Phytase effects on the efficiency of utilisation and blood concentrations of phosphorus and calcium in Pekin ducks

Markus Rodehutscord (1) , Romy Hempel , Peter Wendt

1 Institut fuer Ernaehrungswissenschaften

1. The objective was to study the effects of a supplementation of a 6-phytase derived from the Peniophora lycii gene in the White Pekin duck. 2. In two balance studies, low-P diets were supplemented with phytase up to levels of 1,500 U/kg (Study 1) and 2,000 U/kg (Study 2). Each diet was fed to 8-10 individually penned ducks. The intake and excretion of each animal was measured for five consecutive days when ducks were in their third week of life. Responses were described by nonlinear regression. 3. Efficiency of P utilisation (P accretion/P intake × 100) for the unsupplemented basal diets was 39% in Study 1 and 30% in Study 2. Phytase supplementation significantly improved P utilisation up to levels of about 55% in both studies. A plateau in P utilisation with an increase in phytase supplementation was achieved in Study 2, but not in Study 1. The enzyme was more efficient in Study 2 than in Study 1 at low levels of supplementation. Accretions of P and Ca increased at a constant ratio. 4. In a five-week growth study, diets with an intentionally marginal P level were used. Diets were fed either unsupplemented or supplemented with 1,000 or 10,000 U/kg. Eight pens of ten sex-separated ducks each (four pens per sex) were allocated to each dietary treatment. 5. Phytase significantly improved the growth of ducks in both sexes between days 1 and 21, but not between days 22 and 35. The feed conversion rate was not affected. Blood serum phosphate concentrations were significantly improved by phytase supplementation. Blood concentrations of creatinine, aspartate aminotransferase, and lactate dehydrogenase remained unaffected while alanine aminotransferase was significantly reduced by phytase supplementation. 6. It was concluded that the efficacy of a microbial phytase varies even under similar experimental conditions. This 6-phytase has the potential to improve the utilisation of plant P in duck feeding. In response, a plateau was reached above 1,500 U/kg.

Mots clés: Life Sciences

Markus Rodehutscord, Romy Hempel, Peter Wendt. Phytase effects on the efficiency of utilisation and blood concentrations of phosphorus and calcium in Pekin ducks. British Poultry Science, 2006, 47 (03), pp.311-321. ⟨10.1080/00071660600732353⟩. ⟨hal-00545297⟩