In recent years the high fixed costs of confinement swine finishing buildings, coupled with increased pressure from environmental, community, and animal welfare groups have led swine farmers to explore hoop buildings as an alternative housing system. This experiment examined the growth and development of finishing pigs in relation to housing environment, and the seasonal effects of raising finishing pigs in bedded hoop or confinement buildings using serial ultrasound measurements of backfat thickness and loin muscle area, plus serial weighing during the finishing period.

Pigs were either housed in a (9.1 × 18.3 m) hoop finishing building (designed to hold 150 pigs in one pen) or a mechanically ventilated, totally slatted confinement building (designed with six pens holding 22 pigs per pen). Feeder pigs were placed in the pens at 16 kg and were marketed at 124 kg. Pigs were randomly selected from the hoop building (n=48) and eight pigs from each of the six pens in the confinement building (n=48). All pigs were provided ad-libitum access to corn soy diets. Pigs were weighed and ultrasound images were recorded every 14 days during the last 56 days of the finishing phase. All pigs were scanned by a certified technician using an Aloka 500- V SSD ultrasound machine. Two trials were conducted— one in summer (April–August) and one in winter (October– February). Comparisons were made between hoop and confinement buildings within a season (summer and winter) and for the seasons combined. Comparisons, between seasons within building type (hoop or confinement) were also made.

Preliminary results indicate that although pigs in each building type reached a similar end weight at about the same time, hoop-fed pigs displayed more variation during the finishing period. Confinement-fed pigs in both seasons grew at a more constant rate. Environmental or seasonal variation may have more impact on growth, and fat and muscle deposition for pigs finished in bedded hoop buildings than pigs in confinement buildings. Also, differences in social structure and number of feeder holes in relation to pig number may impact appetite and feeding time causing more variation in live weight due to gut fill. Further research could be conducted to reduce the variability in growth caused in hoop buildings. Modifying diets, providing supplemental heat during the first 30 days pigs are placed in hoop buildings, and/or placing pigs into hoop buildings at heavier weights are all possible solutions that need further investigation.