Protein requirements of Chios sheep during maintenance.

The requirements of non-lactating non-pregnant ewes for digestible nitrogen for maintaining nitrogen or weight equilibrium were studied using soybean meal or urea as the sources of supplemental nitrogen. From the nitrogen balance data, assuming nitrogen losses of .05 g N/kg -73, the digestible nitrogen requirement for maintaining nitrogen equilibrium was. 195 -+ .0237 and .188 + .0099 g N/kg.73 for soybean and urea as the sources of supplemental nitrogen, respectively. These estimates are close to the value of .20 g digestible nitrogen required for weight equilibrium obtained in the feeding trial. Increase in the levels of digestible nitrogen intake up to .370 and .450 g/kg.73 for soybean meal and urea, resulted in a linear increase of retained nitrogen. At higher levels of digestible nitrogen intake, retained nitrogen plateaued or declined with added soybean meal or urda. Addition of starch slightly increased the energy intake but tended to reduce crude fiber digestibility and reduced straw intake significantly. It also tended to reduce urinary nitrogen and increased retained nitrogen. (