Evaluation of nutritional and toxicological effects of Treculia africana (Decne.) seed flour-supplemented diets on Clarias gariepinus (African catfish) fingerlings

A feeding trial was conducted to investigate the nutritional and toxicological effects of full fat Treculia africana seed flour- supplemented diets on growth performance, nutrient utilization, survival, histopathology and blood parameters of Clarias gariepinus juveniles. One hundred and fifty fingerlings of C. gariepinus of average weight of 2.55.96 ± 0.13 g were stocked and fed at 3 % body weight per day for 42 days. Five experimental diets containing 35 % crude protein in which groundnut cake (GNC) meal was replaced by full fat T. africana seed flour meal at 0 % (TAF0), 15 % (TAF15), 30 % (TAF30), 45 % (TAF45) and 60 % (TAF60) were formulated and compounded.   Each treatment had three replicates using 10 catfish per 40-litre capacity plastic bowl. There were no significant differences (P>0.05) in protein efficiency rate and feed intake among the control and experimental fish.  Packed cell volume was highest in fish on TAF45 (45 %) and was higher than fish fed TAF60 (60 %).  Histopathology result showed no visible lesions in some of the tissues of fish fed with the experimental diets.  Full fat T. africana seed flour might not be toxic to catfish; rather it seemed to be a nutritional source. Keywords:  T. africana, C. gariepinus, blood parameters, nutrient utilization, toxicology

Chemical Composition, Microbial Content and Sensory Evaluation of Smoked Farmed Catfish Clarias gariepinus (Burchell, 1822) Raised Under Different Culture Systems in Ibadan, Nigeria

This paper examined chemical composition, microbial content and sensory evaluation of smoked farmed catfish Clarias gariepinus raised in different culture systems with a view to determining its quality and shelf life at ambient temperatures (28 ±2oC) and relative humidity (75% - 85%). Six farms with the two most common fish culture systems (3 concrete tanks (CTs) and 3 earthen pond (EPs) were selected based on frequency of harvest and yield. Fish samples (500±10g) obtained from these farms after 4 months of culture were processed, smoked, packaged and stored for 36 weeks. The values of moisture content, ether extract, crude protein, ash, crude fibre and nitrogen free extract obtained from smoked farmed C. gariepinus during storage ranged from 4.67% – 21.69%; 21.00% - 20.79%; 65.02% - 49.35%; 5.51% - 0.03%; 1.00% - 1.37% and 2.81% - 6.60%, respectively. Highest total viable count (TVC) in processed catfish from both systems (1.27x106±0.01cfu/g) were obtained in the 36th week of storage. Storage time has significant effects (p<0.05) on TVC. Smoked fish from local fish processor (LFP) had highest TVC >107cfu/g. Best sensory scores in processed catfish were 7.0±0.01; 6.5±0.01 and 5.0±0.03 at 24 week of storage for fish from EP, CT and LFP, respectively. All quality and safety indices were within International Commission of Microbiological Specification for Foods acceptable limits. Keywords: Total viable count, smoked fish, quality changes, protein content, textur

Effect of Tamarindus indica (Linn, 1753) pulp and leaf-fortified diets on experimental Aeromonas hydrophila infection in Clarias gariepinus (Burchell, 1822)

Intensification of aquaculture is associated with infectious diseases with consequent increase in the use of synthetic antibiotics. The rise in antibiotic-resistant bacteria is of global criticism. The role of Tamarindus indica as antimicrobial agents has been reported. This study evaluated the utilization of tamarind pulp and Leaves in the diets of Clarias gariepinus as antimicrobial agent against Aeromonas hydrophila infection. Ten experimental diets consisting of 0.5, 1.0, 1.5, 2.0% of basal diets each of tamarind pulp or leaf meal and 0.0% (untreated control) and 0.2% oxytetracycline (treated control) were fed to C. gariepinus for 12 weeks. After the feeding trial, fish were subjected to bath challenge with Aeromonas hydrophila and observed for 28 days to determine mortality and relative percentage survival. The surviving fish after 28 days post-challenge were sampled for haematological studies. Data were analyzed using oneway analysis of variance at P = 0.05. All experimental groups of the fish on tamarind-treated diets exhibited significantly lower (P ˂ 0.05) mortality compared to the groups fed with the control diets. 100% relative percentage survival was exhibited by the groups of fish on 1.5-2.0% pulp and 2.0% leaf diets. Higher white blood cell counts were obtained from tamarind-treated groups compared to the untreated control diets. The heterophil of the challenged fish fed diet with oxytetracycline was significantly lower (P ˂ 0.05) than fish fed 2.0% tamarind leaf diet. Inclusion of tamarind in the diets of the challenged C. gariepinus did not alter the monocytes, eosinophil and basophil significantly (P > 0.05) compared to those on the control diets. Fortifying the diets of Clarias gariepinus with 2.0% tamarind pulp and leaf meal significantly enhanced protection against Aeromonas hydrophila infection, hence these inclusion levels are recommended as alternatives to oxytetracycline in the control of motile aeromonas septicaemia.Keywords:  Clarias gariepinus, tamarind, synthetic antibiotics, Aeromonas hydrophila infection, relative percentage surviva