Consumo e digestibilidade de diferentes suplementos na transição secas-águas

Abstract

Brazil have a great potentgial in the world beef production in pasture systems, and this reflects its territorial extension and tropical climate. However, the production cycle in extensive regimes is complex, with the need for management of several factors. Supplementation is one of the factors used to circumvent this factor. To evaluate the consumption of different supplements and the relation with pasture consumption, five different commercial supplements (two mineral, two protein and one protein-energy) were fed to cattle averaging 520 (± 35) kg, provided with permanent rumen cannulas, and randomly distributed in a 5x5 latin square design, in individual pastures of Urochloa brizantha, cv. Marandu (Syn Brachiaria), receiving daily supplementation in the morning period, following the amounts (%BW) indicated on the product label (SP1=0.04; SP2=0.08; SP3=0.13; SP4=0.25; SP5=0.11). In total, the experiment was segmented into five periods of 12 days duration, with accounting for leftovers done daily and readjustment every 3 days. For forage availability estimation and collection, a 0.25 m² metal square was used. The collected samples were weighed to determine the natural matter content and were dried in a forced ventilation oven at 60°C for determination of dry matter (DM: method 930.15), crude protein (CP: Nx6.25; method 984.13) according to AOAC (1991) methodologies. The contents of acid detergent fiber (ADF) and neutral detergent fiber (NDF), as described by Van Soest and Robertson (1999); adapted by Mertens (2002). The TDN content was estimated from the NDF content as described by Capelle et al. (2001). The data obtained were submitted to SAS (Version 9.1.3, SAS Institute, Cary, NC 2004), verifying the normality of residuals and homogeneity of variances by PROC MIXED. There was no significant difference (P>0.05) in pasture consumption due to low forage availability. The supplement with the highest TDN content (640g/Kg) caused the highest intake and protein digestibility among all others. The quality and availability of forage are determining factors in the consumption of mineral, protein and protein-energy supplements.