Níveis de energia metabolizável de dietas para frangos de corte suplementadas com enzimas exógenas e posbiótico

Abstract

This study aimed to evaluate different energy leves, as well as the inclusion or not of enzymatic blend and post-biotic in broiler diets on performance, carcass yield, cecal microbiota composition, short chain fatty acids profile of cecal content, digestive and pancreatic enzymatic activity, and economic analysis of production. For this purpose, a total of 2,592 one-day-old, male, broiler chicks were distributed in a completely randomized design, in a 3 x 2 x 2 factorial scheme (three energy levels – high (1 to 7 days: 3050 kcal kg-1; 8 to 21 days: 3225 kcal kg-1; 22 to 28 days: 3280 kcal kg-1; 29 to 35 days: 3320 kcal kg-1 and 36 to 42 days: 3360 kcal kg-1), intermediate (reduction of 40 kcal kg-1 for the phase from 1 to 7 days and 80 kcal kg-1 for the other phases) and low (reduction of 80 kcal kg-1 for the phase from 1 to 7 days and 160 kcal kg1 for the other phases) x inclusion or not of enzymatic blend x inclusion or not of postbiotic), totaling 12 treatments, with nine replications and 24 birds per experimental unit. The highest energy density provided the best performance and the use of additives was not able to improve improvements. At 42 days of age, the birds presented similar weight gain between treatments. At 28 days of age, there was an increase in the presence of the phylum Tenericutes with the addition of the postbiotic in the diet. At the family level, the high energy level reduced the prevalence of Streptococcaceae and the addition of postbiotic increased the predominance of O_RF39;F_ and decreased the prevalence of Ruminococcaecae. The concentration of acetic acid decreased when the birds fed diet with the lowest energy level. Higher trypsin and chymotrypsin activity were observed at 21 and 28 days of age in birds that consumed lowenergy diets. The addition of enzymatic blend decreased lipase activity at 21 days of age of birds, while postbiotic increased the activity of this enzyme. At 42 days of age, carcass and breast yield were higher in birds that received the lowest energy diet and the highest percentage of abdominal fat was observed for birds fed diets with higher energy density. The more energetic diet increased 10 cents in the cost of the chicken kilo produced and, regarding the additives, the inclusion of the enzymatic blend provided a 17 cents reduction in production cost (kg/chicken). In conclusion, diets with high and intermediate energy levels did not cause intestinal dysbiosis, however, their use is not justified taking into account weight gain, carcass and breast yield, percentage of abdominal fat and production cost. Considering the total period of rearing and the economic analysis, the dietary inclusion of enzymatic blend was beneficial, while the addition of postbiotic was not able to modulate the cecal microbiota, without interfering on performance.