NUTRITIONAL CONTENT OF FORMULATED FEEDS AND IN-SITU BASED FEEDS OF AQUACULTURE FISH IN THE WINAM GULF OF LAKE VICTORIA, KENYA

Abstract

The uses of feeds are critical to success of aquaculture farming on Lake Victoria Basin. The composition of the feeds can either be derived from in situ plants or animals i.e. the lake shrimp or omena within the ecosystem of Lake Victoria or externally sourced from outside the Lake i.e. imported formulated fish feeds. The net effect from the input of those feeds from outside could increase eutrophication within the lake while feeds derived from fauna and flora from the lake may not impact as negatively. The nutritional values of the feeds and the potentials of the feeds derived from outside the Lake and those utilizing local flora and fauna within the ecosystem of the lake are compared. The consequences of nutritional level from the different sources on the quality of fish product were estimated. Samples from both the formulated and in-situ based fish feeds were collected from aquaculture farms or from local sources around the Lake area. The samples were then freeze-dried and ground to fine local powder and dissolved using acid digest process. The resulting sample-acid solution was then analyzed using an Agilent 7500cx inductively -coupled plasma mass spectrometer (ICP-MS). With the exception of Arsenic (As), Barium (Ba) and Tin (Sn) wild fish muscle had significantly high PTEs in Silver (Ag), Chromium (Cr), Lithium (Li), Aluminium (Al), Cadmium (Cd), Mercury (Hg) and Lead (Pb) and also high in trace element concentrations in boron (B) and selenium (Se) compared to the caged fish muscle. Cadmium (Cd) and lead (Pb) contents in caged and wild fish samples were all below the FAO/WHO recommended limits. This study also showed that the differences were not quite discernable and that the data indicated are important preliminary findings that indicate that the differences in concentrations of micronutrients were wider than the differences in the concentrations of the macronutrients of the omena and lake shrimps of both closed and open lakes. The potentials of sustainable production of aquaculture especially caged culture from Lake Victoria is presented taking into account the optimal ratios measured in both formulated and in-situ based feed and their possible impact both economically and environmentally. Our study therefore; presents an environmentally sustainable means of solving food insecurity among the rapidly growing human population that suffers malnutrition, hunger, joblessness and disease