School of Natural Resources and Environmental Studies
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Item Macroinvertebrate metrics and lipid profiles as potential indicators of land use influence in a high altitude tropical highland stream (Sagana River Basin, Kenya)(Elsevier, 2024) Odhiambo, Charles O.; Ngugi, Charles C.; Sharma, Rekha R.; Oyoo-Okoth, ElijahLand use practices near river ecotones result in numerous inputs of terrestrial materials into the river ecosystem. While macroinvertebrates population metrics is widely used in monitoring water quality changes, including those induced by humans, the use of lipid profiles in these organisms to monitor influence of land use practices is rather ignored. The aim of this study was to determine lipid profile in macroinvertebrates as potential indicator of human influence in Sagana River Basin, a high altitude tropical highland stream in Kenya. Sites were selected based on differences in land use activities delineated: forest with minimal land use activities, while cropland and saw milling areas had varying degrees of land use activities, with urban areas designated as sites with most human impacts. The macroinvertebrate metrics such as occurrence, abundance, diversity, percentage of oligo chaetes and chironomids (%OC), as well as the Ephemeroptera, Plecoptera and Trichoptera (%EPT) index differed relative to land use changes. Variation in the Fatty Acids (FAs), alcohols and sterols in benthic mac roinvertebrates was related to the land use activities along the stream. Evidently, streams traversing the urban areas had higher concentrations of Phospholipid fatty acids (PLFA), while streams traversing croplands had the highest neutral lipid fatty acids (NLFA). The dominance of monounsaturated FAs (MUFAs) in forest, shortchain FAs (SCFAs) and polyunsaturated FAs (PUFAs) in croplands and longchain FAs (LCFAs) near urban areas clear indicate different sources of these materials, mainly from terrestrial sources. Individual fatty acids, alcohols and sterols profiles discerned difference in land use changes. The concentrations of SCFAs, MUFAs, LCFAs, TeoH, 27Δ5.22, 28Δ5,24, 28Δ5,22, 29Δ5,22 and 29Δ5,22 in the benthic macroinvertebrates samples were positively associated with OC%, EPT, total abundance and eH’. Meanwhile the concentration of phytol, AqOH, 27Δ5 and SCOH were associated with Simpson index. The current findings support the combination of macroinvertebrates species composition, abundance, diversity and lipids profiles to detect land use activities at the riverine scale. While implementing catchment-based river management and conservation activities should incorporate lipid analysis as a management tool. There is need for continuous monitoring of long term trends in land use activities on the changes in lipid content of the macroinvertebratesItem Spawning interactions between hatchery-reared and wild naturalized rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in high-altitude tropical streams, Kenya(Wiley, 2022-07) Njue, Justus N.; Ngugi, Charles C.; Mucai, Muchiri; Opiyo, Mary A.Rainbow trout (Oncorhynchus mykiss) is among the most widely translocated fish species in the world. The current study evaluated the spawning interactions between naturalized and wild rainbow trout from two high-altitude second-order streams, in Kenya. Data on total length, weight, condition factor, fecundity, fertilization, egg diameter and fry survival were collected on spawning rainbow trout between March and December 2021. Length–weight relationship showed parabolic equations as W = 0.0144L2.900, W = 0.0069L3.0285 and W = 0.00027L3.175 for wild fish stock, hatcheryreared and wild × hatchery-reared rainbow trout, respectively. Total fecundity differed significantly among the hatchery-reared, wild fish and the cross of the two (p < 0.05). The fertilization rate showed significant differences (p < 0.05), with no discernable difference observed between the hatchery-reared and crossed (wild × hatchery-reared). There was a positive correlation among the total fecundity to female egg weight, female body weight, fertilization rate and eyed egg survival in all the populations. Relative fecundity was significantly different among the three groups of fish (p < 0.05), but the differences between the hatchery and the crossed (wild × hatchery-reared) fish showed no significant differences. We recommend the use of crossed (wild × hatchery-reared) populations for fry production for use in aqua-culture as they presented the highest fecundity and gave the best outcome of fry with high survival.Item Different levels of probiotics affect growth, survival and body composition of Nile tilapia (Oreochromis niloticus) cultured in low input ponds(Elsevier, 2019) Ngugi, Charles C.; Karisa, Harrison Charo; Jumbe, James; Opiyo, Mary A.A 7-month experiment was carried out to determine the