Partial or total replacement of fish meal by plant protein affects gonadaldevelopment and plasma 17 beta-estradiol levels in female Nile tilapia

摘要

This study was conducted to evaluate the effect of plant protein-based diets on gonadal development and plasma 17 beta -estradiol (E2) level in female Nile tilapia Oreochromis niloticus. Fish with a mean body weight of 6.7 (0.1) g were fed four different diets with the same digestible protein (DP) and digestible energy (DE) containing graded levels of a mixture of plant ingredients as partial or total replacement of fish meal protein for 20 weeks. The control diet (D0) was based on fish meal, two diets containing 33% (D33) and 66% (D66) of plant protein, and one diet containing only plant protein (D100). Fish were sampled at 12 and 20 weeks. No significant differences were found in different stages of oocyte development and plasma E2 levels between tilapia fed diets D0 and D100 at 12 weeks. Eight weeks later tilapia fed diet D0 showed a higher (P < 0.05) level of E2 than the D100 group. This difference and the reduced proportion of vitellogenic and mature oocytes demonstrated that diets containing only plant protein are less efficient in terms of tilapia growth and consequently ovarian development.