| To study the proper addition and the nutritional function of VD, different concentrations of VD (0—240 IU/g) were used to feed P. chinensis in this experiment. The test shrimps were 8cm length and 7g weight in average and were cultured for 35 days.
It was found that by addition of 6 000IU of VD per 100g to diets, the rates of increase of shrimp length and weight were the largest, the digestion of protein was the best, and the feed coefficient was the lowest. It was also found that VD had no obvious effect on the survival rate of shrimps.
The experiment showed that different levels of VD affected the amount of some mineral absorbed and deposited by the shrimp. Higher VD concentration helped absorption of phosphorus, lower concentration helped absorption of calcium, so proper VD content in the diets can help the shrimps to absorb calcium and phosphorus and promote hardening of shrimp shells. |
