FACTORS AFFECTING DEGRADATION OF BARLEY STRAW IN-SACCO AND MICROBIAL ACTIVITY IN THE RUMEN OF COWS FED FIBER-RICH DIETS III - THE AMOUNT OFSUPPLEMENTAL ENERGY

A basic diet composed of 76.2% untreated barley straw +23.8% grass hay was given to three non-lactating cows at 90% of ad libitum intake; th e diet was supplemented with fishmeal to make the ration up to 12% pro tein on dry matter basis, a mineral-vitamin mixture and either 1.5 kg; 3.0 kg or 4.5 kg of rolled barley/cow x day in a Latin Square design, The inclusion of rolled barley affected the degradability of DM, OM a nd individual components of the cell wall of barley straw incubated in nylon bags for up to 72 h. The higher the energy level of supplementa tion, the lower the digestion of the cell wall components. The amount of starch influenced rumen pH, ammonia and VFAs concentrations, ATP an d protozoal numbers, but no treatment effect could be detected upon th e outflow rate of liquid or particulate phases. The ATP and DNA concen trations found inside the nylon bags suggest the presence of an inacti ve or less active population towards the substrate after 24 h of incub ation. (C) 1998 Elsevier Science B.V.