Potential Use Of Selected Seaweeds As Feed Supplements On Growth Performance And Survival Of Nile Tilapia (Oreochromis Niloticus -Linnaeus, 1758) Fingerlings.

Abstract

Aquaculture contributes to food security, increases protein sources, creates employment and more importantly supplements the capture fisheries that is dwindling. Aquaculture production is positively associated with using quality seeds and feeds. Rapid aquaculture growth in many parts of Kenya has caused the rise in demand for quality fish feeds for the commonly cultured fish species. Thus, the need to investigate various locally available feed ingredients and realise their value in fish feeds. The study investigated the growth performance of Nile tilapia (Oreochromis niloticus) fingerling fed seaweed (Hypnea cornuta and Hypnea musciformis) supplemented diet, with freshwater shrimp (Caridina nilotica) as the protein ingredient. Three species of seaweeds (H. cornuta, H. musciformis and Ulva reticulata) were sampled and tested for their protein content. The results showed crude protein was highest in H. cornuta (22.4±0.07 mg/g) and H. musciformis (21.52±0.08 mg/g) as compared to U. reticulata (11.69±0.16 mg/g hence U. reticulata was dropped from experimental feed formulation. Five experimental diets containing 20% H. cornuta, 30% H. cornuta, 20% H. musciformis, 30% H. musciformis and the control diet which contained no seaweed were formulated. A total of 450 O. niloticus male fingerlings (mean weight ±1.42g) were obtained from Green Algae Farm, Sagana. The experiment was conducted at Chiromo campus for a duration of 60 days (2 months). The nutritive value of the test ingredients and experimental diets was determined using the Association of Official Analytical Chemist (AOAC) methods. The effect of the different experimental diets on final weight, specific growth rate (SGR), condition factor, feed conversion ratio (FCR) and survival was determined. O. niloticus fed on 20% H. cornuta recorded the highest weight gain (9.30±0.24g). Condition factor ranged from 1.21±0.05 to 1.84±0.03 and was above one in all the diets, indicating good fish health and culture conditions. The highest Specific Growth Rate (SGR) was on fingerlings fed 20% H. cornuta diet (3.27±0.03). Feed Conversion Ratio (FCR) was at 1.4 across all the diets indicating an optima FCR. The survival rate was 100% throughout the experiment duration. Therefore, this study suggests that 20% H. cornuta can be a supplement on O. niloticus fingerling diet since it performed slightly better on weight gain and, in other growth parameter aspects. 30% H. cornuta and H. musciformis supplements may not be recommended as supplements in O. niloticus fingerling diets. This information will benefit seaweed farmers, fish farmers, and fish feed producers searching for more species or feed ingredient to exploit.