Aditivos e tempo de armazenamento afetam o valor nutritivo e estabilidade aeróbia de silagens de resto de cultura do abacaxi?

Abstract

This study aimed to evaluate the effect of the use of additives and storage time on quality, in vitro digestibility and aerobic stability of silages from pineapple (Ananas comosus (L) Merr.) crop residue. Thirty-six experimental silos, made of PVC, were distributed into a completely random design, in a 3 × 3 factorial arrangement (three treatments, PCRE silage without additives, PCRE silage added with corn meal and PCRE silage added with wheat bran and three storage times: 60, 90 and 120 days), with four repetitions (silos). The additives were mixed at a proportion of 20% compared to 80% of PCRE, based on the natural matter. After each storage time, silos were opened and the losses quantification (gases and effluent) were done, besides the pH measurement, water-soluble carbohydrate quantification, buffer capacity, and assessments of chemical composition and the in vitro digestibility of dry matter, organic matter, and neutral detergent fiber. The assessment of aerobic stability was done after each storage time, from the beginning of silages exposition to the air for 1, 3, 6 and 9 days, with the quantification of CO2 production (g/kg DM) and ammonia nitrogen content (NH3-N), measurement of pH and the determination of DM, CP and FDN contents. All variables of the aerobic stability were analyzed as repeated measurements. Data were submitted to analysis of variance with the aid of SAS® and the means were compared by the Tukey’s test at 5% of probability. Silages added with corn meal and wheat bran presented greater (P<0.05) dry matter content (298.7 and 297.6 g/kg) than the control silage (182.1 g/kg). The longer storage times resulted in a greater total dry matter loss and an effluent production in all treatments. The treatment PCREsil + CM presented greater digestibility values of DM, OM and NDF (739.7; 751.0 and 704.8 g/kg, respectively). The control silage (PCREsil) presented an increase of CO2 production already at the first days of air exposition, while in the added silages, this increase started only from the 6th day, a fact that denotes the efficiency of additives to maintain stable silages for a longer time, after the air exposition. The use of corn meal as an additive of PCRE silages provides greater storage time, affords a better digestibility of the ensiled material, and either reduces the deterioration speed of these silages.