Abstract

The  objective  of  this  work  was  to  evaluate  the  potential  and  effective  in  situ degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber of barley ( Hordeum vulgare L.) in Cutting ages: 130, 150 and 170 days. Bovine males of the Brown swiss breed, fistulated in the rumen, with ages of 3 years, and average weight of 435kg were used. The experiment was carried out in completely randomized block design (3 animals), with a factorial arrangementm of 3 x 6 (cutting ages and incubation times). The barley according to the cut ages were weighed in nylon sacks and incubated all at once and removed at the times of 0, 6, 12, 24, 48 and 72 hours, after incubation. Cutting age, incubation time and interactions between age and incubation time influenced the rumen degradability of DM, CP, NDF and FDA, except for the CP that there was no significant interaction between age and time. The analysis of variance of the regression did not reveal an effect of the cutoff age on the potential or effective degradability of the MS in the pass rates of 2, 5 and 8%/hour. The constant degradation rates “c” of the CP(3.00, 6.33,6.33 %/h, respectively), NDF (2.80, 2.77, 3.39%/h) and ADF (3.01, 3.02, 3.35%/h) were low. The potential degradability’s of the DM (86.71, 90.27, 82.83%), CP( 89.48,77.69, 82.15% ), NDF (85.21, 72.81, 81.18% ) and ADF (86.41, 70.33, 80.76%) were high, with models of quadratic type regression; as well as the effective degradability of the PC at the passage rate of 5%/h (66.04, 66.21, 69.54 %), NDF (56.09,51.10, 58.60%) and ADF (58.26, 50.23, 54.07%). Due to the higher soluble fractions and high effective degradability’s of CP in the three cut ages evaluated, this species can be classified as having a good nutritional quality

Keywords

potential degradability, effective degradability, incubation time, rate of passage