Avaliaçao de dietas à base de cana-de-açúcar (Saccharum officinarum L.) e diferentes níveis de semente de algodao (Gossypium hirsutum L.)

It was used four ruminal fistulated cows, in 4x4 Latin square design, to study parameters related to bovine digestive process fed with diets conmposed, on dry matter (DM) basis, 66.3 percent of sugar cane and supplemented with 0, 10, 20 and 30 percent of whole cottonseed (WCS) with linter, in the treatments T0, Tl, T2 and T3, respectively, in replecement of cottonseed meal, that was fed in the proportion of 30 percent of dry matter. Dry matter and digestible energy intakes showed a quadratic effect of the treatments, with higher and lower intakes observed on Tl and T3, respectively. Diet nutrients digestibility showed quadratic effect for the ether extract; with higher digestibility on treatment T2, the nitrogen retention, as a percentagem of absorbed nitrogen, showed a tendency for quadratic effect. The rumen volum and rumen liquid phase turnover also showed a significant quadratic effect, with rumen fluids of treatments Tl and T3 renewed fast and slowly, respectively. The pH and ammonia values from rumen fluid showed a significant quadratic and linear effects, respectively, with the lowest average pH (7.02) observed on treatment T2 and the lowest ammonia average concentration (6.90mg/dl), on treatment T3. Total volatile fatty acids concentrations showed quadratic effect and the molar acetic acid percentage showed an linear increase, while butyric tended to decrease and propionic acid to continue steady with crescent WCS levels. There was a linear decrease on rumen protozoa numbers, and in the treatment T3, constituting only 30.66 percent of observed number on treatment T0.