Abstract
Parturition and early lactation are considered as the most critical and stressful periods of dams life cycle because of high nutritional requirements for colostrums and milk production. This study aimed to evaluate the influence of physiological status on the blood metabolic profiles, colostrum, milk compositions and thyroid hormonal status of lactating ewes and their newborn in two sheep breeds (Naemi and Najdi) managed under an intensive system. Ten healthy ewes from each breed were selected at parturition. Blood samples, colostrums and milk samples were collected at parturition and 45 days later both from ewes and their newborns. Ewes were fed concentrate pellets with Rhodes grass for both breeds and kept under the same environmental conditions and management. Colostrum and milk samples were analyzed for nutrients composition. Blood serum of ewes and their newborns were analyzed for albumin, total protein, cholesterol, glucose, calcium (Ca), phosphorus (P), triiodothyroxine (T3) and thyroxine (T4). At parturition, a significantly higher glucose, Ca and P levels in blood serum were reported for ewes and newborns of Najdi compared with Naemi breed. At 45 days postpartum, a significantly lower Ca (p<0.001) and P (p<0.05) levels in blood serum of Najdi ewes and their lambs with significantly (p<0.05) higher T3 and T4 of ewes when compared with Naemi breed. Colostrum and milk fat and Lactose percentages of Naemi ewes were significantly higher (p<0.05) compared with Najdi breed. This study showed a breed variation in term of certain metabolic parameters and colostrum and milk composition during parturition and early lactation.