Evaluation of Reproductive Characteristics and Feed Utilization of Two Strains of Heterobranchus bidorsalis (Geoffrey, 1809)

Abstract

Intraspecific hybridization studies were carried out in two strains of Heterobranchus bidorsalis obtained from two ecological zones in Nigeria – Yola (Sudan savannah) and New Bussa (Guinea savanna) with the aim of evaluating the fecundity, percentage fertilization, hatchability, growth rate and survival rate pure breeds and hybrids of both strains. The study was conducted in triplicates for a period of 56 days. Heterobranchus bidorsalis strains obtained from Yola had higher fecundity compared to the New Bussa broodstock. The average number of eggs in one gram obtained from female Yola broodstock (680) was significantly greater than those obtained (per gram) from the female New Bussa broodstock (647). The mean weight of female broodstock obtained from Yola was 7.8 kg while that from New Bussa was 2.5 kg, with a mean total length of 102 cm and 75 cm respectively and a total weight of 400 g and 160 g of stripped eggs. The pure breed (NN♀ x NN♂) and hybrid (NN♀ x YY♂) both had the highest percentage fertilization (30%). The highest percentage hatchability was recorded in the pure breed (YY♀ x YY♂) with 74.43%. In terms of weight (8.80 g) and length (7.22 cm), the pure breed (YY♀ x YY♂) had the best growth performance than the other crosses. YY♀ x NN♂ hybrid had the least growth rate in terms of weight (6.73 g) and length (4.70 cm). There were significant differences (p<0.05) between the specific growth rate (SGR) in the treatments with an average of 5.2%/day. The pure breed (NN♀ x NN♂) had the lowest survival rate (46.7%) and 80% was the highest percentage survival as recorded in the hybrid (NN♀ x YY♂).