Abstract:

A study was conducted to determine the optimum dosage of Chorulon®, a commercial preparation of human chlorionic gonadotrophin (hGC), for increasing spawning rates in the Nile tilapia, Oreochromis niloticus, under laboratory conditions. Dosages of 500-3,500 IU•kg-^₁ body weight hGC were injected intramuscularly into sexually-mature females reared in fiberglass aquaria. Spermiating males were provided at 1:1 sex ratio. The number of ovulated and mouthbrooding females were determined 24 h after injection. The eggs from ovulated females were stripped and fertilized artificially while those from mouthbrooding females were removed from the oral cavity of the fish. All eggs were transferred to individual zuger jars for determination of pigmentation rates as an indicator of fertilization rates. Results showed that dosages of 2,000-3,500 IU•kg-^₁ hCG were effective in significantly increasing the percentage of females either ovulating or mouthbrooding 24 h after injection (25-75%), with pigmentation rates ranging from 36 to 83%. The optimum dosage of the hormone was 3,500 IU•kg-^₁.

Full text PDF

Date 1994/12/01

Abstract Hits 2832

Downloads 1975