RESUMO
This experiment aimed to investigate the effects of substituting barley grain with discarded dates on intake and digestibility, nitrogen (N) utilization and fermentation characteristics of sheep fed Atriplex hay-based diets. Four Barki sheep (50.9 ± 2.93 kg of body weight (BW)) fitted with rumen cannula were used in a 4 × 4 Latin Square design with 23-day periods. Four isonitrogenous (~140 g crude protein (CP)/kg of dry matter (DM)) experimental diets were formulated with Atriplex hay, and dietary sugar content was increased by replacing barley grain with discarded dates (the proportions of discarded dates in the diet were 0, 93, 187 and 280 g/kg DM). Nutrient intakes were not influenced by diet. Organic matter, CP and neutral detergent fibre digestibility increased (p < 0.05) linearly and DM digestibility tended to increase with increased dates inclusion. Ruminal pH and molar proportion of butyrate increased (p < 0.05) linearly with increasing levels of dates inclusion, whereas ruminal ammonia-N decreased (p < 0.05) linearly. Total volatile fatty acid concentration was unaffected. Microbial protein synthesis (MCP) increased linearly and efficiency of microbial protein synthesis tended to increase as discarded dates increased. Total N intake was not affected by diets whereas, urinary N, urea-N and total N execrations linearly decreased (p < 0.05) with higher amounts of dates in the diets. Blood urea-N tended to decrease with increasing levels of dates. It could be concluded that replacing 100% barley grain with discarded dates as a source of soluble carbohydrates can enhance the utilization of N in Atriplex hay-based diet and consequently improve digestibility and MCP.