Role of Lemna Minor Feed Inclusion on Growth, Selected Reproductive Performance Parameters and Polyunsaturated Fatty Acids Levels of Oreochromis Niloticus

Abstract

Currently, standard fish feeds formulations use expensive and unsustainable animal and fish products as ingredients which also face competitive uses amongst humans and other animal feeds manufacturing industries. Minimal information exists on how Lemna minor inclusion in fish feed production affect growth, reproduction and Polyunsaturated Fatty Acids (PUFAs) bioaccumulation in tissues of Oreochromis niloticus, the largely cultured fresh water fish species in Kenya. Role of diets containing cultured L. minor on growth, reproductive performance and PUFA levels of O. niloticus were investigated. Cultured L. minor was used to formulate experimental diets at inclusion levels of 0% (control), 10%, 15%, 20%, and 25% followed by proximate analyses. The diets were tested on a completely randomized experimental design comprising 450 O. niloticus in fifteen 9m3 raised wooden box ponds each containing 30 fish (18 ± 1g), with a male to female ratio of 1:3 and cultured for 16 weeks at Kenya Marine Fisheries Research Institute -Kegati, Kisii County. Fish were fed twice daily at 10% body weight: at 9.00 a.m. and at 5.00 p.m. Water quality parameters of the culture environment were monitored using a YSI digital multi parameter probe. To evaluate fish growth performance parameters at the end of 12 weeks, fish length-weight measurements were done fortnightly using a measuring board and a Sartorius top pan weighing balance respectively. At week 14-16: eggs were collected from mouth brooding females and used to estimate fertilization, hatchability and survivability rates. Milt was extracted from gonads of mature males and used to evaluate sperm: concentration, % motility, and its duration of motility using an improved Neubauer chamber and a Leica microscope (Stereo 6050171) at a magnification of x400. Blood sera samples from mature males and mouth brooding females were used to determine testosterone, estradiol 17β and progesterone hormone profiles using Enzyme Linked Immunosorbent Assay. Gas Chromatography, mass spectrometry (GC MS) was conducted on the L. minor feeds and fish samples to establish their PUFA profiles