Acacia mearnsii tannin extract as a feed additive: impact on feed intake, digestibility and nitrogen excretion by sheep fed a tropical grass-based diet

EnglishThe aim of this study was to evaluate the effect of the dietary inclusion of Acacia mearnsii tannin extract (TA) on nutrients intake and digestibility, and nitrogen (N) retention by sheep given a tropical grass-based diet. The trial was conducted with six castrated male sheep in a cross-over design in two 21-days experimental periods. The sheep were housed in metabolic cages and offered Tifton 85 hay (Cynodon dactylon) ad libitum plus concentrate at a rate of 12 g of dry matter (DM)/kg body weight (BW). The treatments were concentrate without (Control) or with 10 g TA/kg DM (Tannin). Concentration of TA in the diet was 3.8 g/kg DM and did not affect the feed intake or apparent digestibility. The TA decreased the true digestibility of n compounds (P portuguesO objetivo do presente estudo foi avaliar o efeito da inclusao alimentar de extrato tanifero de Acacia mearnsii (TA) sobre o consumo, a digestibilidade e a retencao de nitrogenio (N) em ovinos alimentados com uma dieta a base de graminea tropical. O experimento foi conduzido com seis ovinos machos castrados, em delineamento em reversao simples, com dois periodos experimentais de 21 dias cada. Os animais foram alojados em gaiolas metabolicas e alimentadas ad libitum com feno de Tifton 85 (Cynodon dactylon) mais concentrado oferecido a uma taxa de 12 g de materia seca (MS)/kg de peso corporal. Os tratamentos foram: concentrado sem (Controle) ou com 10 g de TA/kg MS (Tanino). A concentracao de TA na dieta foi de 3,8 g/kg MS e nao afetou o consumo e nem a digestibilidade aparente dos nutrientes. O TA diminuiu a digestibilidade verdadeira do N (P