Zinc-threonine enriched yeast improved the growth and mineral composition of marine rotifer, Brachionus plicatilis

Abstract

The survival and larval growth of marine fish in mass production are affected by the nutritional value of live feeds such as rotifers, thus many studies have been conducted to develop effective methods for the enrichment of live feeds with mineral, essential fatty acids and vitamins. In this study, the effect of zinc-threonine enriched yeast on growth factors and mineral composition of rotifer was investigated. For this purpose, rotifers in four groups including: 1) yeast without enrichment (the control), 2) yeast contain 18.22 mg.g-1 of zinc 3) yeast contain 23.76 mg.g-1 of zinc and 4) yeast contain 46.15 mg.g-1 of zinc were cultured for 10 days. Total rotifer and egg number, on a daily basis were assayed. Mean of specific growth rate and egg ratio of the rotifer B. plicatilis were calculated. Changes in the amount of four element (Zn, Cu, Fe and Mn) of rotifer fed with different treatments were also studied. Based on results, zinc-threonine enriched yeast with 46.15 mg.g-1 of zinc-threonine significantly (P<0.05) improved growth and body composition of rotifers. Maximum number of rotifers and eggs were respectively 219.3±2.0 and 30.3±11.0 number.ml-1. The maximum egg ratio and SGR is related to the treatment of 23.76 mg.g-1 and 46.15 mg/g of zinc, respectively. Highest amount of zinc in treatment 4 was 19.54.73±0.99 mg.g-1 (wet weight of rotifer). Also the amount of Cu in treatment 4 was significantly higher than other groups. Conversely, by increasing zinc content, iron and manganese levels were significantly decreased (P<0.05). In conclusion, zinc-threonine enriched yeast could improve the growth, reproduction and body composition of marine rotifers, Brachionus plicatilis.