This study was conducted to determine changes in some biochemical parameters reflecting the energy and protein metabolism status during lactation and dry period in Ouled Djellal ewes. The study was conducted on thirty clinically healthy ewes aged between two to four years. Blood samples were collected during three periods: the first week of lactation (early lactation); the 8th week of lactation (mid lactation) and three weeks after drying off. Plasma glucose concentrations on dry period were higher than those lactation (P<0, 05). The same parameter was higher in early lactation than in mid lactation (P<0,001). The highest cholesterol concentrations were recorded on dry period compared to lactation (P<0, 02). Similarly total protein levels in dry period were higher than those of lactation period (P<0,001). A decrease in plasma albumin levels were recorded in dry period and on early lactation compared to those obtained on mid lactation (P<0,001). The plasma urea concentrations on dry period were lower than those recorded on the 1st and 8th week of lactation (P<0, 006). creatinine concentration on mid lactation were higher, than those of early lactation and dry period (P<0,001). Current findings showed marked changes in certain biochemical parameters in Ouled Djellal ewes between lactation and dry periods. Several studies have demonstrated the impact of factors such as breed, season, feed, and experimental conditions on changes in blood biochemical parameters in sheep. All these factors could explain the differences observed between our results and those reported by other authors.
