Effects of Increasing Space Allowance By Removing a Pig or Gate Adjustment on Finishing Pig Growth Performance

A total of 256 pigs (PIC 327×1050; initially 55.9 kg) were used in a 71-d study to determine the effects of space allowance and pig removal on finishing pig performance. The 4 treatments included: 0.91m²/pig or 0.63m²/pig for the entire study and initially 0.63m²/pig with a gate adjusted or the heaviest pig removed to keep pigs above their predicted minimum space requirement (m²=0.0336*BW^0.66). Initially, there were 8 pigs/pen and 8 pens/treatment. From d 0 to 28, prior to any space adjustments, ADG was marginally greater (P=0.076) for pigs provided 0.91m² compared with those provided 0.63m². From d 28 to 71, ADG and ADFI decreased (P=0.001) when pigs were provided 0.63m² compared with pigs provided 0.91m². Pigs provided increased space by removing pigs had similar performance to those where gates were adjusted; however, pig removal resulted in lower ADFI than pigs allowed 0.91m² throughout the experiment. Overall, pigs allowed 0.91m² had increased (P=0.001) ADG compared with pigs allowed 0.63m² or either adjusted space treatment. Removing pigs or adjusting gating increased (P=0.001) ADG compared to those kept at 0.63m²; however, neither treatment had ADG similar to pigs allowed 0.91m². Pigs allowed 0.91m² had greater (P=0.001) ADFI compared with pigs allowed 0.63m² with adjusted space allowance pigs being intermediate. Feed efficiency was not affected throughout the experiment. In summary, either removing a pig or adjusting the gating as pigs reached the critical k-value influenced growth similarly. Results indicate the performance benefit from removing the heaviest pigs from the pen is primarily from increased space allowance. Pigs provided more space as they reached the space requirement had lower growth than unrestricted pigs indicating the minimum space prediction equation (m²=0.0336*BW^0.66) doesn’t fully explain pen space effects on pig performance.

Item1	0.91m2	0.63m2	Gate adjustment	Pig removal	SEM	Probability, P<
BW, kg
d 0	55.9	56.0	55.9	55.6	0.15	0.361
d 28	84.0x	82.3y	82.6y	82.8y	0.47	0.081
d 71	132.4a	126.2c	130.3b	125.2c	0.71	0.001
d 0 to 28
ADG, kg	1.00x	0.94y	0.95y	0.97xy	0.015	0.076
ADFI, kg	2.39	2.28	2.35	2.37	0.036	0.200
d 28 to 71
ADG, kg	1.01a	0.92b	0.98a	0.98a	0.013	0.001
ADFI, kg	3.01a	2.77c	2.97ab	2.89b	0.035	0.001
d 0 to 71
ADG, kg	1.00a	0.93c	0.97b	0.98b	0.009	0.001
ADFI, kg	2.76a	2.58c	2.73ab	2.66b	0.029	0.001
1Means within a row differ: abcP<0.05, xyzP<0.10.