Potential of Bacterial Strains Isolated from Coastal Water for Wastewater Treatment and as Aqua-Feed Additives

Bacteria have various and sustained effects on humans in various fields: molecular biology, biomedical science, environmental/food industry, etc. This study was conducted to evaluate the wastewater treatment capacity and feed-additive fish-growth effect of four strains of bacteria: Pseudoalteromonas mariniglutinosa, Psychrobacter celer, Bacillus albus, and Bacillus safensis. In a wastewater degradation experiment, (i) nitrate-N and nitrite-N were removed within 1 h in all of the 4 bacterial strains; (ii) the removal rates of TAN and TN were higher in all of the strains relative to the B. subtilis. In a feed-additive experiment (5% Kg−1), (i) the growth of fish was higher in all of the 4 bacterial strains with the B. subtilis relative to the commercial feed; (ii) there was no significant growth difference for B. albus and B. safensis relative to the B. subtilis, but growth was higher in P. mariniglutinosa and P. celer. The results indicated that the 4 bacterial strains can be effectively utilized for biological wastewater treatment processes and as aqua-feed.

Critical Aspects of Aquafeed Value Chain in the Kenyan Aquaculture Sector- A Review

This article reviews critical aspects of the aquafeed value chain in the Kenyan aquaculture sector. Aquaculture production in Kenya has grown steadily in recent years, to more than 18,000 tons in 2019. Due to the growing demand for fish and fish products, there has been a gradual shift from extensive to semi-intensive to moderately intensive aquaculture systems, leading to an increased demand for high quality commercial fish feeds. The current annual demand for fish feed in Kenya is estimated at 34,000 tons. It is the lack of sufficient and high-quality local fish feed production that has created a market for fish feed importers, which is currently estimated at 7,000 tons annually. However, the imported fish feed is expensive for most fish farmers, leading to low production. Local fish feed production through home-based formulation should be driven by fish farmers to contain the rising cost of feeds. Most cottage feed manufacturers produce mash, crumbles or sinking pellets because they lack extruder for making floating pellets, hence the need for quality control in the aqua-feed sector. Fish feed producers are weakly covered by financial services providers, hence the inability to compete effectively with other value chains. The paper outlines five key actors in the aqua-feed value chain from production to marketing. These include; raw material (ingredients) suppliers, feed manufacturers (feed formulators), distributors/wholesalers, retailers, and customers who are fish farmers. We recommend intensification of local aqua-feed production using locally available materials to reduce the importation. This will ensure the long term economic and ecological sustainability of the aquaculture sector. There is a need for favourable policies to lower importation rates for raw materials as a way of boosting the availability of additional feed resources and inputs.

Chemical characterisation and in vitro assessment of two mushroom stalks as prebiotics for Clarias gariepinus (Burchell, 1822)

The potentials of mushroom stalks as supplements in aqua-feeds have been grossly underutilised. Stalk meals of two Pleurotus species were analysed for proximate composition, fibre fractions, mineral and phytochemical constituents. In vitro digestibility and fermentability were assessed using caecal digesta from Clarias gariepinus (n = 108; weight: 138 ± 10.8 g). Stalks of Pleurotus pulmonarius and Pleurotus ostreatus were air-dried at ambient room temperature and milled. Pleurotus ostreatus contained higher (P < 0.05) moisture, crude protein, ether extract and crude fibre than P. pulmonarius stalks which had higher (P < 0.05) nitrogen-free extract. Pleurotus ostreatus had higher (P < 0.05) neutral detergent fibre, acid detergent fibre, acid detergent lignin and cellulose but lower (P > 0.05) hemicellulose than P. pulmonarius. Except in manganese and iron content, P. ostreatus contained higher (P < 0.05) sodium, calcium, magnesium, potassium, phosphorus, copper and zinc than P. pulmonarius. Both stalks contained flavonoids, phlobatannin, terpenoid, cardiac glycosides, steroids and antraquinone. Substrate loss was higher (P < 0.05) in P. pulmonarius (0.20 g) than P. ostreatus (0.15 g). Maximum rate of gas production was more (P < 0.05) for P. pulmonarius (0.16 mL/h) at 4.96 hours compared to 0.04 mL/h at 6.04 hours for P. ostreatus. Both stalk meals were partially resistant to in vitro digestibility and were fermentable. Hence, they possess favourable prebiotics characteristics and can be used as supplement in aqua feed.

