<b>Chemical composition and ruminal degradation kinetic of <em>Cynodon</em> grasses in different cut age</b>- DOI: 10.4025/actascianimsci.v27i2.1221

Abstract

The objectives of the experiment were to estimate the chemical composition, to estimate the metabolically energy, dry matter in vitro digestibility (DMIVD), organic matter in vitro digestibility (OMIVD) through an artificial rumen developed by Ankom and also dry matter in situ degradability (DMISD) of three Cynodon grasses (Tifton 85, Tifton 44 and Coast-cross) collected at the ages of 21, 42 and 63 days in the summer. Three cows with ruminal fistula were used to determine the in situ degradability. The following incubation times were 96, 48, 12, 6, 0 hours. However, the zero time was determinate through of washing with water in washing machine. The experimental design was a split-plot (plots like grasses and sub-plots like age of cut) with three repetitions. The cut age factor was evaluated by regression and the models were chosen based on the analysis of identity. The neutral detergent fiber and acid detergent fiber increased with harvest age (P < 0.05). However, the crude protein, metabolically energy estimated through mathematical equations, DMIVD and OMIVD decrease as harvesting age increased. The soluble fraction (a) showed reduction (P < 0.05) with age only for the DM. Cultivars and cut age did not effect (P > 0.05) the rate of degradation (c) of DM. The effective degradability of DM with passage rates of 2, 5 and 8%/h were not affected (P < 0.05) by the harvesting age