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Optimization of Hormonal Dose During Masculinization of Tilapia (oreochromis Niloticus) Fry

Z. Ferdous
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

M. M. Ali
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Abstract/ Executive Summary:

The experiment was conducted to optimize the dose of 17α-methyl testosterone (MT) during masculinization of tilapia (Oreochromis niloticus) fry. Five treatments were designed with various doses of hormone to find out the most effective one. The treatments were designated as T₁ (0 mg MT/kg), T₂ (40 mg MT/kg), T₃ (50 mg MT/kg), T₄ (60 mg MT/kg) and T₅ (70 mg MT/kg). MT was administered orally by using nursery feed and Ethanol (as hormone carrier solvents) diet to tilapia fry for 28 days in hapa. After completion of the trial period of 28 days nursing of the experimental fry was continued for further 2 months with commercial feed. At the end of experiment the sex ratio was determined by examining gonad after dissecting the fish. Growth performance was monitored by recording the morphometric characteristics i.e. weight gain (g), average daily weight gain (g). The analysis of growth data showed significant variation in weight, % weight gain, SGR (% /day) of fish among the different treatments. SGR increases with the increase of hormone dose. The present study demonstrated that all MT receiving treatments showed a significantly (p<0.01) higher male proportion (94.28%) than control (48.57%). The dose of 60 mg MT/kg of feed resulted in maximum male population (94.28%). The result indicated that the optimum dose of MT hormone was 60 mg /kg with a feeding period of 28 days after hatching.

Keywords: 17?-methyl testosterone (MT), Masculinization, Growth

Location: Bangladesh Agricultural University

Start Date:

End Date:

Program Area: Variety and Species

Commodity: Tilapia

Objectives:

1. To find out optimum dose rate of MT treatment for sex reversal along with its effect on growth performance of Nile tilapia (Oreochromis niloticus).

Methodology:

Sources of fry and experimental design: Nile tilapia (O. niloticus) fry used in the present experiment were collected from “Reliance Aqua Farm”, ?Boilor, Trishal, Mymensingh. Three days old spawns (first feeding stage) of tilapia (O. niloticus) were stocked in 10 (Ten) hapa (Size 6ft×6ft). The experiment was conducted in duplicate with 5 treatments designated as T₁ (0 mg MT/kg), T₂ (40 mg MT/kg), T₃ (50 mg MT/kg), T₄ (60 mg MT/kg) and T₅ (70 mg MT/kg). The fry were reared for 28 days with hormone containing feed. Hormone-feed preparation and feeding trial: Four diets with different doses of MT hormone i.e. 40, 50, 60 and 70 mg/kg were prepared through ethanol evaporation method. To prepare 5 kg feed for each treatment required amount of MT hormone (i.e. 200, 250, 300, 350 mg MT hormone for T₂, T₃, T₄ and T₅ respectively) was diluted with 750 ml ethanol carrier for homogenous mixing with the nursery feed. In case of control, only nursery feed was used without hormone treatment. The fry were fed with hormone mixed feed 5 times (started at 8.00 am and continued up to 6.00 pm with two hour interval) a day up to satiation. The hormone feeding phase was continued for a period of 28 days. The fish were then fed with hormone free commercially available diet for further two months. Growth performance was also calculated. Collection and analysis of data: Ten fry from each of the hapa were randomly selected for measuring weight (g) at an interval of 7 days. At the end of the rearing period, the male and female fish were sexed by gonad squashing and acetocarmine staining method. The weight gain (g), average daily weight gain (g) and specific growth rate (%/day) of fish during experiment with different hormone feeds were tested using one way analysis of variance (ANOVA). The statistical analysis was performed with the aid of the computer software SPSS programme and MS Excel Programme.

Source of Information: J. Bangladesh Agril. Univ. 9(2): 359–364, 2011

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The present study indicates that there is a positive relationship between doses of androgen and the percentage of male fish, but higher dose (70 mg/kg) of hormone resulted in no increase of male fish. The result of the present research revealed that the optimum dose of MT hormone was 60 mg/kg with a feeding period of 28 days. The dose of 60 mg 17α- methyl testosterone per kg of feed was found to be best for inducing sex reversal in O. niloticus resulting 94.28% (higher) male in the population.

Knowledge Management: Journal