Nutraceutical records of aquatic plants (Heinsia bussie and Diplazium sammatii) of lesser known values in Akwa Ibom State, Nigeria

Nutraceutical evaluation was determined for two aquatic plants: Heinsia bussie and Diplazium sammatii. Plant leaves were collected from a stream in Mbak Ikot Abasi in Etoi, Uyo, Akwa Ibom State, Nigeria and analyzed for phytochemicals, nutrients, anti-nutrients, minerals and vitamin constituents using standard analytical methods. Phytochemical screening revealed the presence of bioactive compounds: alkaloids (7.26+0.06), tannin (1.05+0.37), saponin (1.68+0.42), flavonoids (7.83+0.11), cardiac glycosides (6.94+0.48) and terpenes (6.03+0.47) in H. bussie while alkaloids (7.74+0.05), tannin (0.03+0.00), flavonoids (5.37+0.83) cardiac glycosides (4.66+0.38) and terpenes (5.17+0.21) in mg/100g were found in D. sammatii. Results also showed that the leaves contained appreciable amounts of essential nutrients such as crude protein: 11.90±0.62% in H. bussie and 10.80±0.07% in D. sammatii; carbohydrate, 49.70±0.41% in D. sammatii and 39.90±0.02% in H. bussie. Other components like ash and lipid were also present in appreciable amounts. Anti-nutrients such as phytate, saponin and tannins were significantly (p=0.05) low in both vegetables. Minerals analysis showed the highest values for iron (12.05+0.0807mg/kg) and potassium (9.04+0.0307mg/kg) in D. sammatii. Other minerals such as calcium, phosphorus and magnesium were moderate in both vegetables. The vitamins recorded were axephthol, thiamin, riboflavin and ascorbic acid and were significantly (p=0.05) high. The plant leaves could be said to possess vital phytochemical and nutritional properties as well as essential mineral elements and vitamins. Therefore, these vegetables could be utilized as dietary supplement for aqua-feed production. Keywords: H. bussie, D. sammatii, nutraceutical, Athyriaceae, Rubiaceae

Effect of Vitamin D on the Growth, Haematological and Bio-Chemical Profile of Labeo rohita

Background: Fish health and disease management is the key factor in modern aquaculture where intensification manifolds the infestation chances of parasites. Irrespective of antibiotics, the use of dietary additives gaining attention in development of aqua feed. Vitamin D is an important dietary additive for fish in terms it can boost up the immune system of fish and unluckily fish cannot synthesize vitamin D itself. Methods: The present study was planned to determine the effect of vitamin D as feed additive on the immunity, hematology and body composition of Labeo rohita. Four diets (T1, T2, T3, T4) containing different concentration of vitamin. D (250mg, 500mg, 1.0g and 1.5g) in food and a control diet were administrated for 90 days trial. Result: At the termination of experiment there were significant differences in growth and hematological parameters between control and test diets. T3 (1.0g of vitamin D) showed the maximum weight gain with lowest FCR value (1.43±0.33) however, the RBC count of T4 group was highest (1.85±0.07) than the control, T1, T2 and T3 groups. The body composition of Labeo rohita growth factor and survival rate were significantly higher (P is less than 0.05) in fish fed on diets containing vitamin D at 1.00g/Kg concentration.

The Effect of Different Energy Source on the Growth Performance of Clarias gariepinus Fingerlings

This study was aimed to evaluate and compare the effects of different selected energy feed stuff namely; Maize (DT1), Guinea corn (DT2), millet (DT3), and wheat (DT4) on the growth performance and body composition of African sharptooth catfish (Clarias gariepinus Burchell) fingerlings. This energy feedstuff in addition with other feed ingredients was used to formulate four (4) isonitrogenous and isoenergy diets at 40% crude protein. The energy feedstuffs were formulated at 36.31%, 38.26%, 37.09% and 40.05% level of inclusion respectively. The experiment in the ponds used a set of 2 hapas with mesh size 2 mm in each pond measuring 1.62 m2, therefore replicating the experiment 2 times in a completely randomized design The evaluation of the physical parameters revealed that there was no significant difference (p>0.05) in moisture, ash, lipid, fibre, protein and nitrogen free extract among the treatment (diets). The diet with maize (DT1) has the highest growth rate followed by diet containing millet (DT3), guinea corn (DT2) and diet containing wheat (DT4) had the lowest growth rate. This study, revealed that, among the energy feedstuffs evaluated maize (DT1) produced better growth parameters and could be recommended for on-farm aqua-feed.