Valor nutritivo e degradabilidade ruminal da silagem de capim-braquiaria com inclusão de farelo de arroz

Abstract

Two experiments were conducted to evaluate losses and effluent gases, fermentation characteristics, chemical composition, protein fractions and carbohydrates, as well as to estimate the kinetic parameters of in situ ruminal degradability of Brachiaria decumbens silages added with rice meal. It was evaluated the inclusion of 0, 10, 20, 30 and 40% rice meal in the Brachiaria silage, distributed in a completely randomized design with five replications. After the uniformity cut the grass, held at the height of 5 cm from ground level, was made fertilization with 60 kg/ha of nitrogen and 60 kg/ha of potassium in the form of ammonium sulfate and potassium chloride, respectively. After 5 days of regrowth and cut to 10 cm of soil, held ensiling of Bracharia in experimental bags of 10 L, equipped with Bunsen valve and 03 kg of sand in the bottom to hold the effluent. The bags were opened after 40 days. Data were subjected to analysis of variance, and when significant, were subjected to regression analysis. The values of gas and effluent losses were reduced linearly, estimated reduction of 0.11 and 0.39 percentage units, respectively, and the recovery of dry matter silages with the inclusion of rice meal increased linearly, estimating percentage increase of 0.32 units for each 1% of rice meal. There was a quadratic effect of pH values and a linear for values of N-ammonia and buffering capacity, estimated to decline by 0.11 and 0.05% for each 1% inclusion of rice meal in ensiling. The concentrations of acetic acid, propionic acid and butyric acid have been reduced linearly by 0.01, 0.0008, and 0.0006 percent unit for each 1% of rice meal while lactic acid increased linearly by 0.05 percentage units. Each unit percentage rice meal promoted linear increase of 0.43, 0.18, 0.71 and 0.70% in dry matter (DM), crude protein, ether extract and total digestible nutrients, and reduced linear 0.69, 0.43 and 0.26% in the levels of neutral detergent fiber, acid detergent fiber and hemicellulose. The addition of rice meal caused a linear reduction of the total carbohydrates (TC), fibrous carbohydrates, as well as the fraction of CT C depending on the levels of inclusion of rice meal, an estimated reduction of 0.16, 1, ix 15 and 0.98 percentage units. The protein fraction was increased linearly at 0.64 percentage units for each 1% rice meal added to silage. For nitrogen fractions B3 and C decreased 0.11% and 0.40% for each percentage unit of rice meal added to the silage, respectively. For the parameters of the ruminal degradability of DM was estimated increase in fractions A I and fraction decrease, estimated at 0.54 and 0.04 percentage units for each 1% of rice meal added, respectively. For the rate of degradation of fraction B (c), no effect depending on the levels of rice meal. Fractions A and I of the parameters of increased protein degradability of 0.22 and 0.72 percentage units with the addition of 1% of rice meal. The inclusion of 10% of rice meal at the time of ensiling grass ensures the reduction of losses effluent and gases, improves the fermentation and chemical composition, in addition to providing improvement in carbohydrate and protein fractions as well as of ruminal dry matter, crude protein and neutral detergent fiber.