Effect Of Enzyme Preparations And Dietary Energy On Performance And Digestive Physiology Of Broilers

The purpose of this study was to evaluate the effects of three different enzyme preparations in two metabolizable energy (ME) diets on growth performance, carcass properties, digestive physiology and energy utilization on broilers. No enzyme,0.02%enzyme1,0.01%enzyme2and0.05%enzyme3were added respectively in positive (PC) or negative control group (NC,-418.4kJ/kg ME reduction) with corn-soybean meal (SBM) in a2x4factorial design in a42-day experiment. A total of1200COBB-500mail broilers (1-d-old) were randomly allocated to8treatments with10pens of15broilers. A metabolic experiment described by Sibbald was conducted after growth experiment. The results showed that there was no significant difference on BW, BWG, and AFI in1～21d,22-42d or1～42d for diets, enzymes or their interactions, while the AFI at22-42d and1～42d was significantly decreased with the addition of enzyme3(P<0.05) while tended to be decreased with the addition of enzyme1and2. The F/G was significantly increased by NC diet but decreased by the addition of enzymes especially in NC diet (P<0.05). The F/G for enzyme1,2and3in NC diet came up with that in PC diet. The AME and TME in PC or NC diet were increased significantly by enzyme3or by enzyme2in NC diet (P<0.05). Half-eviscerated yield and eviscerated yield were improved by the addition of enzymes in PC diet (P<0.05). There was no significant difference on digestive organ weight and intestine length for diets, enzymes or their interactions (P>0.05). The21-d V/C of jejunum and ileum were significantly increased by the addition of enzyme1and enzyem3(P<01.05) in PC diet. The42-d villus length of duodenum and jejunum were significantly increased by enzyme3in NC diet, and the addition of enzyme2increased42-d villus length and V/C of ileum (P<0.05). The activities of21-d and42-d trypsin in pancreas were significantly increased by enzyme1and2in NC diet, enzyme1improved42-d chymotrypsin, and enzyme2improved42-d lypase and amylase (P<0.05). Enzyme1in PC diet increased the activity of trypsin in pancreas and enzyme2and3increase42-d chymotrypsin (P<0.05). The activities of21-d and42-d trypsin, chymotrypsin,21-d lypase and42-d amylase in intestinum were increased by enzyme3in PC diet, and enzyme2improved chymotrypsin (P<0.05). There was no significant difference on Lactobacillus and Conliform populations in caecum for diet, enzymes or their interaction (P>0.05). Comparing to PC diet, addition of enzymes in PC or NC diet decreased feed cost per kg body weight gain especially in NC diet (except enzyme2in PC diet) with the highest profits for enzyme3in NC diet. In conclusion, enzyme preparations improved broiler feed conversion in corn soybean meal by improving energy utilization and digestive physiology with the best influence for enzyme3in NC diet.