EFFECT OF SIMULTANEOUS ADMINISTRATION OF 17 ALPHA-METHYLTESTOSTERONE AND OF 3,5,3’-TRIIODO-L-THYRONINE IN STARTER DIETS ON REARING OF WHITEFISH (Coregonus lavaretus L.) LARVAE

Abstract

Whitefish (Coregonus lavaretus L.) larvae were rearing exclusively on dry diets in water temperature 14±0.5°C for 20 days. Experimental groups received diets containing different levels of 17 α-methyltestosterone (MT) and 3,5,3’-triiodo-L-thyronine (T3). Group B was fed diet with addition of 5 ppm MT, group C 4 ppm MT+ 0.5 ppm T3, groups D 5 ppm MT + 1.5 ppm T3 and E - 6 ppm MT + 3 ppm T3, respectively. Control group (A) was fed on diet without hormones.

At the end of rearing, larvae receiving a diet 5 ppmMT+ 1.5 ppm T3 (group D) were heavier and longer (P<0.05) than all the remaining ones. All larvae receiving the two hormones in diets (groups C,Dand E) were more advanced in larval development (LDS)(P<0.05) than the controls. There were no statistically significant differences in mortality between the feeding groups.