The effects of Moringa oleifera leaf meal and raw and cooked seed meal as a replacement for synthetic antibiotic (tetracycline) on carcass characteristics, heart and liver histology of broiler chickens were assessed in a 7-week feeding trial. The design of the study was a completely randomised design. There were 5 treatments: negative
control (D1), positive control (D2), treatments 3, 4 and 5 (D3, D4 and D5) contained 0.25 g/kg of feed of raw air-dried Moringa oleifera leaf meal, 0.25 g/kg of feed of raw air-dried and cooked airdried Moringa oleifera seed meal respectively. Each treatment had four replicates of 8 birds per replicate. The results of the study indicated no significant difference across the treatments for most of the carcass characteristics. Birds on D1 recorded the lowest mean values for heart (6.94 g), spleen (1.56 g), wings (121.00 g) and drumstick (154.24 g). Birds on D4 compared well with those on D2 in terms of drumstick, spleen, heart and wings. No visible lesions were observed in the heart histology of the experimental birds. Liver photomicrograph of birds on D1 indicated mild dissociation of hepatic cords, those on D2 showing closely-packed hepatic plates. Those on D3 showed a few foci of mild random single-cell hepatocellular necrosis. Those on D4 showing no visible lesions while those on D5 showed severe diffuse fatty change of hepatocytes with a few normal hepatocytes. Birds on raw Moringa oleifera seed meal compared well with those on synthetic antibiotics, however, the liver histology of those on synthetic antibiotics indicated potential danger of liver damage.