Screening of Leaf Meals as Feed Supplements in the Culture of Oreochromis niloticus

Three leaf meals, Gliricidia sepium , cassava ( Manihot esculenta ), and Stylosanthes humilis were screened as feed supplements in the culture of the Nile Tilapia, Oreochromis niloticus . The experiment had four treatments. Treatment A had S. humilis leaf meal incorporated in the feed while treatment B had cassava leaf meal in the feed. Treatment C had Gliricidia leaf meal incorporated in the feed while treatment D was made up of feed formulated without leaf meal (control). Proximate analysis of these leaf meals showed that Cassava leaf meal had the highest crude protein content (26.3%) followed by Gliricidia leaf meal (22.9%) and Stylosanthes leaf meal (19.5%). All the four diets (A - D) were formulated with maize flour, soybean, fish meal, blood meal and the respective leaf meals and crude protein content ranged from 30.57 - 36.42 %. The diets were distributed randomly to twelve experimental units containing Oreochromis niloticus fingerlings with mean weight range of 2.40-2.55g and fed for twelve weeks. The feed containing cassava leaf meal (Treatment B) gave the best mean weight gain of 3.50 ± 0.01g followed by the feed with Gliricidia leaf meal with a mean weight gain of 2.21 ± 0.06g while the feed with Stylosanthes leaf meal and the control gave mean weight gains of 2.05 ± 0.25g and 1.06 ± 0.03g, respectively. Mean weight gain in treatment B (cassava leaves) was significantly higher (P < 0.05) than mean weight gain in other treatments. Mean growth rate ranged from 0.01 ± 0.006 g/day for the control treatment to 0.04 ± 0.001 for the fish fed Cassava leaf meal diet. Specific growth rate (SGR) was also highest in the treatment with cassava leaf meal (1.07 ± 0.11%/day) and lowest in the control. Protein efficiency ratio (PER) was 0.11 ± 0.004 in Treatment B, 0.07 ± 0.001 in Treatment C, 0.06 ± 0.009 in Treatment A and 0.03 ± 0.001 in the control. The food conversion ratio (FCR) was best with cassava leaf feed (3.71 ± 0.19) followed by Stylosanthes (5.51 ± 0.27), Glyricidia (6.17 ± 0.22) and the control (9.48 ± 0.58). FCR, SGR and PER for treatment B (cassava leaves) were significantly better (P < 0.05) than the values for other treatments. Percentage survival ranged from 92% with Stylosanthes to 100% with cassava leaf feed. The study showed that leaf meals can be effectively used in the diet of Oreochromis niloticus.