Evaluation of microbial phytase in broiler diets.
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.
Dilger
R N
RN
Department of Animal Sciences, Purdue University, West Lafayette, Indiana 47907-1151, USA.
Onyango
E M
EM
Sands
J S
JS
Adeola
O
O
D010832:6-Phytase / Q000008:administration & dosage* / Q000235:genetics; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002113:Calcification, Physiologic; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D004032:Diet; D004063:Digestion; D004435:Eating; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D007082:Ileum / Q000378:metabolism; D008903:Minerals / Q000032:analysis; D010758:Phosphorus / Q000378:metabolism; D011994:Recombinant Proteins; D012568:Schizosaccharomyces / Q000235:genetics; D013977:Tibia / Q000737:chemistry; D015430:Weight Gain
D008903:Minerals; D011994:Recombinant Proteins; D010758:Phosphorus; C028705:bone ash; D010832:6-Phytase