Phosphorus equivalence of a Consensus phytase produced by Hansenula polymorpha in diets for young turkeys

An experiment was conducted to determine the efficacy of a so-called consensus phytase preparation produced by Hansenula polymorpha on growth, tibia and toe ash and P retention of young turkeys. A total of 192 female turkeys ( BUT 9 strain) were placed into 96 batteries at two per cage and assigned to one of eight diets: A negative control containing 2.5 g non-phytate P per kg feed (T-1); T-1 plus 125, 250, 500, 1000 or 10 000 phytase units ( U) per kg feed, respectively, (T-2 to T-6); T-1 plus 0.5 or 1.0 g P-i/kg feed as dicalcium phosphate dihydrate (DCP), respectively, (T-7 and 8). The experiment lasted 32 d, and excreta were collected and weighed between 26 and 29 d of age. Feed was also weighed during this period in order to calculate P retention. Performance was calculated for the 0 to 32 d period. At the end of the experiment one bird per pen was killed for tibia and toe ash content determination, except for T-2, T-3, and T-7. Body weight, FCR, toe and tibia ash, and P retention responded to phytase or P-i supplementation. Using linear or quadratic models for comparing performance of the treatments containing supplemental P-i with phytase treatments, an equivalence between phytase and P-i was calculated. Body weight, toe ash, tibia ash and P retention showed a significant response to phytase supplementation. The values of equivalence for body weight, toe ash, tibia ash and P retention were 251, 597, 391 and 390 U to 1 g P-i/kg feed. At 10 000 U/kg feed there was a significant response in terms of weight gain and P retention, indicating that turkeys respond to levels greater than 1 000 U/kg feed.