The utility of eggshell for productivity improvement of soft-shell rice-field crab (Sayamia bangkokensis)

Abstract

The purpose of this research was to determine the optimal level of ground eggshell supplementation in the diet for production of soft-shell rice field crab. A completely randomized design was used, consisting of 2 experimental sets: 1 used unheated ground eggshell mixed into the feed, and set 2 used heated ground eggshell mixed into the feed. Both sets included the same concentrations of 0 (control), 10, 15, 20, 25, and 30 percent per kilogram of feed, with three replicates per treatment over a period of five months. The results showed that both experiments exhibited superior growth performance compared to the control group. In set 1, the 15 percent concentration yielded the highest performance, showing a statistically significant improvement (P<0.05), with a weight gain of 9.54 ± 0.90 g. In set 2, the 30 percent concentration produced the best growth performance with highly significant differences (P<0.01), including weight gain, carapace width gain, and carapace length gain, recorded as 10.28 ± 1.70 g, 0.52 ± 0.03 cm, and 0.41 ± 0.03 cm, respectively. Regarding molting performance, both the molting rate and the average molting interval improved, with shorter molting periods observed particularly in crabs fed with heat-treated eggshell diets. The 25 percent concentration resulted in the highest molting rate and the shortest molting interval (P<0.05), measuring 75.00 ± 5.00 percent and 23.70 ± 7.15 days, respectively. In conclusion, diets supplemented with heat-treated ground eggshell enhanced the growth performance and molting efficiency of rice field crabs, indicating their potential as an effective dietary mineral supplement for the production of soft-shell crab.