Growth performance, pork quality, and excretion characteristics of pigs fed Bt corn or non-genetically modified corn at two slaughter weights

To compare growth performance and carcass characteristics, 64 pigs (average initial BW = 62 kg) were fed diets containing Bt corn (Bt: Syngenta Bt 11 event) or control corn grain (C: pooled non-biotechnology derived inbred lines). Pigs were blocked by sex and weight and allocated into 16 pens equally. Isocaloric, isonitrogenous diets contained an indigestible marker. Feed and water were provided ad libitum. Feed disappearance and weight gain data, and fecal samples were collected weekly. At slaughter, pigs were divided into two groups based on market weight: 1 (85 kg) and 2 (100 kg). No difference in ADG was observed between pits fed C and Bt diets for harvest weight groups. Feed efficiency was greatest for pigs fed the C diet (P=.002) and was not different between 1 and 2 pigs. An interaction between corn and harvest weight was observed. No corn effects were observed for hot carcass weight; loin eye area; and 1st, 10th, last rib, and last lumbar vertebrae fat. Harvest weight differences were observed; lighter weight pigs had smaller loin eye area (12.4 cm2 vs. 15.7 cm2; P\u3c.0001) and less backfat. Across both market weight groups, gilts had larger LEA (P\u3c.05) and were leaner than barrows. No harvest weight and corn source effects were observed for meat tenderness and drip loss. Hunter color \u27b\u27 values were greater for pigs fed C diets (11.71 vs. 11.31; P=.02) and group 2 pigs (11.77 vs. 11.26; P=.005). There were no significant differences in DM, ether extract, or CP content of meat samples. No corn effects were observed for N or P content of fecal and urine samples. There were no differences in apparent digestibility of N between pigs fed Bt and C diets. Pigs fed C diets had greater apparent P digestibility (57.8% vs. 40.2%; P\u3c.0001). Interactions were observed between treatment and sex; barrows fed Bt corn and gilts fed C corn had lowest apparent P digestibilities. Findings suggest no detrimental effects on growth performance or carcass and excretion characteristics for growing-finishing pigs fed Bt corn. Traits desired by consumers were not different between pigs harvested at light and heavy market weights