QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Momcilovic, B. Search for Related Content PubMed PubMed Citation Articles by Momcilovic, B.

Coupling of Zinc Dose to Frequency in a Regularly Recurrent Pattern Shows a Limited Capacity of Excessive Dietary Zinc to Compensate for a Previously Deficient Intake^1,2,

Berislav Momilovi^3,4,

U.S. Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, ^5,6, Grand Forks, ND 58202

The impact of feeding a proportional dose of zinc in a regularly recurrent pattern (idiorrhythmic feeding) on body growth of weanling rats was studied to assess the extent to which an intake exceeding the requirement could compensate for a previously deficient intake. The idiorrhythmic regimen (I) was designed so that the overall dose-time equivalent (modulo; Mx) was kept constant over a selected period of time (epoch; E), whereas the actual dose and frequency varied regularly according to a predetermined pattern; that is, I = d_nth(Mx)/d_nth, where Mx and d_nth are the selected dose-time equivalent and the sequential number of zinc-dosing days, respectively. For example, 3 mg Zn·kg^-1 diet fed every day (I = 3/1) and 24 mg Zn·kg^-1 diet fed 1 d in an 8-d period (7 d of feeding a zinc-deficient diet) (I = 24/8) are dose-time equivalents because they both provide 72 mg Zn·kg^-1 over a 24-d E. Modulos of M3, M6, M12 and M24 were used, which provided 3, 6, 12 and 24 mg Zn·kg^-1·d^-1 dose-time equivalents during a 24-d E. Each modulo had seven analogous idiorrhythms: I = Mx/1, 2Mx/2, 3Mx/3, 4Mx/4, 5Mx/5, 6Mx/6 and 8Mx/8; for example, with 8 Mx/8, 24, 48, 96 or 192 mg Zn·kg^-1 diet was fed every 8th d; on the other 7 d a diet without a zinc supplement was fed for M3, M6, M12 and M24, respectively. Zinc dose-rate idiorrhythm generated a complex, gestalt-like, biphasic growth response pattern where an intake of dietary zinc exceeding requirements had either no effect (M3 or average of 3 mg kg^-1 diet) or fully compensated for only 1 (M6 and M12 or average of 6 and 12 mg Zn·kg^-1 diet) or 2 (M24 or average of 24 mg Zn·kg^-1 diet) d.

KEY WORDS: • zinc • dose rate • idiorrhythm • growth response • rats

¹ The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 USC section 1734 solely to indicate this fact.

² Presented in part at the Eighth International Symposium on Trace Elements in Man and Animals (TEMA 8), May 1993, Dresden, Germany. Momilovi B. (1993) Idiorrhythmic vs. continuous zinc dietary intake—a model approach to the study of trace element dose-rate impact, abs. 46L and Experimental Biology '94, April 1994, Anaheim, CA. [Momilovi B. (1994) The study of dietary zinc dose-rate (D-R) impact on growth of weanling rats with an idiorrhythmic experimental feeding design. FASEB J. 2: 5429 (abs.)].

³ To whom correspondence should be addressed.

⁴ Visiting research scientist, Institute for Medical Research and Occupational Health, Zagreb, Croatia.

⁵ U.S. Department of Agriculture, Agricultural Research Service, Northern Plains Area is an equal opportunity and affirmative action employer and all agency services are available without discrimination.

⁶ Mention of a trademark or proprietary product does not constitute a guarantee of warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable.

Manuscript received 4 November 1994. Revision accepted 5 June 1995.