2.4. Blood sampling and laboratory analyses
At the end of experimental period, 12 birds from each treatment were randomly selected (2 birds per replicate). The blood was drawn from wing vein using sterilized needles and syringes in vacutainer tubes for serum collection. Feed was not withdrawn from the feeder before blood was collected. After the serum was separated naturally, it was centrifuged for 10 min (3000 × g) at room temperature. Serum was collected in tubes and stored at −20 °C until further analysis. Serum glucose, total cholesterol, total proteins, calcium, and phosphorus were measured spectrophotometrically by using commercial kits (Spectrum chemical company, Obour City – Cairo, Egypt).