Effect of Melatonin on Some Hematological Parameters and Immune Status of Broiler Chicks

received no specific grant from any funding agency. Melatonin, the pineal gland hormone, has been shown to play a principle role in maintenance of health and well being of man and animals in all stages of life. The aim of the present study was to investigate the effect of melatonin on some hematological parameters and immune status of broiler chicks. For this purpose sixty-four, three weeks-old chicks of Hubbard strain weighing 500-633g were used. Birds were kept on lighting regimen of 12 hours natural light to 12 hours darkness. Chicks were randomly allocated into four equal groups of 16 birds each. The first group was kept as a control group and fed starter ration sprayed with ethanol saline without melatonin from the 4th to 8th weeks of age. The second, third and fourth groups were fed on the starter ration sprayed with ethanol saline containing 20, 30 and 40 mg melatonin / kg ration, respectively from the 4th to 8th weeks of age. Blood samples were obtained from the tibial vein of all birds at the end of the 1st week of treatment and then every week up to the end of the experiment. The obtained blood were used for determination of red blood cells (RBCs) count, hemoglobin (Hb) concentration, packed cell volume (PCV) as well as total and differential leukocytic count. Tissue samples from liver, spleen, thymus and bursa of Fabricious were taken for histopathological examination