The influence of environment on the growth of commercial finisher pigs

Methods: Forty–eight barrows were selected at 11 weeks of age from a commercial nursery and randomly assigned either to the environments of the adjoining commercial grower and finisher buildings (n=24) (COMM group) or an unrestricting research environment (n=24) (UNRES group). Pigs were weighed at biweekly intervals from placement at 30 kg (65 lb) liveweight until slaughter. Backfat thickness and loin eye area were measured by Bmode ultrasound every 28 days until the mean liveweight of the group was 91 kg (200 lb) and then biweekly to 120 kg (265 lb), when the entire group went to slaughter. Fat-free carcass lean and total carcass fat were predicted using equations including liveweight, ultrasonic backfat depth, and ultrasonic loin eye measurements. Serum collected at 11, 13, 15, 19, and 23 weeks of age were evaluated for α-1-acid glycoprotein (AGP), insulin-like growth factor-1 (IGF-1), and haptoglobin. Whole blood was collected at 11 and 23 weeks of age for lymphocyte phenotyping (CD4, CD8).