PERFIL FERMENTATICO,COMPOSIÇÃO QUÍMICA E ESTABILIDADE AERÓBICA DE SILAGENS DE MILHO (Zea mays) ACRESCIDAS COM CAPIM TIFTON-85 (Cynodon spp.)

Abstract

The objective of this study was to evaluate the fermentation profile, microbiological growth, bromatological composition and aerobic stability of corn silage (Zea mays) with different inclusion levels of tifton-85 grass (Cynodon spp.). The levels were equal to 0, 25, 50, 75 and 100% based on the natural matter (NM), where the treatments: T1 = 100% corn silage; T2 = 75% corn silage with the inclusion of 25% tifton-85 grass; T3 = 50% corn silage and 50% tifton-85 grass; T4 = 25% corn silage and 75% tifton-85 grass and T5 = 100% tifton-85 grass silage. Microbiological analyzes were performed to count lactic acid bacteria (LAB), yeasts and fungi filaments by surface plating in BDA medium. Chemical-bromatological analyzes, fermentative losses and dry matter recovery were performed by silage sampling. The silages aerobic stability was evaluated by their temperature when exposed to the air. The experimental design was completely randomized and the data were submitted to analysis of normality of the residues using the Shapiro-Wilk tests at 5% of significance and a polynomial regression study was performed. The substitution up to the 38.8% NM level reduced the effluent production (P <0.05). There was a linear reduction in dry matter recovery with increasing substitution levels (P <0.05). The organic acids in the final opening period showed quadratic behavior, except for the propionic acid which was linear (P <0.05). The pH values had a linear and increasing behavior when the opening occurred on days 2 and 7 and quadratic for openings after day 14, 21 and 60 (P <0.05). The 51.50% NMlevel guaranteed the lowest proteolysis of the silage (P <0.05). The 40% NMlevelpresented the highest dry matter digestibility (P <0.05). There was a linear reduction in fungal counts during aerobic stability with increasing substitution levels (P <0.05). Greater aerobic stability was verified for silages with higher proportions of Tifton 85 grass. The 40% NMlevel guarantees the balance between fermentative losses, nutritive value and aerobic stability of silages.