The effect of dietary phytase on growth performance and phosphorus utilization of broiler chicks.
1993
Perney K.M. | Cantor A.H. | Straw M.L. | Herkelman K.L.
Two experiments were conducted to evaluate the effect of dietary phytase and increasing levels of available phosphorus [P(av)] on the growth performance and phosphorus metabolism of broiler chicks. In both experiments, graded levels of P provided by dicalcium phosphate and of phytase were added to a low-P corn-soybean meal basal diet. In Experiment 1, diets providing.21,.29,.37, and.44% P(av) without phytase;.21% P(av) plus.05,.10, or.30% phytase; and.29% P(av) plus.10% phytase were each fed to four groups of seven chicks, 3 days of age. In Experiment 2, diets providing P(av) levels of 32,.38, and.44% and phytase levels of.9, 1.0, and 1.5% (250,500, and 730 units/kg) in a factorial arrangement were each fed to four groups of eight chicks, 5 days of age. In Experiment 1, increasing dietary P(av), but not phytase, increased feed intake, weight gain, feed conversion, plasma inorganic P, tibia and toe ash and tibia breaking strength (P less than or equal to.05). Plasma inorganic P responded quadratically to increasing dietary phytase. In Experiment 2, feed intake and weight gain were increased by elevating the level of P(av), but not by phytase. Toe and tibia ash and plasma inorganic P were increased by dietary phytase and increasing levels of P(av) (P less than or equal to 0.01). Tibia breaking strength was improved (P less than or equal to 0.05) by dietary phytase but not by increasing levels of P(av). The P excretion was elevated (P less than or equal to 0.01) by increasing levels of P(av) and was decreased by supplemental phytase (P less than or equal to 0.05). Dietary phytase added to diets low in P(av) was able to improve some, but not aH variables studied.
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