Nutritive Value of Mulato II Hybrid ('Brachiaria' spp) for Cattle: Effect of Cutting Interval on Chemical Composition and In Situ Rumen Degradability

The grass cultivar Mulato II ('Braichairia ruziziensis' x 'B. decumbens' x 'B. brizantha') was evaluated as a feed source for Cambodian cattle by chemical analysis and by the nylon bag in situ incubation technique. Evaluations were undertaken for periods of re-growth of 5, 7 and 9 weeks. Total forage yield increased (122, 216 and 233 kg DM/ha per week, respectively) as the period of regrowth increased, however nutritive value for cattle was compromised. Crude protein concentration in cut forage decreased from 9.6% to 6.7% DM and crude fibre concentration increased from 24.4% to 28.9% DM with increasing regrowth period (i.e. with advancing plant maturity). Irrespective of cutting interval, CP of leaf was always higher and CF lower than of stem, while the corresponding values for whole forage were intermediate. The effective organic matter degradability of Mulato II (assumed rumen turnover 0.04/h) decreased (0.56, 0.49 and 0.45 at 5, 7 and 9 weeks of re-growth, respectively) as period of regrowth increased. The mean washout fraction was highest for leaf (0.16) and lowest for stem (0.10), with whole forage being intermediate (0.13). Effective organic matter degradability was highest for leaf (0.54) and lowest for stem (0.45), with whole forage again being intermediate (0.51).