Associação de xilanase, protease e dois níveis de fitase em dietas de frangos

Abstract

Two trial were conducted at the School of Veterinary and Animal Science / UFG to evaluate the combination of xylanase, protease and two levels of phytase in diets of chickens from 1 to 42 days old. The experimental design of both experiments was completely randomized in a 2x2x2 factorial arrangement, with two inclusions of phytase (750 FTU and 1500 FTU), xylanase (with and without xylanase) and protease (with and without protease). In the first trial, 1536 male Ross 308AP chicks were housed, raised in a floor shed with litter, until 42 days, consisting of 8 treatments, 6 replications of 32 birds. In the second experiment, 480 male chicks Cobb500 strain were housed, reared in batteries up to 42 days old, subjected to 8 treatments, 6 replications of 10 birds (1 to 21 days) and in the other phases (22 to 42 days) by 8 treatments, 5 replications of 4 birds. In the first trial, the use of xylanase or protease in diets with 750 FTU of phytase influenced the improvement in feed conversion of chickens at 42 days old. The use of xylanase promoved a higher chicken breast at 42 days. The use of 1500 FTU of phytase obtained higher thigh and drumstick yields. Diets containing xylanase and protease obtained higher wing yield. The use of 750 FTU of phytase and protease in the diet showed lower abdominal fat. Xylanase and protease in diets containing higher levels of phytase showed a higher content of dry matter and protein in the chicken breast. The increase in phytase dosage promoted an increase in mineral matter in the birds' breasts. There was an effect of protease in the diet in increasing the potassium content. The use of phytase and xylanase increased the zinc content in the breast. The inclusion of enzymes did not influence the metabolizability of chickens at 21 days. In the second experiment, the use of 1500 FTU of phytase associated with protease in the feed promoted improvement in the feed conversion of chicks at 7 days. The inclusion of 1500 FTU with xylanase in the diet increased weight gain in chickens at 41 days. Diets containing 750 FTU of phytase containing xylanase or protease showed an increase in the nitrogen metabolizability coefficient of chickens at 21 days. The highest level of phytase with protease in the diet promoted an increase in apparent metabolizable energy. The increase in the yield of chicken thigh + drumstick at 42 days was observed in diets with phytase containing protease in the diet. There was an increase in amino acids in the chemical composition of chicken breast at 21 days, observed in birds fed 1500 FTU of phytase. Effect also observed at 42 days, with the inclusion of 1500 FTU of phytase and protease in the diet. In the serum biochemical levels of chickens at 21 days of age, the increase in the dosage of phytase associated with xylanase and protease influenced the serum levels of globulin, total proteins, total and ionic calcium and phosphorus. In the serum levels of chickens at 42 days of age, birds fed 750 FTU of phytase containing xylanase influenced the increase in albumin, Ca ionic and P. Xylanase and protease contributed to improve bone characteristics of chickens fed with increasing levels phytase at 21 and 42 days of age.