Lipid nutrition on gonad development of mahseer, Tor tambroides broodstocks

Abstract

The present research was conducted to investigate the effects of fish oil (FO) substitutions with corn oil (CO) and lipid levels on the gonad development of Tor tambroides broodstocks via three feeding trials. The first feeding trial was conducted to examine the effects of diets containing various FO and CO ratios on female T. tambroides broodstocks. Three isonitrogenous (450 g kg-1 crude protein) and isolipidic diets (105 g kg-1 crude lipid) were formulated to contain FO and CO at ratio of 1:0 , 1:1, and 0:1, respectively and was fed to the female broodstocks for five months. Based on the gonadosomatic index (GSI), hepatosomatic index (HSI), histological observations on the gonad cell, muscle fatty acids (FA) composition, and 17β-estradiol (E2) level, fish fed with diet containing FO to CO ratio of 1:1 demonstrated higher GSI and the farthest development of gonad cell stages for female T. tambroides with ratio of n-3 to n-6 of 0.74. To further elucidate the effects of lipid on T.tambroides broodstocks, the second and third feeding trials were conducted with isonitrogenous (450 g kg-1 crude protein) diets containing 60, 82, 105 and 128 g kg-1 of lipid (0, 2.5, 5.0 and 7.5% lipid inclusion respectively) with FO to CO ratio of 1:1 on female and male T. tambroides broodstocks respectively, for five months.