Evaluation of microbial phytase in broiler diets

• Published in: Poultry science 2004-06, Vol.83 (6), p.962-970
• Main Authors: Dilger, R.N, Onyango, E.M, Sands, J.S, Adeola, O
• Format: Article
• Language: English
• Subjects: 3-phytase; 4-phytase; 6-Phytase - administration & dosage; 6-Phytase - genetics; Animal Nutritional Physiological Phenomena; Animals; ash content; bioavailability; broiler chickens; broiler feeding; Calcification, Physiologic; Chickens - growth & development; Chickens - physiology; Diet; digestibility; Digestion; Eating; enzyme activity; Escherichia coli - enzymology; Escherichia coli - genetics; excretion; feed additives; feed conversion; feed intake; grower diets; Ileum - metabolism; liveweight gain; Minerals - analysis; mortality; nutrient management; nutrient retention; phalanges; phosphorus; Phosphorus - metabolism; Recombinant Proteins; Schizosaccharomyces - genetics; starter diets; tibia; Tibia - chemistry; Weight Gain
• ISSN: 0032-5791; 1525-3171
• DOI: 10.1093/ps/83.6.962

Two trials were conducted to evaluate the efficacy of a new microbial phytase (Phyzyme XP) for broiler chicks. Trial 1 used 192 8-d-old male broilers in a 14-d trial to assess growth and nutrient utilization. Dietary treatments (221.9 g/kg CP) included a positive control [5.0 g/kg nonphytate P (NPP)], negative control (1.2 g/kg NPP), and negative control plus 500 or 1,000 phytase units/kg of diet. Phytase addition increased weight gain, feed intake, feed efficiency, and tibia and toe ash (linear, P < 0.01) with tibia ash also responding quadratically (P < 0.05). Apparent ileal digestibility of P (linear and quadratic, P < 0.05), tryptophan, and valine (linear, P < 0.05) also increased. Linear and quadratic responses were observed for retention of DM, nitrogen, P, and several amino acids (P < 0.05) with added phytase. Trial 2 utilized 576 1-d-old male broilers over a 42-d period to evaluate growth performance. Diets were formulated for starter (222.7 g/kg CP) and grower (201.5 g/kg CP) phases and included a positive control (starter and grower, 5.0 and 3.8 g/kg NPP, respectively); negative control (starter and grower, 2.4 and 1.8 g/kg NPP, respectively); negative control plus 500, 750, or 1,000 phytase units/kg; and negative control plus 500 phytase units/kg of Natuphos phytase. Phytase increased weight gain and feed intake (starter, grower, overall) as well as feed efficiency during the starter period (linear, P < 0.05). Feed intake was also improved during the grower period and overall (quadratic, P < 0.05). Tibia and toe ash of birds fed for the first 21 d increased (linear, P < 0.05) with tibia ash also increasing quadratically (P < 0.05). Overall, tibia and toe ash were improved due to phytase addition (linear and quadratic, P < 0.05). In conclusion, this microbial phytase, derived from Escherichia coli and expressed in Schizosaccaromyces pombe, elicited improved growth performance, bone mineralization, and P utilization in broiler chicks.