COMPARATIVE EFFICACY OF VARIOUS PHOSPHATE SOURCES OF THE GROWTH PERFORMANCE, PHOSPHORUS RETENTION AND DIGESTIBILITY IN WHITELEG SHRIMP Litopenaeus vannamei

A study was undertaken to evaluate the effect of three supplemental phosphate sources, Windmill® Aquaphos (MAP), monopotassium phosphate and monocalcium phosphate on the growth performance, whole-body phosphorus (P) and calcium (Ca) retention, P and Ca digestibility on whiteleg shrimp Litopenaeus vannamei.

Material and Methods

Quintuplicate groups of 25 shrimps, were fed one of the experimental diets during 54 days. At the start of the trial, a pool of 25 whole shrimp from the initial stock and a pool of 10 whole shrimp per tank at the end of the trial, were sampled for analysis of whole-body protein, ash, phosphorus and calcium content. To determine the digestibility, yttrium oxide was added to the experimental diets as an indigestible marker. Faeces were collected by means of syphoning.

Results & Discussions

Final body weight (FBW, g) ranged between 8.00 and 13.70 g. FBW and specific growth rate (SGR. %/d) of shrimp fed the NC diet was significantly lowest among all diets. Shrimp fed the MAP showed a significantly higher FBW and lower FCR than other diets. During the entire trial, the survival rate ranged between 97.6 and 99.2%.

The whole-body composition of shrimp in terms of protein, P and Ca was significantly affected by the various dietary treatments. The retention of P (expressed as % of intake) was significantly higher for MAP group. This resulted in a higher P-retention of the phosphate source for MAP (39,8%) compared to MCP (28,5%) and MKP (23,3%).

Shrimp fed phosphate without Ca (MAP and MKP) presented calcium retention values higher than 100%, suggesting absorption of calcium from the surrounding water. While the diet containing MCP resulted in a significant lower calcium retention. In other words, there is no need to add Ca via feed ingredients. It has even a negative effect on nutrient retention.

When calculating the digestibility of phosphorus (ADC), MAP showed the highest results which was significantly higher than that of MCP and MKP (P<0.001).

The overall experimental data demonstrates that Windmill® Aquaphos is an effective strategy to enhance growth performance, phosphorus digestibility and retention in whiteleg shrimp (Litopenaeus vannamei).