Faculty of Agriculture, Animal Production and Fish Resources

The use of exogenous hormones to induce final oocyte maturation, ovulation, and spawning has become commonplace in the reproductive protocols for many species. In the present study, African catfish (Clarias gariepinus) were monthly collected from January to December 2011 for studying their monthly reproductive biology. Also, hormonal stimulation was done using ovaprim, human chorionic gonadotropin (hCG), and salmon gonadotropin releasing hormone analog (GnRHa). However, fish (337.2-718.0 g) were divided into seven groups (each group contained four females and four males) and injected into the dorsal musculature by 0.4, 0.5 ml kg-1 Ovaprim, 1000, 3000 IU kg-1 hCG, and 0.75, 1 ml kg-1 GnRHa. The control group was injected by 0.9% saline. At the dosage tested, gonado-somatic index (GSI), absolute fecundity, ovulation index, egg diameter, fertilization rate were significantly affected in all stimulated groups. It was found that the hormonal treatments are a useful method for commercial African catfish breeders to ensure the continuity of access larvae. However, the best reproductive performance was obtained at 0.5 ml kg-1 ovaprim, 3000 IU kg-1 hCG, and 0.75 ml kg-1 GnRHa.

This study  performed to examine the  ability of pawpaw (Carica papaya)  seeds to induce sterility in male  and female of Nile tilapia (Oreochromis niloticus). Five groups were prepared; negative control group with mixed sex fish (G1) and positive control  with monosex fish (G2) fed  on basal diet,  while G3, G4 and G5 were  mixed sex fish fed on basal diet  with addition of 60, 90, 120g  of C. papaya  seeds/kg diet,  respectively. Ten fish with average weight of 30±1g were  stocked at each  of fifteen tanks  (triplicates/treatment) with dimensions 135×50×60cm. Gonado-somatic index  (GSI), egg diameter, fecundity and plasma  sexual hormones level were determined and histological examination of gonads were performed. GSI, egg diameter and fecundity of treated females decreased significantly  (P≤0.05) after treated and recovery months, while GSI of males  was not  significantly  different (P≥0.05) among treatments. The  levels  of testosterone (T) and estradiol  (E2) significantly  (P≤0.05) decreased after treated and  recovery months. All values  decreased gradually  with in- creasing  the  dose of C. papaya  seeds. Histological  sections showed several structural changes in testes and ovaries of the treated groups with different degree according to C. papaya  seeds dose. Sections after recovery month showed that  C. papaya  seeds induced permanent sterility in the high dose while the low and medium doses may have reversible effect. The study  concluded that, the seeds of C. papaya  can be used with adjusted amount as a feed additive to control the problem of precocious maturity  and breeding of O. niloticus in growing ponds instead of unfavorable and expensive hormone.

The use of exogenous hormones to induce final oocyte maturation, ovulation, and spawning has become commonplace in the reproductive protocols for many species. In the present study, African catfish (Clarias gariepinus) were monthly collected from January to December 2011 for studying their monthly reproductive biology. Also, hormonal stimulation was done using ovaprim, human chorionic gonadotropin (hCG), and salmon gonadotropin releasing hormone analog (GnRHa). However, fish (337.2-718.0 g) were divided into seven groups (each group contained four females and four males) and injected into the dorsal musculature by 0.4, 0.5 ml kg-1 Ovaprim, 1000, 3000 IU kg-1 hCG, and 0.75, 1 ml kg-1 GnRHa. The control group was injected by 0.9% saline. At the dosage tested, gonado-somatic index (GSI), absolute fecundity, ovulation index, egg diameter, fertilization rate were significantly affected in all stimulated groups. It was found that the hormonal treatments are a useful method for commercial African catfish breeders to ensure the continuity of access larvae. However, the best reproductive performance was obtained at 0.5 ml kg-1 ovaprim, 3000 IU kg-1 hCG, and 0.75 ml kg-1 GnRHa.