School of Natural Resources and Environmental Studies

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Author: search.filters.author.Okoth, Elijah Oyoo

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    Combined effects of photoperiod and temperature on growth and survival of African catfish (Clarias gariepinus, Burchell 1822) larvae under laboratory conditions
    (Taylor and Francis, 2016) Okoth, Elijah Oyoo; Orina, Paul Sagwe; Rasowo, Joseph; Musa, Safina; Munguti, Jonathan M.; Karisa, Harrison Charo
    The effect of photoperiod (24L:00D, 12L:12D, and 00L:24D) and temperature (22 ± 1°C and 28 ± 1°C) on performance of Clarias gariepinus larvae was tested. Larvae weighing 3.2 ± 0.24 mg were cultured in aquaria at a stocking density of 20 fish L−1 and fed twice a day on catfish starter diet (40% CP) at 10 % BW day−1. Highest mean weight gain (31.00 mg), SGR (7.56% day−1), and survival (83%) were achieved at photoperiod and temperature combination of 00L:24D and 28 ± 1°C. Percent survival of larvae differed significantly (p < .05) among treatments with optimal survival of (83%) in treatment combination of 28 ± 1°C and 00L:24D, while lowest survival (40%) in treatment combination of 22 ± 1°C and 24L:00D.
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    Effects of dietary levels of essential oil (EO) extract from bitter lemon (Citrus limon) fruit peels on growth, biochemical, haemato-immunological parameters and disease resistance in Juvenile Labeo victorianus fingerlings challenged with Aeromonas hydrophila
    (John Wiley & Sons Ltd, 2016-04) Okoth, Elijah Oyoo; Muchiri, Mucai; Ngugi, Charles C.
    Essential oils (EOs) are used in the food industry because of their biological activity. We evaluated the effects of administration of essential oil (EO) extracted from bitter lemon (Citrus limon) fruit peels on the growth performance, biochemical, haemato-immunological parameters and possible disease resistance in fingerlings (4 weeks old) Labeo victorianus challenged with Aeromonas hydrophila. Fish were divided into five groups and fed diets supplemented with C. limon fruit peels EO extract at 1%, 2%, 5% and 8% [as fed basis] and treatment compared with control group fed diet without C. limon fruit peels EO extract. The experiment was executed in triplicate. Concentration of plasma cortisol, glucose, triglyceride and cholesterol decreased while that of total protein and albumin increased as dietary inclusion of the EO extract of C. limon fruit peels was increased from 2% to 5%. Meanwhile haemato-immunological parameters including red blood cell (RBC), white blood cell (WBC) counts, haematocrit (Htc), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC) and neutrophiles increased with increasing dietary inclusion from 1% to 5% inclusion of C. limon fruit peels EO extract. Serum immunoglobulins, lysozyme activity and respiratory burst increased with increasing dietary levels up to 5% inclusion of EO extract of C. limon fruit peels. We demonstrate that formulation of feeds by incorporating upto 5% the EO extract from C. limon fruit peels significantly improved biochemical, haematological and immunological response in juvenile fish resulting to lower mortality than the untreated groups and appear to be effective antibacterial against A. hydrophila.
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    Species Richness and Abundance of Birds in and Around Nimule National Park, South Sudan
    (The science publisher, 2016) Okoth, Elijah Oyoo; Simon, Gift Sarafadin
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    Characterization of the nutritional quality of amaranth leaf protein concentrates and suitability of fish meal replacement in Nile tilapia feeds
    (Elsevier, 2017) Okoth, Elijah Oyoo; Ngugi, Charles C.; Manyala, Julius O.; Fitzsimmons, Kevin; Kimotho, Ann
    A number of leafy vegetables,their protein concentrates and hydrolasates are under evaluation as alternative protein ingredients to fish meal(FM)in aqua feeds. This study evaluated the nutritional characteristics and suitability of replacing FM with the amaranth (Amaranthus hybridus)leaf protein concentrates (ALPC) as a protein ingredient in the diet of Nile tilapia (Oreochromis niloticus). Experimental diets were formulated, where 100%, 75%, 50%, 40%, 20% and 0% FM protein was substituted by protein from ALPC. The six dietary treatments were tested in triplicate in static flow-through tanks. The substitution effects were compared in terms of fish growth performance, nutrient utilization, whole body composition and apparent nutrient digestibility. After 160 days of feeding, the growth, nutrient utilization and Feed Conversion Ratio (FCR) in fish fed diets containing 100%, 75%, 50%, 40% and 20% FM were better (P < 0.05) than those fed diet with 0% FM. The Apparent nutrient digestibility was high for protein, lipid and energy and differed significantly among the dietary treatments (P < 0.05). Protein digestibility in fish was highest in feed formulated with 100%, 75%, 50% and 40% FM, which were significantly (P < 0.05) higher than at 25% and 0% FM. Lipid digestibility was comparable for all the diets except fish fed 0% FM. Digestible carbohydrates and dry matter were similar for all dietary treatments (P < 0.05). We demonstrate that it is possible to replace up to 80% of fish meal with ALPC without compromising the performance O. niloticus. These results demonstrate that although it is possible to replace large part of fish meal with ALPC, it is not possible to eliminate it in Nile tilapia diet as alternative protein ingredient
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