Growth responses and yield of heterotis (Heterotis niloticus) on artificial diet

The growth responses and yield of Heterotis niloticus on artificial diets of varying protein levels were studied in a bid to assess the implication of feeding Heterotis in intensive fish production venture for a rearing period of 84 days. One hundred and twenty juvenile H.niloticus were fed for 12 weeks on 28%, 31%, 34% and 37% dietary crude protein levels. The fish were reared in 4 concrete tanks stocked at the rate of 10 fish per M super(2) 100,00/hectare). Consequently, the weight gain, food conversion ratio, serum protein and albumin-globulin ratio were determined to assess the growth and state of health of the fish. The yield was appraised through economic considerations of cost of production of fish and diets (feed). The varying crude protein levels significantly influenced mean weight gain, percentage weight gain and food conversion ratio however, the 37% crude protein in diet produced the best growth. The serum protein was highest in fish raised on 31% crude protein diet while the highest value was recorded for albumin-globulin ratio on diet containing 34% crude protein. The yield from treatments 1, 2, 3, and 4 were 114.38 of/84 days 571.9kg/g hect);146.79g/84 days 733.95kg/hect), respectively. However, treatment 3 recorded the highest value for profit inde

Nutritional value of mango (Mangifera indica) seeds and peels

The nutritional value of peels and' ~eds' 9f Mango, Mangifera indica was studied by analyzing collected samples of these non conventional feedstuffs for their proximate composition. The result of the analysis shows that moisture ranged from 9.70 to 10.48% (peels) and 9.50 to 10.48% (seeds). Protein ranged from 4.08 to 4.49% (peels) and 5.38 to 8.10% (seeds). Carbohydrate was 49.35 to 62.45% (peels) and 53.64 to 70.58%' (seeds). Fat ranged from 3.98 to 6.30% (peels) and 8.30 to 12.80% (seeds. Ash content ranged from 2.20 to 4.98% (peels) and 2.00 to 3.70% (seeds). The values for the proximate parameters of the peels and seeds were comparable to values reported for other non convectional feedstuffs. The seeds of ti1'ango had higher values than peels

Aflatoxin levels in fish feeds in Abeokuta, Ogun State

Post harvest contamination can occur if drying of feed is delayed and when water is allowed to exceed critical values for mould to grow during storage. This study examined the aflatoxin levels in fish feeds surveyed in Abeokuta, Ogun State, Nigeria. Fifteen (15) fish farms were randomly selected for assessment of the aflatoxin levels in fish feeds in Abeokuta. After the estimation of the aflatoxin levels using Veratox quantitative aflatoxin test, the Aflatoxin concentrations in the samples ranged between 0-49 ppb with a mean value of 6.89 ppb. Results obtained from this study showed that aflatoxins were found to be associated with fish feeds in different fish farms in Abeokuta, but, a very high proportion of the feed samples were below the regulatory levels (maximum of 20 ppb) that may not be toxic to the health of the fish according to the regulatory levels for aflatoxins issued by the Food and Administration of the United States. Thus, feeds fed to the cultured fish species in farms in Abeokuta were fit for consumption, with very little or no threat of aflatoxicosis (a disease that can affect many species of fish, when feed contaminated with aflatoxin is consumed)

Effects of length of delay after slaughter (Lodas) on raw catfish Clarias gariepinus (Burchell, 1822)

The effect of delay after slaughter on microbial quality, proximate composition and sensory scores of raw catfish, Clarias gariepinus was evaluated. A total of 52 live catfish (average weight 700.0~c7.0g) were used for the experiment. Ten freshly slaughtered fish samples each were selected for organoleptic assessment at 0, 4, 8 and 12 hours post-slaughter, while three fish samples each were selected for chemical and microbial analyses. Microbial load on fish samples increased significantly (P< 0.05) with increase in length of delay after slaughter, LODAS. Bacteria isolated included Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus spp and Staphylococcus aureus. Percent protein and ash contents of fish samples increased with increasing LODAS, while moisture content decreased and lipid was not affected. It was observed that raw C. gariepinus retained most of its physical attributes up to 4 hours post-slaughter. These quality attributes except colour and odour of gills, deteriorated significantly (P < 0.05) at every successive four-hour post-slaughter interval. Significant negative correlation existed between LODAS and sensory quality of raw fish (eyes, r = -0.966, P < 0.05; gills, r = -0.980, P < 0.05; skin, r = -0.998, P < 0.01; and odour, r = -0.994, P < 0.01). This study established that quality of raw C. gariepinus deteriorated with increasing LODAS and that raw C. gariepinus was not totally unacceptable when delayed for 12 hours after slaughter at ambient temperatures

