An experiment was conducted with the purpose of evaluating enzyme blends on the performance, carcass traits, and bone mineralization of broilers. In total, 928 one-day-old Cobb 500 male chicks of were used. A completely randomized design with four treatments with eight replicates of 29 birds each was adopted. The evaluated treatments were: 1-Positive Control (PC), feed containing the nutritional recommendations of the genetic company's manual; 2-Negative Control (NC), feed with reductions of 75 kcal/kg AME and 0.10 and 0.12 percent points of phosphorus and calcium, respectively; 3 -NC + enzyme blend (amylase + β-glucanase, xylanase, and phytase; 250 g/t of feed) and 4 -NC + enzyme complex (phytase, amylase, xylanase, glucanase, pectinase, cellulase, and protease; 200 g/t of feed). Birds fed the diet with reduced nutrient levels (NC) presented the worst performance (p<0.05). The supplementation of the enzyme blend promoted similar (p<0.05) weight gain and feed conversion ratio as those obtained with the PC diet during the period of 1-21 days of age. During the phase of 22-42 days and the entire experimental period, weight gain and feed conversion ratio improved with the use of the enzyme combinations compared with the NC group, but remained lower than the PC group. Enzymes combinations did not affect (p>0.05) carcass or parts yields. The broilers fed the reduced-nutrient and energy diet presented lower (p<0.05) tibial ash, calcium, and phosphorus contents that the other treatments. The use of enzyme combinations improved the performance of broilers fed diets with reduced nutrient and energy levels.

The objective of this study was to evaluate the effect of exogenous emulsifier and lipase in diets on performance, digestibility, and organ biometry of broiler chickens. A completely randomised design with seven treatments and seven replications was adopted. The treatments were as follows: T1 (positive control; PC): 3000, 3100, 3200, and 3250 Kcal of metabolisable energy (ME) kg-1 of diet for phases 1 to 10, 11 to 21, 22 to 31, and 32 to 37 days, respectively; T2: PC with reduction in ME of 30 Kcal kg-1 of diet; T3: PC with reduction in ME of 60 Kcal kg-1 of feed; T4 (negative control; NC): PC with reduction in ME of 90 Kcal kg-1 of feed; T5: NC with inclusion of exogenous lipase (10 000 U kg-1); T6: NC with inclusion of emulsifier (250 g t-1); and T7: NC with inclusion of lipase (10 000 U kg-1) and emulsifier (250 g t-1) in the period from 1 to 37 days of rearing. Performance characteristics (weight gain (WG), feed intake (FI), and feed conversion (FC)), carcass yield, cut yield, the relative weight of abdominal fat and organs (small intestine, liver, and pancreas), and relative intestinal length, in addition to dry matter digestibility (CDADM), ethereal extract (CDAEE), crude metabolisable energy (CMACE), and apparent metabolisable energy (AME) of the diets, were evaluated. In the initial phase, the CDAEE was higher for the PC group than for the emulsifier + lipase group. The AME determined in the final phase for the group supplemented with an emulsifier was higher by approximately 50 Kcal (EM) than the NC group. The WG of the lipase group was similar to that of the PC group. However, the groups with emulsifier and emulsifier + lipase showed a lower WG than the PC group. The additives used did not recover the FC to the same level observed in the PC group. The reduction in ME of 90 Kcal kg-1 generated a lower WG and worse FC. The use of both an emulsifier and lipase together produced results like to the PC group. The biometrics of the organs and the carcass yield and cuts were not influenced by diets. Thus, it can be concluded that the inclusion of lipase and an emulsifier improves the performance of broilers given diets with reduced energy, although it does not improve the lipid utilisation of the diets.

SUMMARY This work evaluated the effect of including sweet potato meal (SPM), as an alternative to corn in broiler chicken diets, on performance, carcass yield, intestinal morphometry, organ biometry, meat quality and drumstick pigmentation. The study used 936 male Cobb-500 chicks. The experiment had a completely randomized, 3x2 factorial design, with three diet types. These included corn as the energetic ingredient in the standard diet (corn-soybean meal, CSM), and an increasing (ISP) and decreasing (DSP) inclusion of sweet potato meal as a corn substitute, in association with exogenous enzymes, for a total of six treatments with six repetitions and 26 birds per plot. During the period of 1 to 21 days, there was an interaction (P<0.05) for the weight gain (WG) variable; the CSM diets promoted greater WG in relation to the ISP and DSP groups, when supplemented with exogenous enzymes. There was an increase (P<0.05) in surface absorption of the jejunum villi and relative weight of the pancreas, and worse feed conversion (FC), for the ISP and DSP diets. With exception of the pancreas, for the entire period of 1 to 39 days the performance, yield of the carcass and cuts, meat quality, relative weight of the liver, and feet pigmentation variables were not affected (P>0.05) by the factors evaluated. Sweet potato meal, independent of the inclusion program (ISP/DSP) and enzyme supplementation, could partially substitute corn in broiler chicken feed, guaranteeing good performance, carcass yield and meat quality.