School of Natural Resources and Environmental Studies
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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 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 CharoThe 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.