Effects of different calcium levels on growth, survival rate and production of snail (Pila polita) in grow-out period

Abstract

In this study, different calcium levels in the diet were fed in the grow-out period to evaluate the growth and survival rate of black apple snail (Pila polita). There were 5 treatments and 3 replicates in each treatment and the snails were fed with different calcium levels at 1% (Ca1); 3% (Ca3); 5% (Ca5); 7% (Ca7); 9% (Ca9). Two-month-old juveniles with initial body weight, shell height and shell width of 2.13 g, 21.71 mm and 16.35 mm, respectively were reared in the tarpaulin tanks (1 × 1 × 1 m; 40 cm water depth) at the density of 100 inds/tank. After 4 months of rearing period, the average body weight, shell height and shell width of the snail reached the highest value in Ca5 (28.43 g; 54.97 mm; 40.09 mm, respectively) and that was significant difference (p<0.05) compared to the remaining calcium contents. The survival rate of snails in Ca3 (75.7%) was higher than in Ca1, Ca5, Ca7, and Ca9. However, the survival rate was not significant difference among treatments (p>0.05). Snails in Ca5 obtained the highest productivity (2.88 kg/m2) compared to Ca3 and Ca7, and that was significant difference (p<0.05) compared to Ca1 or Ca9. The results of this study showed that the growth rate and productivity of black apple snail were highest when the feeding diet contained 5% calcium.