PHYTASE FORTIFICATION OF A COMMERCIAL CATFISH DIET ELEVATES MINERAL STORES AND IMPROVES HEMATOLOGICAL HEALTH OF CHANNEL CATFISH, Ictalurus punctatus  

James Mazzola, Benjamin H. Beck, and Eric Peatman*
 
Auburn University School of Fisheries, Aquaculture, and Aquatic Sciences,
Auburn, AL, USA
peatmer@auburn.edu

Phytic acid is a central inhibitor of iron absorption in plant-based fish diets and a potential contributor to chronic low grade anemia.  Phytic acid levels in catfish diets have risen along with inclusion percentages of certain ingredients such as wheat middlings.  While previous phytase studies in catfish have demonstrated improved growth and phosphorus retention, the impact of the enzyme on iron retention and hematological traits has not been examined.  Accordingly, the impact of phytase superdosing (2500 FTU/kg) in a commercially-available catfish diet was evaluated in channel catfish (Ictalurus punctatus) fingerlings.  Catfish fed phytase-supplemented diets had higher mineral levels (including iron) in serum and liver along with improved hematocrit, hemoglobin, and red blood cell values. Weight gain and feed conversion ratios were also significantly improved in the 15 week replicated pond study.   Results from the present study indicate that addition of phytase to commercial catfish diets may have measurable impacts on fish health and performance.