In order to evaluate the in situ degradability of the dry matter and crude protein of silages of six sorghum genotipes in different stages of maturation, four fistulated crossbred holstein-zebu steers, fed with grass hay ad libitum, were utilized. The silage samples were dried and milled at 5 mm screen and 5 g of each sample were placed in 12 x 18 cm naylon bags and 50 µm porous size, and were introduced through the fistulas. After different times of incubation (6, 12, 24, 48, 72 and 96 hours later), the naylon bags were removed, the samples from the same genotipe, animal and time of incubation were transformed in a homogenous pool and milled at 1mm screen, and were stored for further analysis of DM and CP. It was used the split-split plot design in which the parcels were the silages of different genotipes, split-plots were the periods of harvesting and split-split-plots were the six periods of incubation. In this study, there were differences on dry matter and crude protein disappearance of the sorghum silages, although these can not be attributed to the percentage of grains in the different genotipes. The age of the plant influenced the effective degradability of digestible fractions, benefiting early stages.
crude protein; dry matter; in situ degradability; silage; sorghum
