Fortification of commercial catfish rations with superdoses of phytase enzymes increases hematological parameters and mineral stores in channel catfish (Ictalurus punctatus) and hybrid catfish (Ictalurus punctatus x Ictalurus furcatus)

Abstract

Phytic acid is a well-known antinutritional factor and readily binds to di and trivalent ions reducing their bioavailability and thus absorption by the animal. Phytic acid levels in catfish diets have risen along with inclusion percentages of certain ingredients such as wheat middlings. While some of these ingredients contain phytase, the concentration of phytic acid may still inhibit mineral absorption. Accordingly, the impact of phytase superdosing (2500 FTU/kg) in a commercially available catfish diet was evaluated in channel catfish (Ictalurus punctatus) and hybrid catfish (channel x blue) fingerlings at the USDA-ARS in Stuttgart, AR and Auburn University. 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 studies.