Effect of feeding Colocasia (Colocasia esculenta (L) Schottl corn flour as a part of energy supplement on growth and nutrient utilization in Clarias gariepinus (Burchell, 1822) fingerlings

The objective of this study was to compare the nutritive value of boiled Colocasia esculenta flour (CECF) with that of yellow maize in practical rations of fingerlings. Boiling resulted in a slight increase in crude protein content and significant (84.5%) decrease in oxalate content. Five is oproteic (30% crude protein) and isocaloric (15.46 Kjg-1) diets were formulated. The control diet contained maize as the principal dietary energy source, while flour produced from boiled Colocasia corn progressively replaced maize at 5 inclusion levels (0%, 20%, 40% 60% and 80%). The experimental diets were fed to triplicate group of Clarias gariepinus fingerlings (mean weight 2.05~c0.5g) at 3% body weight day-1. Growth performance expressed as weight gain, specific grown rate (SGR) and nutrient utilization expressed as feed conversation ration (FCR), protein efficiency ration (PER) were assessed. There was a trend of decrease in weight gain with increase in inclusion level of CECF. Weight gains of groups of C. gariepinus fed up to 60% inclusion level of CECF were nog significantly (p>0.05) different from the group fed the control diet, the same trend was observed for SGR. FCR and other parameters were poorer (p<0.05) in digestibility coefficients among the different groups, also that carcass composition did not vary significantly (p<0.5) among treatments. Results also indicate that CECF is an acceptable ingredient that can replace maize up to 20% inclusion in C. gariepinus rations

Effects of some plant extracts on some biological parameters of catfish Clarias gariepinus (Burchell 1822)

Preliminary studies on the antimicrobial properties of various methods of extraction of Carica papaya (Pawpaw) seeds, Citrus paradisa (Grapefruit peel) and Piper guineese (Black pepper) seeds against eleven bacteria ( Proteus mirabilis, Escherichia coli, Staphylococcus aureus, Acinetobacter sp, Klebsiella pneumoniae, K. oxytoca, Pseudomonas lundensis, Bacillus subtilis, B. megaterium, Citrobacter freundii and Enterobacter cloacae) associated with fresh catfish spoilage were investigated using the cup-plate diffusion method. Cold water, hot water and ethanol were the different extraction solvents used while the concentrations were 0.1g/ml, 0.2g/ml, 0.3g/ml, 0.4g/ml and 0.5g/ml. Generally, hot water extraction of the plant materials was most effective (p < 0.01) with the highest mean zone of inhibition of 4.42 ~c 0.38mm followed by ethanol extraction (3.55 ~c 0.47mm). The most susceptible bacteria was Enterobacter cloacae with the highest mean zone of inhibition of 22.6 ~c 3.50mm. This investigation indicates that the antimicrobial compounds in grape peel and black pepper are best liberated when extracted with ethanol while that of pawpaw is best extracted with hot water

Bacterial load, composition and succession in the African catfish, Clarias gariepinus (Burchell, 1822) held at ambient temperatures.

Microorganisms, especially bacteria are the major causes of spoilage in fresh fish. In the coastal areas of developing tropical countries where ambient temperatures are usually high and access to modern preservation and processing technologies is low, fish is often left under ambient conditions for long periods after capture, resulting in quality deterioration and spoilage with attendant increases in post harvest losses. This study was carried out to identify, characterize and estimate the number of colony forming units (CFU) of microorganisms associated with freshly slaughtered African catfish, Clarias gariepinus held at ambient temperatures. Microorganisms were isolated from the flesh, gills, guts, mouth and skin of fish samples at successive 6-hour intervals post-slaughter for 42 hours when the fish were adjudged spoilt by a 5-member trained assessment panel. Determination of viable bacterial count was carried out by introducing aliquots of three dilutions of samples into nutrient agar plates, incubating at 37oC for 24hrs and counting the number of CFU. Microorganisms were thereafter identified using colonial and morphological characteristics and biochemical tests. Organoleptic assessment of fish samples were carried out by a 5-man trained panel. Results showed that a total of eleven microorganisms of pathogenic and/or spoilage importance were isolated at various intervals from fish samples, including Acinetobacter spp, Bacillus subtilis, B. megaterium, Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, K. pneumoniae, Proteus mirabilis, Pseudomonas lundensis and Staphylococcus aureus. Generally the number of CFU from various parts of fish increased significantly (P < 0.05) as time interval increased

