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Use of 17α‐methyltestosterone to sex inverse gynogenic female rainbow trout
Author(s) -
Schmelzing Th. O.,
Gall G. A. E.
Publication year - 1991
Publication title -
journal of applied ichthyology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.392
H-Index - 62
eISSN - 1439-0426
pISSN - 0175-8659
DOI - 10.1111/j.1439-0426.1991.tb00518.x
Subject(s) - dose , gonad , methyltestosterone , biology , zoology , body weight , rainbow trout , medicine , testicle , endocrinology , fish <actinopterygii> , fishery , pharmacology
Summary Oral administration of 17α‐methyltestosterone (MT) was used in two experiments to sex inverse gynogenic rainbow trout. In both experiments MT was mixed into the feed in dosages of .5 mg, 1 mg, and 3 mg/kg. In Experiment 1 the treatment lasted for 300° days, 450° days, and 700° days, and in Experiment 2 for 600° days, 750° days and 938° days. Significant Chi‐Square tests (P < 0.01, P < 0.001) regarding the number of phenotypic males in both experiments showed that MT dosage and treatment duration did not act independently. At about 1 year of age the highest numbers of phenotypic males were achieved when a lower dosage (.5 mg or 1 mg) was fed for a longer duration (750° days, 938° days); 100% males were found in the 1 mg‐750° d and the .5 mg‐938° d treatments. In the 1‐year‐old phenotypic males in Experiment 2, body weight and gonad weight were correlated with r = 0.60 (P < 0.001). The analyses of variance showed that body weight was affected by gonad weight group and MT dosage, while gonad weight was not affected by MT dosage or treatment duration. Data on sex distribution at maturity are available for Experiment 1. Here, too, the lower dosages of .5 mg and 1 mg/kg applied for the longer 700° day duration, as well as the 1 mg‐450° day treatment, and achieved the best results of 60% phenotypic males.