Factors affecting in situ dry matter degradability of tropical forage:: II.: Initial washing sample

Samples of milled to 5mm alfalfa (Medicago sativa L.), braquiaria (Brachiaria decumbens Stapf.), coast-cross (Cynodon dactylon x Cynodon nlemfuensis), jaragua (Hyparrehnia rufa Ness.) and braquiaria cut to 15mm were incubated in nylon bags for 6, 24 and 96 hours in rumen of three fistulated steers. The 5g samples in the bugs were treated in two ways: not washed as usual and washed for 15 min prior to insertion into the rumen. The objective was to study how the washing procedure could affect the parameters estimates in the in situ dry matter degradability equation, DMD=A-B.e(-ct). The potential degradation values (A) for washed alfalfa, coast-cross and jaragua were lower than those corresponding to not washed samples, The same parameter value was greater for washed 5mm braquiaria. When alfalfa, jaragua and coast-cross were washed, degradation rate (C) values increased whereas for 5 and 15mm braquiaria a decrease was observed. The results showed that the initial washing procedure may affect the parameters "A" and "C" according to the characteristics of forage, and therefore should be avoided.