Role of feed handling in fish farms in Abeokuta, Ogun State, Nigeria

This study examined fish health status in relation to fish feed handling. Twelve (12) fish farms were randomly selected for assessment of types of fish farms, sources, disease problems associated with fish feeds as well as mode of operation and age of farms in Abeokuta, Ogun State Nigeria. Structured questionnaires were administered for data collection. The fish farms surveyed were categorized into three (3) main groups: farms with less than five (5) fish rearing tanks as small scale production (16. 7%), farms with more than five but less than 10 fish rearing tanks as medium scale production (75%) and farms with above ten (10) fish rearing tanks as large scale production (8.3%). The operational methods were fingerlings production (25%), grow-out (table-size) production (25%) and those involved in the production of both fingerlings and table-size fish (50%). All the farms surveyed utilized compounded rations with only one farm combining compounded rations with natural food (artemia). All the farms experienced different levels of limitations in sourcing for feeds. The types of diseases identified on the farms were bacterial disease, parasitic disease as well as water pollution problem. As regards the duration of feed storage, feeds stored for three months and above suffered more disease problems with increase in water pollution level and presence of parasitic disease, while feeds stored for less than two (2) months experienced only bacterial disease. In controlling the highlighted diseases, farms with brood stock fish adopted only the effort of elimination of water (l00%), those involved in fingerlings used antibiotics and malachite green (50% and 100% respectively), those involved in the production of table-size fish used antibiotics (50%), while those involved in production of both fingerlings and table-size employed 100% water elimination

Dietary supplementation of autolysed yeast enhances growth, liver functionality and intestinal morphology in African catfish

A feeding trial was conducted to evaluate the potential of dietary supplementation of autolysed brewer's yeast (AY) on African catfish. The catfish (22.5 ± 1.15 g/fish, 20 fish 33 L/tank) were fed with either of diets (390 g/kg crude protein, 140 g/kg lipid) supplemented with 0, 3, 6 or 10 g/kg AY (n = 3). After 49 days of feeding, the final body weight and metabolic growth rate of the catfish fed 3 g/kg AY (3‐AY) diet were higher than those fed the control diet (p .05) in intestinal perimeter ratio. However, an elevated (p < .05) abundance of goblet cells and intraepithelial leucocytes were found in the intestine of catfish fed 3, 6 and 10 g/kg AY diets, with the highest level of abundance recorded in the mid‐intestine of the catfish fed 3‐AY diet. The results suggest that dietary 3 g/kg autolysed brewer's yeast supplementation improves growth performance of African catfish without deleterious effect on liver functionality and gut morphology

Growth Performance and Nutrient Utilization of African Mud Catfish (Clarias gariepinus) Fingerlings fed Different Levels of Fermented Pigeon Pea (Cajanus cajan) meal

The suitability of fermented pigeon pea meal as a protein ingredient in diets for Clarias gariepinus fingerlings was evaluated. A strain of Rhizopus oligoporus was used to ferment the meal for six days at 37°C. Five isonitrogenous (30% crude protein) and isoenergetic (16.45 MJ/kg) diets were formulated in which fermented meal was used to replace soybean meal at five inclusion levels (0%, 25%, 50%, 75%, 100%). Diets were fed to triplicate groups of C. gariepinus fingerlings for 70 days. Crude protein content (22.6%-27.0%), total sugar, calcium, and phosphorus increased while lipids, carbohydrate, crude fiber, and antinutritional factors decreased in catfish fed increasing levels of pigeon pea meal. The group fed the 100% diet had significantly (p<0.05) better growth, which declined as the inclusion level declined. The apparent digestibility coefficients protein and dry increased with the inclusion level. No histopathological changes were observed in the liver. The highest crude protein content in catfish tissues was obtained in the group that received the highest inclusion level. The study shows that fermented pigeon pea meal can replace soybean meal in practical feeds for C. gariepinus without compromising growth performance or nutrient utilization