Effects of urea and saccharose on intake and digestion of a Digitaria decumbens hay by black belly sheep

Effects of incorporation of urea and saccharose in diets, on intake and digestion by sheep of a 35-day-old pangola (Digitaria decumbens) hay, have been studied according to a 4 X 4 Latin-square design. Sixteen rams were given four diets: hay (C); hay plus urea (U; 23 g/kg hay); hay plus saccharose (S, 60 g/kg hay), hay plus urea and saccharose (SU). Acid-detergent fibre and crude protein (CP) content of the roughage were 395 and 78 g/kg dry matter (DM) respectively Intake of hay (g DM per kg live weight(0.75)), supplemented with urea and sugar (42.9), was lower (P < 0.05) than with other diets (47.2, s.e. 1.6). The organic matter (OM) total tract and ruminal digestibility of the diet C, S, LS and SU were 0.622, 0.590, 0.625 and 0.587 (s.e. 0.007); 0.361, 0.380, 0.378 and 0.345 (s.e. 0.015) respectively. Effective degradation and nylon bag kinetics of DM degradation were higher with U and S compared with S or C. Few differences were observed between diets for ruminal concentration of volatile fatty acids. The ruminal ammonia concentrations were higher (P < 0.05) for the diets with urea than without urea (78 v. 215 mg/l). The efficiencies of the microbial synthesis (g nitrogen per kg OM fermented in the rumen) were, 23.6, 22.4, 24.9 and 29.3 (s.e, 1.7)for the diets C, U, S and SU respectively. Even though additional urea increased nitrogen availability for ruminal bacteria, urea supplementation did not affect significantly intake or digestion of the pangola hay of medium CP content used in this experiment.