Bioavailability of feed grade calcium phosphate incorporated into practical diets for Penaeus vannamei |
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| Authors: | D Allen Davis & CR Arnold |
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| Institution: | The University of Texas at Austin, Marine Science Institute, Port Aransas, Texas, USA |
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| Abstract: | Practical diets designed for penaeid shrimp are commonly supplemented with phosphorus, which may lead to unnecessary nutrient loading of the culture system and effluent waters as well as unnecessary investments in a nutrient that is not utilized by the culture species. To facilitate the optimization of phosphorus levels in practical shrimp feeds, research was conducted with Penaeus vannamei juveniles to determine the biological availability of two feed-grade calcium phosphate sources. A practical basal diet containing 350 g protein kg?1 diet and 9.8 g P kg?1 diet was formulated using anchovy and soybean meal as the primary protein and phosphorus sources. The basal diet was supplemented with graded levels of phosphorus and offered to juvenile shrimp (0.57 ± 0.017 g) over a 10-week period. Weight gain and estimated feed efficiency values increased with phosphorus supplements, indicating a dietary deficiency of the basal diet. Under the reported conditions, a dietary supplement of 1.4 or 2.3 g P kg?1 diet was required for maximum growth and estimated feed efficiency values if Cefkaphos (primarily monobasic calcium phosphate) or Dynafos (primarily dibasic calcium phosphate) was utilized. Dynafos was determined to have a relative biological value (RBV) of 63.8% of Cefkaphos based on final weights of the shrimp offered diets containing 1.25 g supplemental P kg?1 diet. A similar RBV of 60.9% was estimated based on broken-line analyses of growth data. There were no significant differences in apparent net phosphorus retention (ANPR) for the basal diet (23.1%) or diets supplemented with 1.25 g P kg?1 diet originating from Cefkaphos (25.7%) or Dynafos (17.9%). However, shifts in ANPR values of the diets corresponded to biological availability of the two phosphorus sources. |
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| Keywords: | Penaeus vannamei phosphorus nutrition |
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