The suitability of different mixtures of soybean meal (SBM), cottonseed meal (CSM) and groundnut cake (GNC) as ingredients to replace fish meal in the diets of Nile tilapia (Oreochromis niloticus L.), was evaluated over a 56-day growth period. Nine isonitrogenous (320 g.kg-1), isolipidic (100 g.kg-1) and isoenergetic (18 KJ.g-1) test diets were formulated in which different mixture combinations of SBM, CSM and GNC proteins replaced fish meal (FM) protein at levels of 50% and 75%. The control diet had FM as the sole protein source. Fish were fed at 6-4% body weight per day. The growth experiment was conducted in plastic tanks in a recirculation system. Each dietary treatment was in triplicate. Growth performance and feed utilization of fish fed with the oilseed meal mixtures indicated that up to 50% replacement could be more effective than a single source for the substitution of fish meal in tilapia diets. This was particularly evident with the diet containing equal proportions of all oilseed meals (EQ50). Combination of oilseed meals in different proportions was more effective than the single individual sources. This could be due to a compensatory effect which led to some reduction of antinutritional factors coupled with improved essential amino acid profile in the diet as a result of mixing.

Growing mixed-sex Nile tilapia, Oreochromis niloticus in earthen ponds to table size is a major challenge due to its early maturity and prolific breeding. This study determined the effects of two medicinal plants; Aspilia plant, Aspilia mossambicensis and Neem tree, Azadirachta indica on hatchlings production, growth performance, feed utilization, survival and haematology of O. niloticus. Experimental diets were prepared by adding 1.0, 2.0, 4.0 and 8.0 g of either A. mossambicensis or A. indica leaf powders into a kg of the control diet subsequently administered daily to twenty triplicates of O. niloticus for three months. Both A. mossambicensis and A. indica leaf powder at the used doses, reduced significantly hatchlings production of O. niloticus when compared to the control (P < .05). The lowest value of hatchlings count was found in A. indica dose 8.0 g kg−1 (P < .05). The use of A. mossambicensis leaf powder at a dose of 4.0 g kg−1 improved significantly growth performance and feed utilization (P < .05). In contrast, survival rate was not affected significantly by the two plants (P > .05). Both plants differentially increased significantly haematological parameters such as Hb concentration, packed cell volume (PCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), white blood cells (WBC), monocyte and lymphocytes while reduced significantly neutrophils and eosinophils (P < .05). In conclusion, A. mossambicensis and A. indica leaf powders control prolific breeding of O. niloticus, modulate its growth performance and feed utilization. The two plants also modulate haematological parameters of O. niloticus indicating immunological response towards stress or intoxication, however, the values obtained were not beyond the recommended range for healthy fish.

ABSTRACT:The nutritional suitability and cost effectiveness of cottonseed meal (CSM) as protein source in the diet of Nile tilapia (Oreochromis niloticus L.) with mean initial weight 4.24±0.20 g, was evaluated over a 56-day growth period. Four isonitrogenous (320 g kg -1 ), isolipidic (100 g kg -1 ) and isoenergetic (18 KJ g -1 ) test diets were formulated in which CSM protein replaced fish meal (FM) protein at levels of 0% (control), 25%, 50% and 75%. The control diet had FM as the sole protein source. The growth experiment was conducted in plastic tanks in a recirculation system each dietary treatment was in triplicate. After 56 days of feeding fish at 6% -4% body weight per day, CSM protein replacements of 25% and 50% did not significantly (P<0.05) affect growth (Specific Growth Rate, Weight Gain) and feed utilization (Feed Intake, Feed Conversion Ratio, Protein Efficiency Ratio, Apparent Net Protein Utilization and Energy Retention). However, the highest replacement level (75%) significantly reduced these parameters compared to the control diet and this was attributed to low levels of lysine, methionine and threonine and also to high levels of gossypol, trypsin inhibitors saponin and phytic acid in the diet. In terms of cost effectiveness, all the CSM based diets were more profitable than the control. The study indicated that CSM could replace at least 50% of fish meal protein in the diet of O. niloticus without adversely affecting growth and feed utilization and the most cost effective diet was also the diet with 50% inclusion level of CSM. @JASEM

The use of medicinal plants to control reproduction in aquaculture have recently received considerable attention because they are biodegradable, safe, effective and locally available. However, information on their effects on gonadal characteristics and histological features in fish is currently limited. The present study evaluated the gonadal characteristics and histological changes of Nile tilapia, Oreochromis niloticus gonads fed on Aspilia plant, Aspilia mossambicensis and Neem tree, Azadirachta indica. Juvenile fish were fed diets supplemented with four doses (1.0, 2.0, 4.0 and 8.0 g/kg diet) of A. mossambicensis or A. indica leaf powders at 3% of their body weight daily for 90 days to examine absolute fecundity (AF), relative fecundity, gonadosomatic index (GSI) and histology of gonads. The antifertility phytocompounds in the two plants were quantified by using standard methods. Results indicated that, all doses of A. indica and A. mossambicensis used reduced significantly AF and GSI values (p < 0.05). Dose-dependent histological alterations of gonads were noticed in both plants starting from doses of 2.0 g/kg in males and 4.0 g/kg in females. The highest percentages of total flavonoids (23.7%) and alkaloids (14.2%) were obtained from A. indica ethanol extract (p < 0.05). Taken together, dietary supplementation with A. mossambicensis and A. indica leaf powders alter gonadal characteristics of O. niloticus and histology triggered by alkaloids and flavonoids. Farmersinterested in using the two plants to control prolific breeding should limit the dose inclusion to 2 g/kg to avoid severe effects on fish testis and ovaries.

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