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

Abstract

This study evaluated the effects of soy protein ratio, lipid content and the minimum dietary level of krill meal in plant-based diets over the growth performance and digestibility of Litopenaeus vannamei. Nine plant-based diets varied the soybean meal (SBM) and soy protein concentrate (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 additional diet containing 120 g kg−1 of fish meal (salmon by-product) was used as a control. Krill meal was included at 0, 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 of SBM:SPC ratio and dietary lipid content was detected on shrimp survival. However, dietary lipid levels of 80 and 121 g kg−1 combined with a high SPC to SBM resulted in the lowest final body weight and the poorest apparent crude protein digestibility, respectively. Krill meal increased feed intake at only 10 g kg−1, while at 20 g kg−1, it accelerated shrimp growth, increased yield and reduced food conversion ratio.