Effects of Dietary 17α-Methyltestosterone and Bovine Growth Hormone on Growth and Food Conversion of Slow- and Normally-Growing American Elvers (Anguilla rostrata)

Abstract

Dietary addition of 17α-methyltestosterone (MT) and bovine growth hormone (bGH) had a significant effect on growth and food conversion in American elvers (Anguilla rostrata). Both MT (1 μg/g) and bGH (2 and 10 μg/g) significantly increased the mean weight of elvers compared with controls. Higher concentrations of MT (10 μg/g) increased mean body weight, but not significantly. The effects of MT were more pronounced in normally-growing elvers compared with slow-growing elvers. Reduction of water temperature had a much stronger influence on weight gain in slow-growing elvers receiving MT than with normally-growing eels receiving MT. Food conversion was improved by feeding either MT or bGH. Food conversion was generally lower in slow-growing than in normally-growing elvers. Total body protein was related to body weight and was significantly lower in elvers fed MT than in control elvers. However, there was no significant difference in total body protein elvers fed bGH compared with the control group.