effects of different levels of probiotics (baker’s yeast (Saccharomyces cerevisiae) and Bacillus subtilis) on Nile tilapia (Oreochromis niloticus) reared in low input ponds. Monosex male fingerlings (40 g) were randomly distributed into 28, 1.25 m3 net cages at 50 fish m−3 and fed twice daily at 3% body weight on seven isonitrogenous (28% crude protein) diets supplemented with either Saccharomyces cerevisiae (1 × 1010 CFU g−1) or Bacillus subtilis (1 × 109 CFU g−1) at different levels: Diet 0 (control); Diet 1–3 were supplemented with S. cerevisiae at 2 g kg −1 (Diet 1); 4 g kg−1 (Diet 2) and 6 g kg −1 (Diet 3) whereas Diet 4–6 were supplemented with B. subtilis at 5 g kg−1 (Diet 4); 10 g kg−1 (Diet 5) and 15 g kg−1 (Diet 6). Higher final weight (255.31 ± 3.19), Specific Growth rates (SGR) (0.77±0.01) and better Feed Conversion Ratio (FCR) (1.61 ± 0.02) were recorded in fish fed on Diet 2 followed by fish fed on Diet 5. Fish fed on probiotic- supplemented diets had significantly better growth, nutrient utilization and FCR compared to fish fed on the control diet (P < 0.05). Probiotic supplementation significantly affected the body composition of the fish (P < 0.05). S. cerevisiae led to significantly high protein (86.06%) at 4 g kg−1 (Diet 2) (P < 0.05) while B. subtilis led to significantly higher protein (89.40%) at 5 g kg−1 (Diet 4) (P < 0.05). Crude lipid and ash content were significantly lower in the fish fed on probiotic supplemented diets (P < 0.05) compared to the control. This study has demonstrated that the application of probiotics in diets of Nile tilapia in low input ponds promotes growth and enhances body composition. The two probiotics have got different effects depending on the level of application. S. cerevisiae exhibited the best performance at 4 g kg−1 while B. subtilis had the best performance at 10 g kg−1Item Dietary administration of probiotics modulates non-specific immunity and gut microbiota of Nile tilapia (Oreochromis niloticus) cultured in low input ponds(International Journal of Veterinary Science and Medicine, 2019) Ngugi, Charles C.; Jumbe, James; Opiyo, Mary A.; Charo-Karisa, HarrisonItem Assessment of Growth Performance of Monosex Nile Tilapia (Oreochromis Niloticus) in Cages Using Low-Cost, Locally Produced Supplemental Feeds and Training Fish Farmers on Best Management Practices in Kenya(2018) Bundi, James M.; Ngugi, Charles C.; Fitzsimmons, Kevin; Manyala, Julius; Kimotho, Ann N.; Amadiva, Judith M.; Ndogoni, Julius N.; Munguti, JonathanChanging technology in aquaculture has been the major driving force for increasing aquaculture production in the phase of dwindling open water stocks. The choice of technologies and their adoption still remain a focus to increase production, productivity and farm incomes. We assessed the growth of Nile tilapia using locally available materials that included cages and low cost feeds to increased tilapia production in ponds. Various interventions were used among them experimental trials where we formulated low cost diets replacing expensive fish meal. A series of four workshops were also conducted over the course of this project period under this intervention. The first workshop on the development and use of best management practices in aquaculture was held in August 2014. This workshop targeting women in aquaculture had 18 women in attendance. There were two subsequent workshops, held in March and August 2015, and attended by fish farmers from Kirinyaga County. The fourth workshop was held for two days between 2nd and 3rd October 2015. This workshop specifically targeted the youth in aquaculture aimed at training the youth on integrated cage and pond culture focusing on development of cage culture in reservoirs located in the county of Kirinyaga that are presently underutilized by the communities. Graduate support covered three female students who selected because of their previous linkage with AquaFish CRSP and excellent role they continue to play in development of aquaculture in this region. Among them two have submitted their theses for examination. We submitted five peer reviewed publications during this project period with two being specific on low cost feed and fish meal replacement. AquaFish provided funds for HCPIs and graduate students to attend National, Regional and WAS Meetings and Conferences as well. We note that farmers adopted feed technology very well and in their survey feed formulation and fish breeding were their priority. Under lesson learned, we noted that farmers required frequent visits, simple materials for reading and constant communication. They also require strategies on fish marketing such as use of cell phones applications and Aquashops.Item 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.Item 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, AnnA 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