Sugarcane yeast (Saccharomyces cerevisiae) and -mannanase enzyme in broilers' diets

Our objective was to evaluate the effect of supplementing beta-mannanase enzyme, with and without sugarcane yeast (Saccharomyces cerevisiae), on broiler chickens aged 1-21 days. The study used 720 one-day-old male Cobb chicks in a randomized design, with six treatments and six replications of 20 birds each. The treatments were: basal diet (BD), BD + beta-mannanase ((100 g/t)), 7% sugarcane yeast (SY), SY + beta-mannanase ((80 g/t)), SY + beta-mannanase (100 g/t), and SY + beta-mannanase ((120 g/t)). Zootechnical results (animal performance) were evaluated during the pre-starter (1 to 7 day-old) and starter (1 to 21 day-old) phases, as well as small intestine morphometry (duodenum, jejunum, and ileum) and diets' economic viability. Data were subjected to variance analysis using the SAS software, and the means were compared by the Student Newman Keuls (SNK) test. In the pre-starter phase, treatments with YD + beta-mannanase (80, 100, and 120 g/t) showed the best feed conversion averages. In the starter phase, chickens consuming the basal diet (BD) and BD + beta-mannanase showed better average weights, weight gains, and feed conversion rates. For intestinal morphometry, shallower ileal crypts were observed in the treatment with YD + beta-mannanase ((120 g/t)) compared to the basal diet, and wider ileal villi were observed in the treatment with YD + beta-mannanase ((100 g/t)) compared to the diet with YD + beta-mannanase ((80 g/t)). The thickness of the muscular wall in the duodenum was lower in chickens consuming BD compared to BD + beta-mannanase ((100 g/t)), higher in YD and supplementation with 100 g/t compared to 80 and 120 g/t in the jejunum, and higher in diets with beta-mannanase supplementation compared to BD and YD in the ileum. For economic viability, adding 7% sugar cane yeast, with or without enzyme, increased the average feed cost and cost index, and reduced the economic efficiency index. Based on the zootechnical results, YD + beta-mannanase ((120 g/t)) is recommended for the pre-starter and starter phases. However, using sugar cane yeast with or without beta-mannanase enzyme supplementation is not economically viable in the 1- to 21-day period.