Abstract: Background and Objective: Mass mortality of earthen-pond reared Clarias gariepinus and hybrid catfish juveniles were reported to the Veterinary Teaching Hospital of the University of Ibadan, Nigeria. The incidence of the disease condition, especially with the presence of aquatic snails in the culture facility that is stream-fed necessitated clinicopathological and epizootiological investigations to determine the causal factor and the course of the disease. Materials and Methods: Five samples of each clariid catfish species were clinically examined, sacrificed and dissected for autopsy. Microscopy of gill tissue, skin, and intestinal scrapings, as well as crush preparations of the liver, the kidney and the eye lens, was conducted. Also, 5 aquatic snail samples were cracked open and snail tissues were subjected to microscopy. Experimental infection was conducted by making 10 healthy catfish juveniles cohabit with 20 infected snails. Results: Numerous cysts were observed in the gills of the fish samples submitted for clinical examination, with severely disrupted structures. Microscopy of the snails revealed the presence of numerous cercaria, and that of the gills revealed the presence of cysts identified to be metacercaria of a digenea trematode. Experimental infection confirmed transmission of the trematode from snail to fish. Mass fish mortality reported was occasioned by decreased respiratory tolerance due to severe gill damage caused by the invasion of the digenea metacercaria. Conclusion: The aquatic snail observed in the affected ponds is the first intermediate host of the worm. Aquatic snails should therefore be eliminated from ponds as part of routine pond preparation to reduce the risk of digenea infection and possible zoonosis. PubDate: 13 January, 2023
Abstract: Background and Objective: In Nigeria, there is a paucity of information on the genetic similarity among wild Oreochromis niloticus species. Though there are assertions based on morphological observation, by fish farmers and some researchers of fisheries that most of these species in the wild are no longer pure and possibly hybridizing. Most molecular assessments are usually among tilapia species with limited sample coverage of O. niloticus species or of a lower marker. This was a preliminary investigation of the genetic similarity of Oreochromis niloticus from selected water bodies along the River Niger, in six states of Nigeria, using SSR markers. Materials and Methods: Similarity levels among Oreochromis niloticus from water bodies in six states in Nigeria were assessed using seven SSR markers with their various primers (UNH 208, 143, 104, 022, 119, 180 and 156), which were selected from the NCBI database. Only UNH 104, UNH143 and UNH 022 produced DNA amplifications. Phylogenetic representation using UPGMA cluster analysis produced a dendrogram with a total of 118 clusters grouped into 7 major clusters with up to 8 subgroups, indicating different degrees of variation and similarities. Results: Genetic similarities were observed at various coefficient levels, possibly due to hybridization. At the coefficient level of 1 or 100%, 39 clusters occurred with different samples on each cluster indicating they are genetically the same. Samples from South Delta (SSD), South West Oyo (SWO) and North West Kebbi (NWK) states were always present in each cluster at this coefficient level. A lot of migration is likely taking place among these fishes. The seven major clusters A, B, C, D, E, F and G at varying degrees of similarity 73, 67, 64, 59, 56, 48 and 44% showed the decreasing order of genetic similarity. Conclusion: These data supported the view that the very high similarity between tilapia from these water bodies stems from its highly prolific nature which may have led to a high probability of hybridization between species and strains. The genetic distance between strains may suggest that there are varying levels of genetic variability among O. niloticus in Nigeria water bodies under study. PubDate: 13 January, 2023
Abstract: Background and Objective: Adaptogens are plant substance that is known to enhance the productivity of animals mainly through their stress mitigating effects and hence the present study was undertaken with the main purpose to evaluate the effect of phytogenic feed additive (PHFA) on growth performance parameters in Litopenaeus vannamei under field conditions. Materials and Methods: The experimental shrimp for this study were post-larvae 10 (PL 10) and 112,000 shrimps were reared in two ponds (9.6×40×1.2 m). One pond served as the control group and was fed with a basal diet, the other pond was considered as a PHFA group fed with a basal diet plus PhytoceeTM (2 kg/ton). The water quality parameters such as dissolved oxygen, temperature, pH, total ammonia nitrogen and nitrites were measured every day. Salinity was measured every 3 days. Litopenaeus vannamei shrimps were fed with respective diets for 104 days. Results: The total body weight (kg), FCR and survival rate (%) exhibited by control and PHFA groups were 1,108 & 1,145, 1.173 & 1.135 and 91.01 & 94.05, respectively. Results revealed that body weight (kg), FCR and survival rate (%) of L. vannamei were improved following the addition of PHFA at 2 kg/ton as compared to the control group. This could be due to the impact of individual ingredients which was already known to have adaptogenic, antioxidant and immunity-booster property. Conclusion: In conclusion, the addition of PHFA at the dose level of 2 kg/ton of feed could be recommended for the augmentation of the growth performance parameters of L. vannamei. PubDate: 01 January, 2023
Open Access journal
[61 journals]
