Effects of coated proteases on the performance, nutrient retention, gut morphology and carcass traits of broilers fed corn or sorghum based diets supplemented with soybean meal

The effects of proteases on the performance, nutrient retention, gut morphology and carcass traits of broilers fed corn or sorghum based diets supplemented with soybean meal were studied in this experiment. A total of 256 male Arbor Acre broilers (one-day-old and weighing 43.8±1.31g) were randomly allotted to 1 of 4 treatments in a 2×2 factorial arrangement that included diet type (corn vs. sorghum) and protease supplementation (0 vs. 150mg/kg). The feeding program consisted of a starter diet fed from d 1 to 21 and a finisher diet fed from d 22 to 42. Supplementation of protease significantly increased the ADG of broilers during the finisher phase (P<0.01) and the overall experiment (P<0.05). Diet type had no effect on the performance of broilers during the starter phase, the finisher phase or the overall experiment (P>0.05). From d 19 to 21, the AME and DM, GE and nitrogen retention were all increased by supplementation with protease (P<0.05). Moreover, the birds fed sorghum-based diets showed a trend towards decreased AME and retention of GE (P=0.05) and nitrogen (P=0.08). From d 40 to 42, the AME and the retention of DM, GE and nitrogen were all increased (P<0.05) by supplementation with protease. On d 21, the birds fed diets supplemented with protease had significantly increased villus height and villus height:crypt depth ratio as well as decreased crypt depth in the duodenum, jejunum and ileum (P<0.01). On d 42, increased villus height, villus height:crypt depth ratio and decreased crypt depth were observed in the jejunum of broilers fed diets containing protease (P<0.05). Supplementing protease significantly increased breast muscle weight, pH24h value and decreased breast muscle drip loss (P<0.05). In conclusion, compound protease supplementation enhanced ADG of broilers during finisher phase and overall period. The AME and DM, GE and nitrogen retention and gut morphology of broilers fed diets supplemented protease were improved in the starter phase. Supplementing protease increased slaughter weight, breast muscle weight and pH24h value while decreasing breast muscle drip loss. Furthermore, low tannin sorghum-based diets generated similar performance compared with broilers fed corn-based diets.