Avaliação de espécies forrageiras disponíveis para ruminantes no semiárido

Abstract

Considering the importance of food diversity available for feeding ruminants in the semiarid aimed to estimate the nutritional value of the following forage species: maniçoba (Manihot psedoglazziovii Pax. & Hoffm); sabiá (Mimosa caesapiniifolia Benth); mororó (Bauhinia Bauhinia cheilantha (Bong.) Steud.); Leucaena (Leucaena leucocephala Lam.); cunhã (Clitorea ternatea) and Gliricidia (Gliricidia sepium), from the chemical composition, carbohydrates and proteins fractionations, degradation parameters and ruminal fermentation, in vitro digestibility of dry matter and also ruminal and post-rumen protein degradation. The samples were collected in four replicates per species in the Experimental Caatinga Field of Embrapa Semi-Arid (CPATSA Petrolina City, state of Pernambuco. The concentrations of carbohydrates and protein fractionations were determined based on the Cornell Net Carbohydrate and Protein System (CNCPS). The evaluation of the degradation of organic matter and products of ruminal fermentation was performed using in vitro semiautomatic gas production technique. Ruminal degradability and intestinal digestibility of protein were estimated using the three steps technique. Although all the evaluated species presented crude protein above 110 g/kg DM, and the leucaena followed by manioc, stood out showing the highest levels (P <.05). The highest concentrations (P <0.05) of total phenols (FT), total tannins (TT) and condensed tannins (CT) were found in sabiá and mororó species, and considering the other species evaluated there are not variation. Cunhã species followed by Leucaena had the highest concentration of the B2 fraction (potentially digestible fiber) and the other species did not differ (P> 0.05) among themselves. The C fraction (unavailable fiber fraction) was found in greater amounts (P <0.05) in sabiá and mororó. The nitrogen fractions of high and medium ruminal degradation were found in higher concentrations in cunhã and leucaena, in relation to sabiá which had the lowest concentration. Fraction C, which corresponds to the unavailable nitrogen to animal metabolism was higher in sabiá and mororó species (P <0.05) and lower for cunhã, leucaena and maniçoba species. Maniçoba, gliricídia and to a lesser extent, leucaena provided higher (P <0.05) truly degradation of organic matter (TDMO g/kg OM), otherwise sabiá and mororó showed less values. Gliricídia, leucaena and maniçoba stood out, showing high digestibility potential (P <0.05).The cunhã had the highest percentage of rumen degradable protein (RDP) and the lowest percentage (P <0.05) of ruminal non degradable protein (RUP %CP). The leucaena presented higher intestinal protein digestibility (ID g/kg DM) as well as higher values of digestible RUP (RUPd g/kg DM). Gliricídia, Leucaena and maniçoba presented potential for reducing enteric CH4 production, without any effect on the nutrients degradation, digestibility and supply of readily fermentable carbohydrates high potential. The leucaena stands out as a source of rumen protected protein degradation and released in the intestine.