 per pig, but either a gate was adjusted on days 28, 45, and 62 or the heaviest pig in the pen was removed from the pen on days 28 and 45 to provide more space and keep pigs in accordance with their predicted minimum space requirement [(m2) = 0.0336 × (BW, kg)0.67]. From days 0 to 14 (56 to 69 kg), there was no effect of stocking density observed for average daily gain (ADG), average daily feed intake (ADFI), and gain:feed (G:F). From days 14 to 28 (69 to 83 kg), pigs provided 0.91 m2 had increased (P < 0.05) ADG and G:F compared with those allowed 0.63 m2. Pigs provided 0.91 m2 were marginally heavier (P = 0.081) on day 28 and had greater ADFI (P = 0.025) during days 28 to 45 than those provided 0.63 m2 or those that had the heaviest pig removed. From days 45 to 62 (98 to 116 kg), pigs provided 0.91 m2 were heavier (P < 0.01) than all others, wheras pigs provided 0.63 m2 had reduced ADFI compared with other treatments. From days 62 to 71 (116 to 124 kg), pigs provided 0.91 m2 and those with space adjustment treatments had greater (P < 0.05) ADG and ADFI than those provided 0.63 m2. Overall (56 to 124 kg), pigs provided 0.91 m2 had increased (P = 0.001) ADG compared with those allowed 0.63 m2 with pigs provided space adjustments intermediate. In summary, pigs with 0.91 m2 grew faster and consumed more feed than pigs restricted in space. As pigs reached the critical k value, gate adjustments and pig removals affected growth similarly. As pigs grew to the predicted space requirement and were subsequently allowed more space, performance was greater than those provided 0.63 m2 but less than those allowed 0.91 m2. It appears that the industry accepted critical k value, 0.0336, may not be adequate for optimal pig performance across multiple BW ranges.