Effect of Floor Space Allowances on Growth Performance of Finishing Pigs Marketed at 138 Kilograms

Floor space allowances for market pigs were determined 10 to 20 years ago using pigs that were marketed at a body weight of about 113 kg or less. Currently, pigs are regularly marketed at over 128 kg. In light of this increased weight, we conducted two experiments to determine if current floor space allowances apply to pigs marketed at greater than 128 kg. In Exp. 1 conducted at 5 university research stations, we evaluated the growth performance, salivary cortisol concentrations, and lesion scores of pigs weighing between 27 and 138 kg provided 0.71, 0.80, 0.89, 0.98, or 1.07 m²/pig of floor space. Within station, group size (range = 6 to 19 pigs) remained constant across floor space treatments but pen size was altered to achieve the desired space allocations. There were 14 replicate pens for each treatment and pen groups remained intact until the end of the experiment. Overall, increasing floor space allowance increased final BW (linear, P = 0.04) and tended (linear, P < 0.06) to increase ADG and ADFI. There were no improvements in final BW or ADG beyond 0.89 m²/pig. Neither gain:feed, salivary cortisol concentrations nor lesion scores were affected by floor space allowances. Floor space needs of pigs nearing market weight was the focus of Exp. 2 conducted at 4 research stations. Pigs weighing about 130 kg were assigned to pens that provided the same space allowances as Exp. 1. Group size ranged from 4 to 11 pigs per pen but was constant across floor space treatments within station. The study lasted 2 wk and there were 8 replicate pens per treatment. As floor space allowance increased, ADG (linear, P < 0.01), ADFI (quadratic, P < 0.05), and final BW (linear, P < 0.01) increased (Table 1). Based on the results of these two experiments, pigs marketed at about 138 kg require at least 0.89 m²/pig to support optimal growth performance. However, heavier pigs (about 148 kg) at the end of the finishing period require 0.98 m²/pig.

Table 1. Effect of floor space allowance for pigs weighing 130 kg (Exp. 2)
	Floor space allowances (m2/pig)
Trait	0.71	0.80	0.89	0.98	1.07	SE
ADG1, kg	0.86	0.95	0.95	1.10	1.06	0.04
ADFI2, kg	3.03	3.26	3.22	3.49	3.25	0.06
Final BW1, kg	145.6	145.7	146.4	148.3	147.9	0.64
1Linear effect of floor space; 2Quadratic effect of floor space.