Banca de DEFESA: ANTÔNIA RAFAELA DA SILVA OLIVEIRA

ADDITION OF PURIFIED CONDENSED TANNINS FROM Mimosa tenuiflora (Willd.) Poir.) AS ADDITIVE IN DIETS COMPOSED OF DIFFERENT SEMI-ARID FORAGE LEGUMES

digestibility; forage legumes; fractionation; in vitro gas production; secondary compounds;

Several biomolecules have been studied as potential phytogenic additives in ruminant feed, enabling increased productivity and reduced environmental impacts. Considering the importance of the diversity of species available for feeding ruminants in the Semiarid region, the objective was to estimate the effect of increasing doses of condensed tannin extract from Mimosa tenuiflora: 0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% of dry matter (DM) of the diet as an additive in diets composed of different sources of protein from native and exotic legumes: cunhã, gliricidia and jureminha, on digestibility, degradability and production of gases in vitro. The diets were composed of 65% roughage (25% tifton-85 hay, 10% elephant ear cactus and 30% one of the legumes), the concentrate represented 35% of the DM of the diet (23% crushed corn , 10% soybean meal, 1% livestock urea and 1% commercial mineral mixture). Analyzes of chemical composition, protein fractionation, ruminal degradation and fermentation parameters, in vitro digestibility of dry matter and ruminal degradation were carried out. The legume samples to compose the diets and for the extraction of TC were collected, in five replications per species, on the experimental farm of the Universidade Federal Rural de Pernambuco (UFRPE), in the municipality of Garanhuns-PE. Protein fractionation was performed based on the Cornell Net Carbohydrate and Protein System (CNCPS). The evaluation of the degradation of organic matter and rumen fermentation products was carried out using the semi-automatic in vitro gas production technique. Rumen degradability and nutrient digestibility were estimated using the two-stage technique. All species evaluated presented crude protein (CP) levels above 230 g/kg DM, however, cunhã stood out, presenting the highest levels of CP (350.65 g/kg DM) and protein fraction A (30. 10 g/kg DM). Gliricidia and jureminha presented higher concentrations of the B1 + B2 fraction of the protein, 69.57 and 67.44 g/kg CP, respectively. The C fraction, which corresponds to nitrogen unavailable for animal metabolism, was higher in the jureminha species (P<0.05) and lower for the cunhã and gliricidia species. There was an interaction between the protein sources in the diet (cunhã, gliricidia and jureminha) and the TC levels for total gas production (P<0.05), however, no interaction was observed for the dietary degradation parameters. The diet with gliricidia showed high digestibility potential regardless of the addition of TC, presenting DIVMS of 874.9 g/kg with zero tannin, followed by cunhã with 725.8 g/kg. The addition of TC linearly decreased the digestibility of the diets and, regardless of the addition of TC, jureminha showed lower true DM digestibility. The legume cunhã showed the potential to constitute part of the protein in diets formulated for ruminant animals. The inclusion of purified TC extract from jurema preta resulted in a reduction in ruminal degradation rates. Therefore, it can be concluded that, in plants naturally rich in tannins, it is not necessary to further increase the concentration of these compounds.