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Articles by L.C. Nwanna
Total Records ( 3 ) for L.C. Nwanna
  C.N. Anyanwu , L.C. Nwanna , O.A. Bello Olusoji and D.I. Osuigwe
  The poor nature of most agricultural processing practices in Nigeria have had adverse effect on our environment and the aquatic habitat are of no exception. This study was conducted to ascertain the median lethal concentration of the effluent within the 96 hours period and the histological damage on the liver and gills of Clarias gariepinus juveniles. Juveniles of the C. gariepinus (mean weight 30±2.5 g) were exposed to 87.5, 88.0, 88.5, 89.0, 89.5 and 90.0 mL of the locust bean (Parkia biglobosa) mill effluent under the standard laboratory conditions. Data on mortality corresponding to the various concentrations were subjected to the probit and logit transformations and used to calculate the LC50 graphically. The result shows the toxicity of the locust bean effluent to C. gariepinus juveniles as 0.089 mg L-1 (treatment 4) during the period of study. The results obtained on water physical chemistry shows that there were no significant difference between the controlled and the treated media nor between the treatments because values obtained fall within the accepted water quality standard for fish culture. Exposure to the effluent resulted in a number of physiological dysfunction of the test fish, such as rupture and erosion of the gills, leading to reduction in the respiratory surface area of the filament, that can cause the death of the fish as well as impairment of oxygen-carbon dioxide exchange. Observation of the fish under the tests revealed unbalanced swimming patterns, loss of reflex, rapid opercular movements and gasping for air. Histopathological examination of the gill and liver of the treated fish showed signs of damage, ranging from hypoxia, lesions, necrosis, fibrosis, cell stasis and hyperplasia.
  L.C. Nwanna
  Fish nutrition researchers often feed fishes at between 3-5% of their body weight daily. Environmental risks associated with excess feed leachate are so enormous in tropical waters leading to algal bloom which can toxify the aquaculture products and threaten their safety. Considering that feed requirements by fishes depend on a number of factors such as size, health status and the general condition of the culture environment; there is every need for the determination of the actual feed desired to meet their physiological needs, promote growth and reproduction based on peculiar conditions. This study was conducted to determine the appropriate feeding rate for tilapia, Oreochromis niloticus and consequential changes in the water quality. A 30% crude protein diet was fed to triplicate groups of O. niloticus fingerlings (10.13±0.58g) in glass tanks (75x45x40 cm) (20 fish/tank) at 2, 3, 4 and 5% body weight daily. The holding tanks were cleaned every two days after measuring the water quality parameters, pH, temperature and the dissolved oxygen. Results of the experiment indicated that the weight gain (WG, %) and specific growth rate (SGR) of the fishes fed at 3, 4 and 5% body weights were similar (p>0.05) but differed significantly (p<0.05) from the WG and SGR of the group of fishes fed at 2% body weight. However, there were no significant differences in FCR and PER of fishes fed at the various body weights. While the pH and the temperature of the culture media were not affected by the treatments, the dissolved oxygen was marginally lower in tanks fed at 4 and 5% body weights than in those fed at 2 and 3% body weights. The study established the optimum feeding rate for O. niloticus at 3% body weight daily, and the tendency for water quality deterioration with higher feeding rates.
  L.C. Nwanna
  Feeding trials and digestibility studies were conducted in recirculatory systems to assess the effect of replacing fish meal with 0, 5, 10, 20, 30 and 40% fermented shrimp head waste meal (FSHM) in practical diets for African catfish Clarias gariepinus. The different levels of FSHM were mixed with other ingredients to formulate 40% protein diets (Diets 1-6). The diets were fed to fingerlings of C. gariepinus (12.0± 0.03g) at 3% body weight per day for 84 days. The effect of the diets on the growth, carcass and mineral compositions of the fishes were evaluated. Results showed no significant variation (p>0.05) in apparent digestibility coefficient (ADC) of nutrients ADCprotein and ADCenergy, protein efficiency ratio (PER), food conversion ratio (FCR) and hepasomatic index of the fishes fed all the diets. However, the fishes fed diets (1-5) had similar (p>0.05) mean weight gain (MWG) and specific growth rate (SGR), which differed significantly (p<0.05) from the MWG and SGR of the group of fishes fed diet 6. Carcass yield and mineral depositions differed marginally in the fishes fed the various diets. Comparative costs analyses indicated that the best profit margin would be realized by replacing fish meal with 30% FSHM in the diet of the fish.
 
 
 
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