PSII-5 Carcass characteristics and growth performance of market pigs fed reduced lysine diets in bedded hoop barns

Abstract

Abstract A 2 × 2 × 2 factorial design was used to compare the effect of SID Lys:ME concentration (current vs. reduced), stocking density (1.30 vs. 4.05 m2/pig), and harvest month (August vs. March) on pigs raised in bedded hoop barns in Western Iowa. For each harvest month, 420 pigs produced from the mating of Duroc boars (Choice Genetics; West Des Moines, IA) to Camborough females (PIC; Hendersonville, TN) were sorted into 12 pens. Six pens were inside 3 large-scale (9.1 × 18.3 m) hoop barns and were stocked with 64 pigs/pen (32 barrows and 32 gilts; 1.30 m2/ pig). Six pens were inside 3 small-scale (6.0 × 10.8 m) hoop barns and were stocked with 6 pigs/pen (3 barrows and 3 gilts; 4.05 m2/pig). Within each stocking density, pens were randomly assigned to 1 of 2 diets which were fed in 2 phases. Corn-soybean meal diets were formulated to deliver 2.94 or 2.34 g SID Lys per Mcal ME in phase 1 (72.6–95.0 kg) and 2.34 or 1.76 g SID Lys per Mcal ME in phase 2 (> 95.0 kg). Pigs were individually weighed every 28 days and feed disappearance was recorded. When pigs in a pen averaged 129.3 kg the entire pen of pigs were harvested. A single chop (last-rib location; 2.54 cm thick) was collected from each carcass to assess pork quality. Pigs harvested in the summer grew faster, more efficiently, and with more intramuscular fat than those harvested in winter (P-value ≤ 0.05) but had lower 10th rib pH (P-value < 0.0001). Pigs allotted 4.05 m2/pig grew more efficiently but had reduced last rib pH as compared to pigs stocked at 1.30 m2/pig (P-value < 0.05). Reducing SID Lys:ME did not impact growth performance or carcass characteristics (P-value > 0.10). Lower concentrations of SID Lys:ME may be adequate for pigs housed in bedded hoop barns but further study is warranted.