Californian red worm biomass increase and its cobalt accumulation under different concentrations of the metal in nutrient medium

Abstract

<p>Californian red worms hybrid biomass is a biologically valuable feed supplement for livestock, poultry and fish. The worm body contains a significant amount of protein, lipids, vitamins and minerals. The chemical composition of worms depends on the nutrient medium in which they were grown. Worms can accumulate minerals from the nutrient medium in the body which called forth conducting research on obtaining worms biomass enriched with Cobalt with the prospect of its further use in fish feeding.<br />It has been found out that the worms quantity and the mass increase depends on the content of Cobalt in the nutrient medium. Adding 20 mg / kg of Cobalt to the nutrient medium contributed to 38.0% and 40.4% increased amount of worms weighing 0.4-0.8 g respectively. The study reveals that the number of immature worms increased by 32.2%. Adding 40 mg / kg of Cobalt to the nutrient medium resulted in worms number and mass increased by 45.9 and 51.1% respectively. Adding 160 mg / kg of Cobalt resulted in 6.5-27.7% smaller amount of worms weighing 0.4-0.8 g as compared with the experimental groups. It has been found out that the number of small worms reduced by 24.0-50.7% compared with the experimental groups under adding 160 mg / kg of Cobalt. The weight reduced by 22.4% and amount of young worms compared with the control has been revealed.<br />We have established the pattern that as Cobalt amount in the nutrient medium increases, its concentration in the worms biomass increases as well. The highest content of Cobalt was found in the biomass dry matter of worms grown in the nutrient medium enriched with the studied metal in the amount of 160 mg / kg.<br />Biomass of worms grown in the nutrient medium with 40 mg / kg of the studied metal added can be used in fish feeding as a protein supplement with a high content of Cobalt.</p>