Effects of soy protein ratio, lipid content and minimum level of krill meal in plant-based diets in the growth and digestibility of the white shrimp, Litopenaeus vannamei.

Abstract

This study evaluated the effects of soy protein ratio, lipidcontent and the minimum dietary level of krill meal inplant-based diets over the growth performance and digestibility of Litopenaeus vannamei. Nine plant-baseddiets varied the soybean meal (SBM) and soy protein con-centrate (SPC) inclusion ratio at 1 : 2.3, 1 : 1 and 2.5 : 1,and their dietary lipid content at 121.4 9.4, 102.3 1.2,and 79.9 1.2 g kg 1 (in a dry matter basis). An addi-tional diet containing 120 g kg 1 of fish meal (salmon by-product) was used as a control. Krill meal was included at0, 5, 10, 20 and 30 g kg 1 in a new set of plant-based diets.After 10 weeks in clear-water tanks of 0.5 m3 , no effect ofSBM:SPC ratio and dietary lipid content was detected onshrimp survival. However, dietary lipid levels of 80 and121 g kg 1 combined with a high SPC to SBM resulted inthe lowest final body weight and the poorest apparentcrude protein digestibility, respectively. Krill meal increasedfeed intake at only 10 g kg 1 , while at 20 g kg 1 , it accel-erated shrimp growth, increased yield and reduced foodconversion ratio