Haematological responses of Nile tilapia (Oreochromis niloticus) to diets supplemented with varying levels of plant leaf meals

Abstract

Plant leaf meals have the potential to replace fishmeal in fish feed formulation, hence reducing its cost and increasing fish production. This study evaluated the effects of plant leaf meals (PLMs) on haematological parameters in Nile tilapia (Oreochromis niloticus). The PLMs of cassava, sweet potatoes, cowpeas and common beans were substituted at the rate of 100% (mixed leaves of all four species, Diet 5), followed by each separate leaf meal at 100% (Diet 4), 75% (Diet 3), 50% (Diet 2) and 0% (control diet containing fish meal, Diet 1). Fish collected from Mbegani Fisheries Institute were kept in five, 80 L capacity glass aquaria for 42 days. After every two weeks, blood samples were collected in heparinized capillaries and analysed. The red blood cells (RBCs) count, haemoglobin (Hb), packed cell volume (PCV), mean cell haemoglobin concentration (MCHC), mean cell haemoglobin (MCH) and mean cell volume (MCV) values decreased significantly (p ˂ 0.01) in fish as the inclusion level of PLMs was increased in the diet. After 28 and 42 days, the Hb, PCV and MCHC had significantly (p < 0.01) declined for fish fed with Diet 3, 4 and 5. Results from this study therefore suggest that the four PLMs are potential ingredients in fish feed formulation at lower inclusion levels up to 50%.