Taninos condensados oriundos do estrato de Acácia Mearnsii na alimentação de cabritos em terminação

Abstract

Two experiments were performed to determine the best level (0, 16, 32 and 48 g/kg DM) of inclusion of condensed tannins (CT) from Acacia mearnsii extract in the diet of goat kids in feedlot. An experiment was performed with thirty-two castrated crossbreed Boer goat kids, with a mean age of four months and mean body weight (BW) of 19.7 ± 2.05 kg, to measure nutrient intake and performance, and another experiment was developed with twenty Boer animals, at five months of age and 29.0 ± 2.45 kg BW, in which the digestibility coefficients, nitrogen balance, microbial protein synthesis, ingestive behavior and serum urea nitrogen (SUN) were determined. The intake of dry mater (DM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), nonfibrous carbohydrates (NFC) and total digestible nutrients (TDN) did not change significantly (P>0.05) with the addition of Acacia mearnsii extract in the goat kid diets, but the NDF g/kg BW (P=0.03) and BW0.75 (P=0.04) increased. No effect was observed on the addition of condensed tannins on the time spent on rumination (P=0.45), idling (P=0.11), chewing (P=0.84), nº chews/bolus (P=0.41) or eating and the rumination efficiency of DM and NDF (P>0.05) of the goat kids. A tendency was observed to increase the time spent feeding (P=0.07) but with marked responses only at CT inclusion above 32 g/kg DM. The digestibility of DM, CP, NDF, NFC and TDN decreased in goat kids, and EE (P = 0.80) digestibility was not affected by an increase in the condensed tannins. No effect of Acacia mearnsii extract levels was observed on the N intake (P=0.66) and N retained (P=0.11); however, a linear increase in fecal N excretion (P<0.01) and a trend for a linear decrease in urinary N excretion (P=0.08) were observed. A quadratic increase was observed for the synthesis (P<0.01) and microbial efficiency (P<0.01), final body weight (P=0.01), ADG (P=0.01), total gain (P=0.01), the Gain:Feed ratio, hot weight (P=0.02), and cold (P=0.03) carcass weights, as well as for the hot (P=0.03) and cold (P=0.04) carcass yields. The loin eye area was not affected (P=0.75). The inclusion of condensed tannins from Acacia mearnsii extract up to 17.7 g/kg DM is recommended, as it improves the synthesis and efficiency of microbial production, increasing the Gain:Feed ratio and performance of animals.