Comparison of Swine Performance When Fed Diets Containing Roundup Ready® Corn, Parental Line Corn, or Two Commercial Corns

This experiment was conducted to evaluate growth performance and carcass quality measurements in growing-finishing pigs fed diets containing either Roundup Ready® corn expressing the CP4 EPSPS protein, the parental control corn, or two commercial sources of nongenetically modified corn. The experiment used 72 barrows and 72 gilts with an initial body weight of 50 lb. The pigs were allotted to a randomized complete block design with a 2 x 4 factorial arrangement of treatments (two sexes x four corn hybrids). The experiment continued until the average body weight was 255 lb, at which time all pigs were slaughtered. Realtime ultrasound measurements were taken on the final day of the experiment. Carcass quality measurements were made 24 hours postmortem. Average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (ADG/ADFI) were not affected by corn variety, but there was an effect of sex for all growth performance traits, with barrows having greater (P \u3c 0.001) ADG and ADFI than gilts and gilts having better (P \u3c 0.001) feed efficiency than barrows. Real-time ultrasound measurements were similar among corns, however a sex effect was detected for backfat (BF) depth, with gilts having less (P \u3c 0.001) BF than barrows. There were no differences in carcass midline BF measurements among corns, but there was a significant difference between barrows and gilts, with gilts having less (P \u3c 0.05) BF than barrows. Total body electrical conductivity measurements were not affected by corn, but hot carcass weight was greater (P \u3c 0.001) in barrows than gilts. Also, primal percentage and percent carcass lean were greater (P \u3c 0.01) in gilts than barrows. Longissimus muscle quality scores were similar among corns and between barrows and gilts, except for pH, which was greater (P \u3c 0.05) in barrows than gilts. Analysis of longissimus muscle composition revealed no main effect of corn variety (P \u3e 0.05) or effect of sex (P \u3e 0.05) for protein, fat, and water percentages. Roundup Ready® corn (2.99%) differed (P \u3c 0.04) from parental control corn (2.20%) but not commercial corns (3.08 and 3.06%) in longissimus fat content. In summary, there were no differences in growth performance or carcass measurements in growing-finishing pigs fed diets containing either Roundup Ready® corn, the parental control corn, or two commercial sources of non-genetically modified corn. Roundup Ready® corn can replace traditional corn in diets for growing-finishing pigs