The chemical composition, crude protein fractions (A, B1, B2, B3 and C) and total carbohydrate fractions (A, B1, B2 and C), and respective degradation rate of B1, B2 and B3 protein fractions and A + B1 and B2 carbohydrate fractions of Tifton 85 bermudagrass hay from plants harvested with 28, 35, 42 and 56 days of regrowth, fertilized with 75 kg/ha/cut of N, were evaluated. The protein content of hays from 28 to 56 days of regrowth ranged from 17.58 to 12.58%. The values of A, B1, B2, B3 and C protein fractions presented between 22.1 and 35.53%; 0.24 and 4.55%; 30.37 and 31.34%; 26.55 and 36.62%, and, 5.75 and 6.76%, respectively, as a percentage of the total crude protein, in the hays with ages between 28 and 56 days of regrowth. The degradation rate of B1, B2 and B3 protein fractions presented between 0.319 and 1.324; 0.0724 and 0.0936, and, 0.0077 and 0.012 h -1, respectively, in the hays with ages between 28 and 56 days of regrowth. The total carbohydrates content ranged from 72.98 to 78.77%, for the hays with 28 to 56 days of age. The values of A, B1, B2 and C carbohydrate fractions presented between 2.73 and 5.44%; 1.91 and 2.35%; 77.49 and 80.59%, and, 13.59 and 17.87%, as a percentage of total carbohydrates, in hays with ages between 28 and 56 days of regrowth. The degradation rate of the A + B1 and B2 carbohydrate fractions presented between 0.181 and 0.20, and 0.04 and 0.0466 h -1, in hays with ages between 28 and 56 days of regrowth, respectively.
lignin; neutral detergent fiber; nitrogen compounds; starch; sugars
