Effect of oral 17β-estradiol on zootechnical performance, sex ratio and first maturation of mullet Mugil liza Valenciennes, 1836

Abstract

The Mugil liza mullet is a pelagic fish, widely distributed on the Atlantic coast of South America. Its female gonads have high value and market demand, which makes the female monosexual breeding desirable. The objective of this work was to use the hormone 17β-estradiol orally in juveniles to increase the proportion of females, evaluating the zootechnical performance and the first sexual maturation. There were five treatments: 60, 80, 100, 120 and 140 mg of 17β-estradiol per kg of diet and a control without hormone use for 60 days. Each experimental unit was stocked with 150 fish, weighing 0.15 ± 0.7 g and measuring 2.1 ± 0.5 cm. The first sexual maturation was observed at the end of the second year of life. Male (94.64%), female (1.78%) and intersexual or ovotestis (3.57%) gonads were identified. In the majority (96.22%) of the male gonads of the fish that received the hormone, there was a change in morphology, mainly in the treatments that received higher doses. Hormonal treatments affected the gonads, but there was no sexual inversion. As the species presents sexual differentiation several months after fertilization, other tests must be performed, changing the initial size of individuals and the duration of treatment. The higher frequency of males indicates that, in addition to genetic factors, environmental factors may be acting on sex determination mechanisms.