EFFECTS OF DIETARY SUPPLEMENTATION OF SOME ETHNOBOTANICALS ON THE REPRODUCTIVE PERFORMANCE OF CLARIAS GARIEPINUS BROODSTOCK

Abstract

The demand for the seed of African catfish Clarias gariepinus is on the increase. This therefore calls for the supply of high quality broodstook that would give yield to high fertilization, hatching and survival of hatchlings. In this study, the effects of dietary supplementation of three ethnobotanicals (Piper guineense, Ocimum gratissimum and Rauvolfia vomitoria) on the reproductive performance of male and female C. gariepinus broodstoock were determined. Three sets of experiment were conducted to determine the effects of the plants on; milt and egg quality, on their gonads and on their sex hormones (testosterone and estrogen level). In the first experiment, 90 broodstocks (45 male an 45 female) with an average weight of 411g and 398.20g (male and female respectively) were distributed into 5 treatments (in triplicate) of eighteen fish per treatment. The fish in the treatments were fed with isonitrogenous (40 % crude protein) diets formulated with the aqueous extract of P. guineense dry fruit at the inclusion levels of 0, 0.06, 0.12, 0.18, and 0.24 g/kg of feed for diets D1, D2, D3, D4 and D5 respectively. Fish were fed at 3% body weight for 70 days at the end of which reproductive indices (egg size, fecundity, percentage fertilization, hatchability and survival), estrogen level, sperm parameters (milt volume, counts, motility duration and percentage motility), and testosterone level in blood were determined. In the second experiment; ethanol extract of O. gratissimum was used to formulate five diets at the inclusion levels of 0, 0.125. 0.25, 0.375 and 0.5 g/kg of feed to form D1, D2, D3, D4 and D5 respectively, and this was used to feed the fish. In the third experiment, aqueous extract of R. vomitoria was included in the diets formulated for the fish at an inclusion levels of 0. 0.05, 0.10, 0.15 and 0.2 g/kg of feed. At the end of the feeding trial, reproductive performance was evaluated for each of the fish in each of the experiments. The result in experiment 1, showed the fish fed D4 had the highest fecundity (57523.67±5770.35), Percentage hatchability (75.73 ± 2.70), survival (67.54 ± 0.76) and highest level of estrogen (3144.20±13.67), while GSI, percentage fertilization and egg size were highest in fish fed D5 (13.34%, 92.54% and 1.57mm) respectively. GSI, milt volume and percentage motility were highest in fish fed D5 while milt count, motility duration and testosterone were highest in fish fed D4, and their differences were significant when compared to fish fed D1. In experiment 2, the result showed that there was significant difference (p<0.05) in the weight of testis, GSI, milt volume, motility duration, percentage motility and testosterone level of fish fed D3, D4 and D5 when compared to fish fed control diets. GSI (20.25%) and fecundity (57235) were highest in fish fed D3, percentage fertilization (89.46%), hatchability (79.39%), survival (60.08%) and estrogen level (3377.60pg/ml) were highest in fish fed D5. In experiment 3, there was no significant difference (p>0.05) in weight of testes, GSI and milt volume in all the diets, while there was significant difference (p<0.05) in milt count, motility duration and percentage motility of fish fed D4 and D5 when compared to fish fed D1. There was no significant difference (p>0.05) in the values obtained in weight of eggs, GSI, fecundity and percentage fertilization, but the highest value of weight of eggs (106.16g), GSI (11.77%), fecundity (54227.33), percentage hatchability (65.89%), survival (61.97%) and estrogen level (28155.39 pg/ml) were obtained in the group of fish fed D4, while percentage fertilization (71.28 %) was highest in fish fed D5. The result got from the three experiments revealed that dietary supplementation of extracts of P. guineense, O. gratissimum and R. vomitoria extracts increased the reproductive performance of C. gariepinus broodstocks and possesses pro-fertility agents which can be exploited in fish seed production.