Optimization of Calcium and Phosphorous Ratio in the Practical Diet of Hypophthalmichthys molitrix.

An experiment of 90-days was performed to investigate the effects of dietary calcium (Ca), phosphorus (P) and their interaction on growth, whole-body composition, nutrient digestibility and mineralization of silver carp, Hypophthalmichthys molitrix (average initial weight 13.7 ± 0.05 g). Nine isonitrogenous, isocaloric and isolipidic diets with three Ca levels (0, 1 and 2%) combined with three P levels (0, 1 and 2% P) were prepared. Results showed that silver carp fed the diet supplemented with 1% Ca and 1% P level yielded the similar (p > 0.05) growth performance as was recorded for that fed diet containing 2% Ca and 2% P. No significant difference in survival rate was recorded except for the diet containing 1% Ca with 2% P supplement. The feed intake (FI) of juvenile remained unaffected (p > 0.05) by mineral supplementation. Whole body protein content increased (p < 0.05) slightly with Ca and P supplementation. However, moisture, fat and ash contents remained unaffected (p > 0.05). Dietary Ca and P supplementation improved (p < 0.05) the protein and fat digestibility in silver carp. Ca and P contents showed significant increase (p < 0.05) with increasing Ca and P levels in the whole body, bones and scales, achieving the highest (p < 0.05) values at 2% Ca supplemented with 2% P. Whereas, Mg and Zn contents decreased (p < 0.05) with increasing Ca and P supplementation. Fish fed the diet containing 2% Ca level without P supplement had higher (p < 0.05) Ca/P ratio in whole body and bones. However, it decreased (p < 0.05) at 2% Ca level in scales. Further, increase in P supplementation significantly reduced (p < 0.05) Ca/P ratio regardless of Ca level. Conclusively, supplementation of 1% Ca in the presence of 1% P (1:1 ratio) is required for optimum performance of silver carp. [ABSTRACT FROM AUTHOR]