EFFECT OF SEASONAL-VARIATIONS ON SOME NUTRITIONAL AND PHYSIOLOGICAL-PARAMETERS OF EGYPTIAN SHEEP

The effect of seasonal variations on feed and water consumption, nutrients digestibility, nutritive value, N-balance, certain ruminal and physiological parameters and thyroid activity were studied in Egyptian sheep. Two feeding groups were designed. In each group 4 metabolism trials (1 trial in each season) were carried out using 3 fistulated local rams. Rams of group 1 were fed restricted ration (RFG) containing 65\% concentrate mixture and 35\% wheat straw to cover their maintenance requirements of DCP and SE. Rams of group 2 were fed the same concentrate mixture to cover their maintenance requirements of DCP. Wheat straw was offered ad lib. (AFG). Intake of ration and wheat straw was not significantly affected by seasonal variations in RFG. The same trend was observed for ration intake in A FG, hut wheat straw intake was significantly highest in spring and winter. The microbial protein synthesis was significantly lower in summer than in other seasons in the 2 groups. This was accompanied by an increase in ruminal ammonia-N. Thyroid hormones (T-3 and T-4) concentrations were significantly highest in autumn and the lowest in summer in RU:CI group. The same trend was observed in AFG without significant differences in T-4 concentrations. The digestibility and nutritive values of TDN, SC and DCP were highest in summer, and they were lowest in spring in RFG group. Daily feed units intake and N-balance per kg W-0.75 were not significantly affected by seasonal variations. The same trend was observed for rumen and rectal temperature and pulse rate. Skin temperature and respiration rate were significantly higher in summer than in other seasons of both the groups. The results showed that year round continuous ration allowances could not satisfy the animal energy requirements, especially, during spring, winter and autumn. Therefore it would be appropriate to re-evaluate different rations and make them suitable for different seasons.