Egg- and seashell waste as a calcium source in snail (Cornu aspersum Müller, 1774) feed: I. Growth, mineral distribution in meat, shell and faeces, and environmental effects

Abstract

This study evaluates the effect of diets containing three different sources of calcium (limestone, eggshell, and seashell) on the mineral composition of meat, shell, and faeces and their effect on shell structure and growth of Cornu aspersum. The diets were designated by the calcium source in their diets: chicken eggshell with its membrane (EG), seashell (SS), and limestone (LM). The results showed that the calcium content and mineral concentrations in the diet groups varied significantly depending on the calcium sources. The calcium sources influence the growth and excretion of minerals in the flesh, shell and faeces of the snails. The EG-feed had higher phosphorus (P) and zinc (Zn) levels than SS-feed and LM-feed. At the end of the experiment, the EG-group had grown larger than the other groups. The SS-group showed the lowest growth rate due to the high concentration of non-nutrient elements. Considering environmental implications, the lowest level of phosphorus, potassium and harmful heavy metals was found in the faeces of the EG group and the maximum amount in the SS group. In summary, the study shows that using eggshells offers a dual environmental benefit by recycling waste eggshells and releasing less P and K into the environment.