Effects of seasonal variations, thyroid and steroid hormones, and carp pituitary extract on the artificial production of channel catfish Ictalurus punctatus x blue catfish I-furcatus hybrids

The primary objective was to compare thyroid hormones and levels of carp pi tuitary extract for the artificial production of female Ictalurus punctatus x male l. furcatus hybrid catfish. The effects of different carp pituitary extract dosage rates (5, 6, 9, and 10 mg/kg), carp pituitary extract (6 an d 10 mg/kg) supplemented with the thyroid hormones thyroxine (T-4) and trii odothyronine (T-3), or pregnenolone (DL-IP) were determined for inducing ov ulation of female channel catfish, fertilization of channel catfish eggs wi th male blue catfish sperm, and hatching rate of these embryos. Hormone tre atments thyroxine and triiodothyronine with carp pituitary extract, carp pi tuitary extract alone, and pregnenolone with carp pituitary extract used to artificially produce hybrid catfish were not different in terms of ovulati on rates, eggs/kg, fry/kg body weight of female channel catfish, fertilizat ion rates, or hatching rates (P > 0.05). These findings suggest that lower amounts of carp pituitary extract may be used to induce spawn of female cha nnel catfish for production of channel-blue catfish hybrids and the additio n of thyroid and steroid hormones is ineffective at the rates used in this study.