Effect of simultaneous administration of 17 alfamethyltestosterone and of 3,5,3-triiodo-l-thyronine in starter diets on rearing of whitefish [Coregonus lavaretus L.] larvae

Whitefish (Coregonus /avaretus 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 a-methyltestoste rone (MT) and 3,5,3' -triiodo-L-thyro nine (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 ppm MT + 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, D and E) were more advanced in larval development (LDS)(P<0.05) than the controls. There were no statisti­ cally significant differences in mortality between the feeding groups.

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