Browsing by Author "Rajapakshe, A. D. W. R."

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    Effect of almond-based diet, on the growth performance and selected hematological parameters of Nile tilapia (Oreochromis niloticus) fingerlings
    (Faculty of Science, University of Kelaniya Sri Lanka, 2023) Gunawardana, M. P. P.; Parakrama, M. G. I. S.; Rajapakshe, A. D. W. R.; Weerasinghe, R.
    The inconsistency in supply, and high prices pose constraints on the utilization of fish meal, as the protein source, in the process of fish feed preparation. Therefore, it is crucial to identify costeffective alternative protein sources for fish feed formulation in aquaculture to overcome these limitations. To address this issue, tropical almond kernel meal has been identified as one of the alternative protein sources for replacing fish meal in the process. In the current investigation, four experimental meals i.e., Diet 1: prepared feed with 0% tropical almond kernel meal (TAM) (control feed), Diet 2, 3, and 4 replaced fish meal with TAM at 10%, 30%, and 50%, respectively, were used. Additionally, Diet 5 which was purchased commercially was also used as the second control feed. Effects of these replacements of fish meal with TAM were assessed by feeding these five experimental feeds separately to five treatments of all male Nile tilapia (Oreochromis niloticus) fingerlings, each with three replicates, and evaluated the growth performances, survival, and selected haematological parameters; total erythrocyte count, haemoglobin count, differential leucocyte count, and haematocrit calculation under laboratory conditions. Experimental feeds processed with TAM diets (Diet 2, Diet 3, Diet 4) contributed to the growth performances, survival, and haematological parameters of Nile tilapia fingerlings, and the results were significantly different (One-way ANOVA, P<0.05) from those of two control feeds (Diet 1 and Diet 5). The highest mean percentage weight gain (316.8±35.0), mean specific growth rate (2.036±0.12), and mean average daily growth (4.526±0.49), was achieved by the Diet 3 (30% TAM) when compared to other treatments. However, there was no significant difference in the mean percentage survival rate for five experimental diets. When considering feed conversion ratio, the lowest feed conversion ratio (FCR) (1.210±0.05) and the highest mean feed efficiency ratio (FER) values (0.827±0.03) were obtained from Diet 3 feed fed treatment. The highest FCR (2.675±0.04) value was obtained from the Diet 5 feed fed treatment. Among the various dietary options, Diet 3 fed fish displayed the highest values for red blood cells (RBCs) at 3.173×106 mm- 3 and hemoglobin (Hb) at 11.225 g/dL. These values were significantly different (P<0.05) from those values observed for the other experimental diets tested. The findings suggest that incorporating 30% tropical almond kernel meal into the fish feed as their diet can have a positive impact on both RBC count and Hb levels in O. niloticus fingerlings. The outcome of this study suggests that there is a definite potential for tropical almond kernel meal as a beneficial dietary component for enhancing blood parameters as well as growth parameters in O. niloticus. Further exploration is highly motivated due to the positive impact of the results.
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    Effect of dietary supplementation of probiotics and ascorbic acid on the growth, survival and haematological parameters, and enhancement of resistance to bacterial infections in Nile Tilapia (Oreochromis niloticus)
    (Faculty of Science, University of Kelaniya Sri Lanka, 2023) Nethmini, A. G. C.; Parakrama, M. G. I. S.; Rajapakshe, A. D. W. R.; Weerasinghe, R.
    This study was conducted to evaluate the effects of dietary administration of probiotic (PROFS POWER®) and ascorbic acid in Nile tilapia fingerlings (Oreochromis niloticus) diets. A total of 90 Nile tilapia fingerlings were distributed into three triplicate treatments. The first treatment, T1 was fed a balanced diet supplemented with probiotics (5 g/kg), whereas T2 received the same basal diet supplemented with ascorbic acid (500 mg/kg). Fish of the third treatment, T3 were served a control diet free from both probiotics and ascorbic acid. After three months of the experiment, survival and growth performances were evaluated and blood samples were collected from the experimental fish of different treatments. The protective effect of the two compounds was evaluated via a challenge infection test, using Aeromonas hydrophila. For the histopathological study, tissue specimens of the gills, liver, and intestine were excised from the tested fish. The specific growth rate (%) was significantly higher (p<0.05) in T1 (1.89 + 0.04) followed by T2 (1.88 + 0.04) compared to the control (1.62+ 0.04). The survival (%) was significantly higher (p<0.05) in T1 (93.33 + 3.33) and T2 (90.00 + 0.00) compared to the control (63.33+ 6.67) at the end of the feeding trials. Significant improvements (p<0.05) in hematological parameters of fish such as the mean erythrocyte count (RBC), white blood cell count (WBC), haemoglobin content (Hb) and haematocrit (Hct) were found with experimental groups, fed with probiotics and ascorbic acid compared to the control group. Haemoglobin content and RBC were significantly (p< 0.05) reduced in T3 after bacterial challenge, but fish in T1 and T2 were not significantly affected. The challenge infection showed an improved level of protection in fish fed with two supplemented treatments compared to the control. Gill hyperplasia was observed in the control treatment while almost normal gill structure was observed in fish fed with supplements. Melano-macrophage centers were observed in liver sections of fish in T1 and T2. Necrotic areas were observed in the gut sections of fish in the control treatment. The shown protection in fish in T1 and T2 may be due to the protective effect of supplemented diets. The results revealed a positive growth enhancement and improved level of protection of O. niloticus with the incorporation of both ascorbic acid and probiotics as growth promoters in their diet with respect to its growth, haematology, innate immunity, and disease resistance. Following the experimental design, adding 500 mg of ascorbic into one kilo of diet was cheaper than adding 5 g of probiotics. Therefore, it is suggested that the incorporation of ascorbic at a dose of 500 mg per one kilo of diet could be a potential, less expensive, and promising dietary supplementation than incorporating probiotics for Nile tilapia (O. niloticus) fingerlings aquaculture.