Efficacy of an Escherichia Coli Phytase for Improving Mineral Utilization in Pigs and Chickens
A number of experiments were conducted to determine the phosphorus (P)-releasing efficacy of a new E. coli-derived phytate, (EcoPhos(TM), Phytex LLC, Portland, ME) expressed in yeast for both young chickens and pigs using standard-curve methodology. This phytate, was cloned from an E. coli strain isolated from pig colon and it exhibited low amino acid sequence homology to the A. ficuum phytate, (Natuphos RTM, BASF, Mt. Olive, NJ), low pH optimum (2.5 to 3.5), low K m for sodium phytate, and a high degree of resistance to the gastric protease pepsin (cf. Rodriguez et al., 1999). Linear (P < 0.01) responses in chick or pig growth performance and bone ash values to supplemental inorganic P (iP) were found in all standard-curve assays. In each assay, chicks fed P-deficient corn-soybean meal (SBM) diets supplemented with EcoPhos(TM) had greater (P < 0.01) growth performance and bone ash values than those supplemented with NatuphosRTM or RonozymeRTM (Roche, Parsippany, NJ) at similar activity levels. Overall, EcoPhos(TM) at 500 phytate, units (FTU)/kg released approximately 0.13% P, compared with P-release values of approximately 0.04% for the other two phytases, relative to monobasic potassium phosphate. In young pigs, 400 FTU/kg of EcoPhos(TM) released 0.11% P, compared to P-release values of 0.08 and 0.04% for NatuphosRTM and Ronozyme RTM, respectively. EcoPhos(TM) (500 FTU/kg) also released approximately 0.09% calcium (Ca) in chicks fed Ca-deficient corn-SBM diets. Supplemental EcoPhos(TM) at 10,000 FTU/kg was found to be efficacious and safe for growing-finishing pigs and second-cycle laying hens fed P-deficient corn-SBM diets. In fact, 250 FTU/kg in pigs and 150 FTU/kg in laying hens produced responses that were similar (P > 0.10) to that from 0.10% iP supplementation. Utilization of standard-curve methodology showed that 5,000 and 10,000 FTU/kg of EcoPhos(TM) produced bone ash responses that were greater ( P < 0.05) than those obtained with 0.20% iP supplementation. The latter results suggested that between 70 to 100% of P in corn- and SBM-derived phytate was released. The P-releasing efficacy of EcoPhos(TM) was reduced (P < 0.05) approximately 30% by 1,500 mg/kg of supplemental Zn. These data show that EcoPhos(TM) markedly improves P bioavailability in pigs and chickens.
Agriculture, Animal Culture and Nutrition
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign