Forage intake and nutrient digestibility of tropical grasses with or without supplementation of the two fermented organic wastes

Abstract

Three experiments were conducted with adult rams to determine the intake and in vivo digestibility of the dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) of native tropical grass hay (NTGH) and sorghum silage (SS) with or without supplementation of fermented wastes from a tilapia fish processing plant (FWTP) and fermented sludge from a tuna processing plant (FSTP). In the first metabolic trial, the two forages were compared without supplementation. Four adult native rams were assigned to treatments in a completely randomized design (CRD). Higher forage intake (P < 0.05) was observed in rams fed with NTGH than with SS. Apparent nutrient digestibility was also higher for NTGH than for SS, but these differences were not statistically significant. In the second and third metabolic trials, the effect of supplementation with FWTP and FSTP, respectively, at levels of 30% of expected DM consumption based on live weight, to basal diets of NTGH and SS, was evaluated. In both experiments, eight native rams were assigned to treatments in a CRD. The rams supplemented with both fermented fish by-products had higher (P < 0.05) DM and CP intakes than animals without supplementation, but a greater response was observed in those consuming NTGH rather than SS. Both supplements also tended to improve DM, CP and NDF digestibility in SS diets, whereas with NTGH diets supplements improved CP digestibility, and FSTP increased DM digestibility. The only negative effect observed in this diet was the decrease in the digestibility of NDF when supplemented with FSTP.