Inclusão de tanino condensado em dietas com alto teor de concentrado para bovinos de corte

• Autor(a) principal: Mezzomo, Rafael
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5634
• topic: PNDR; PDR; Proteína metabolizável; RUP; Metabolizable protein; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

This trial was conducted to evaluate the effect of condensed tannin (TN) associated or not with a true protein source on intake, ruminal and total digestibility, ruminal digestion rate and urinary nitrogen excretion in beef steers fed high concentrate diet (87% of DM). Four crossbred steers (407 kg of average BW) fitted with rumen cannula were assigned to a 4x4 latin square design, arranged in a 2x2 factorial arrangement. Steers were fed a basal diet based on cracked corn, whole cottonseed, sugar-cane bagasse, mineral mixture and 1 out of four supplements: soybean meal with condensed tannin (SMT); soybean meal without condensed tannin (SM); condensed tannin without soybean meal (TN) and a treatment without both soybean meal and condensed tannin (BS). Quebracho extract were used as tannin source, included to provide 4 g of tannin/100 g of diet DM. Intake of DM and nutrients was not affected (P>0.10) by TN supplementation. However, there was an effect (P<0.10) of TN supplementation on ether extract digestibility. A smaller (P<0.10) concentration of urinary urea nitrogen (71.94 vs. 53.62) and total nitrogen (86.43 vs. 74.07) were observed in the animals supplemented with condensed tannin. Serum urea nitrogen concentration did not differ (P>0.10) among treatments. There was an interaction (P<0.10) between condensed tannin and soybean mean on ruminal digestibility and digestion rate of crude protein (CP), where when supplemented with soybean meal the condensed tannin reduced the ruminal digestibility of 46.92 to 33.46 and consequently, reduced the digestion rate of CP. Crude protein intake increased (P<0.10) with the inclusion of soybean meal in the supplement. No differences in DM passage rate were observed (P>0.10) among treatments. Urinary urea nitrogen and total nitrogen were higher in the animals supplemented with soybean meal. The nitrogen balance indicated that the use of TN improved the efficiency of nitrogen utilization (P<0.10), however, no differences were observed when soybean meal was added to the diet (P>0.10). There was an interaction (P<0.10) between condensed tannin and soybean mean supplementation on flux of rumen undegradable protein (RUP), metabolizable protein (MP) and on the ratio MP:CP. In the presence of soybean meal the addition of TN increased the flux of RUP (302.24 to 416.02), MP (540.23 to 671.03) and improved the ratio MP:CP (58.69 to 46.54). The yield of microbial protein on the abomasum and the microbial efficiency did not differ among treatments (P>0.10). There was no effect of TN supplementation (P>0.10) on ruminal pH, VFA and ammonia (N-NH3) concentration. N-NH3 increased and ruminal pH decreased with the inclusion of soybean meal (P<0.10) in the diet. The use of condensed tannin as an additive in cattle fed high concentrate diet using soybean meal as true protein source decreases the digestion rate and ruminal degradability of crude protein without affecting feed intake. The utilization of condensed tannin as an additive in cattle fed high concentrate diet using soybean meal as true protein source implies in positive effects on efficiency of N utilization, increasing the flux of metabolizable and decreasing nitrogen excretion with no changes in ruminal fermentation, optimizing the nitrogen assimilation by the animal.