FIBROLYTIC ACTIVITY AND EFFECTS OF AUTOCHTHONOUS FUNGAL STRAINS FROM DIGESTIVE TRACT IN DIET FOR WEANED LAMBS

Resumen

The aim of this study was to evaluate the cellulase and xylanase activity of fungi isolated from the digestive tract of sheep and the effects of supplementation with two selected fungi on intake, digestibility, microbial protein (MP) synthesis and nitrogen balance in lambs. The first experiment evaluated the carboxymethylcellulase (CMCase) and xylanase activities from two filamentous fungi and two yeasts, which were grown in a culture medium containing Urochloa decumbens hay. The second experiment was performed with twenty-one male Santa Inês x Dorper crossbred lambs, with initial body weight of 18.80 ± 0.55 kg, distributed in a completely randomized design lasting 78 days. The diets consisted of 30% U. decumbens hay and 70% concentrate, supplemented or not with Trichoderma longibrachiatum fungus (TL B13M2; 30 ml) or Rhodotorula mucilaginosa yeast (RM O166; 30 ml) isolates. In the first experiment, the CMCase and xylanase from Aspergillus terreus and T. longibrachiatum were more active and efficient (P < 0.05) than from yeasts. In the second experiment, the nutrient intake, digestibility, MP synthesis and body nitrogen retention were not influenced (P > 0.05) by fungal supplementation. Microbial efficiency was lower (P < 0.05) with the use of RM O166. The inclusion of TL B13M2 showed increased activity of CMCase and xylanase.