[The effect of a supplement of microbial phytase on zinc availability].
A study of 35 (5 x 7) male, individually housed, albino rats (initial average weight = 50 g) was undertaken to examine the effect of an addition of microbial phytase to a diet containing phytate on the availability of zinc. The rats were fed a semisynthetic diet based of egg white and cornstarch over a 3-week period. All diets were supplemented with 20 mg Zn/kg. Group I (control) was fed the basal diet free of phytic acid (PA) and phytase. By replacing cornstarch by Na-phytate (0.5% in group II and 1.0% group III), molar phytate: Zn ratios of 25 and 50:1 were obtained, respectively. In groups IV (0.5% PA) and V (1.0% PA) 1000 U of microbial phytase were added. A molar phytate:Zn ratio of 25 (group II) and 50:1 (group III) resulted in a dose-dependent depression of growth and feed efficiency ratio. These negative effects of the addition of PA could be completely counteracted by the supplementation of 1,000 U of phytase in group IV and partially so in group V. Similarly, the apparent absorption and retention of Zn, Zn-concentration in femur and testes and different Zn-status-parameters in plasma (Zn-concentration, percent unsaturated plasma-Zn binding capacity, activity of alkaline phosphatase) were improved by adding 1,000 U microbial phytase/kg diet. The present study shows that an addition of microbial phytase to phytate-rich diets considerably improves the availability of Zn in growing rats.
Rimbach
G
G
Institut für Tierernährung, Justus-Liebig-Universität Giessen.
Pallauf
J
J
D010832:6-Phytase / Q000008:administration & dosage / Q000378:metabolism*; D000042:Absorption; D000818:Animals; D001682:Biological Availability; D004305:Dose-Response Relationship, Drug; D005527:Food, Fortified; D008297:Male; D010833:Phytic Acid / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D015430:Weight Gain / Q000187:drug effects; D015032:Zinc / Q000493:pharmacokinetics*
D010833:Phytic Acid; D010832:6-Phytase; D015032:Zinc
Effekt einer Zulage mikrobieller Phytase auf die Zinkverfügbarkeit.