Global Journal of Science Frontier Research, D: Agriculture and Veterinary, Volume 23 Issue 4

tilapia was regularly observed especially after feeding in the morning and in the evening to determine their conditions such as movement, infection, colorations and diseases. Sampling was continued until harvest. k) Final Harvesting Final harvesting of tilapia was done by draining each hapa completely on Oct 6, 2021. Weight of 20% population of stocked fry were measured using digital pocket weighing machine. Fish were counted and , their batch weight was recorded. l) Proximate Analysis of Experimental Diet Quadrant sampling of prepared diets was done to draw representatives for proximate analysis. Proximate analysis of each experimental diet was done at National Animal Nutrition Research Centre, Khumaltar, Lalitpur. Proximate composition (dry matter, crude fiber, crude protein, crude fat, total ash, gross energy cal/g) of four treatment diet was calculated. m) Water Quality Analysis Temperature, pH, and Dissolved oxygen (DO) were recorded in daily basis (6 am, 2 pm, 6 pm) in pond. Temperature and dissolve oxygen were measured by using dissolve oxygen meter (Hanna HI 9147 DO meter) and pH was measured by Hanna HI 98128. While ammonia, were measured fortnightly by using instrument called Hach Ammonia test kit of pond between 7:00 to 7:30 am. Five ml sample in the vial with the help of 5 ml syringe was taken and 1 drop Ammonia Reagent I in the Vial sample was added and shake. Then 3 drops of Ammonia Reagent II were added and finally the observed color was immediately compared with Ammonia color chart. Turbidity was measured fortnightly by Secchi disk. n) Economic Analysis Economic analysis was conducted to determine economic returns of the four treatments tested during the experiments. The economic analysis was based on the farm gate price for the harvested fish and current local market prices for the all-other inputs. The benefit cost ratios of the different treatments were calculated by using following formula; Total cost = ∑Cost of feeds+ labor cost Labor cost= Hapa preparation and installment Total Income = Total number of monosex fingerlings production × Price of monosex fingerlings (NRs/individuals) B: C ratio = (Total Income) ⁄ (Total Cost) The economic analysis was mainly based on farm gate price for the stocked and harvested fish and current local market prices for all other inputs in Nepal. o) Statistical Analysis The data was collected during the course of time and statistical analysis of data was carried out with Gen-Stat 15th edition. Effect of treatment was carried out using one-way analysis of variance (ANOVA), followed by a post hoc Duncan's multiple range tests. Differences were considered significant at the 95% confidence level (p<0.05). All means were given with ± standard error (S.E.). III. R esults and D iscussion a) Proximate Analysis of Experimental Diet Proximate analysis of experimental diet is shown in Table 3. Fresh Dry matter percentage was highest in 100% Soybean meal-based diet followed by 75% Soybean meal+ 25% Fishmeal, 50% Fishmeal + 50% Soybean meal and 100% Fishmeal. Fish meal- based diet had the highest crude protein (27.07%) than the other treatments. Highest ash percentage and crude protein was found in 100% Fishmeal. Similarly, Energy was highest in 75% Soybean meal followed by other treatments. Table 2: Proximate Analysis of Experimental Diets Constituents Fresh Dry Matter (%) Crude Protein (%) Ash (%) Crude fiber (%) Energy (cal/g) T 1 88.55 27.07 14.46 7.44 30961.9 T 2 88.64 26.9 10.04 5.57 40445.7 T 3 90.39 26.3 7.43 7.26 42195.3 T 4 91.29 26.3 4.89 6.72 40856.2 T1= control diet, Diet-1; T 2 = 50% replacement of fishmeal by soybean meal (SBM), Diet-2; T 3 = 75% replacement of fishmeal by soybean meal, Diet-3 and T 4 = 100% replacement of fishmeal by soybean meal, Diet-4. b) Growth Parameter A mean weight of about 0.1g size fry were stocked at the beginning of the experiment in all treatments which were not significantly different (p>0.05) with each other. The analysis of variance indicated that there was no significant difference in weight gain among T1, T2, T3 and lowest was found in T4. Up to 75% replacement, methionine is supplied by fishmeal. Replacement by soybean meal (100%) may have drastically reduced methionine content in diet. Insufficient dietary methionine reduced the growth performance and protein utilization (Sveier et al., 2001).Low growth in complete replaced fishmeal diet with soybean meal could also due to increase in carbohydrate component (Chou et al., 2004). Global Journal of Science Frontier Research ( D ) XXIII Issue IV Version I Year 2023 33 © 2023 Global Journals Replacement of Fish Meal with Soybean Meal on Growth Performance of Monosex Nile Tilapia ( Oreochromis Niloticus ) Fish Diet