AJP - Endocrinology and Metabolism, Vol 239, Issue 2 113-E118, Copyright © 1980 by American Physiological Society
Nitrogen retention during late gestation in the rat in response to marginal zinc intake
S. Greeley, G. J. Fosmire and H. H. Sandstead
This study was conducted to characterize nitrogen retention in response to
marginal dietary zinc during gestation. Long-Evans rats were randomly
assigned to one of two dietary groups on day 1 of gestation. The dams were
fed a basal diet supplemented with either restricted or control levels of
zinc. Feces and urine were collected for 24 h on day 20 of pregnancy, and
their nitrogen and zinc contents were determined. Urinary and fecal
nitrogen excretions were similar for zinc-restricted and control dams,
whereas fecal zinc excretions were depressed by feeding the zinc-restricted
diet. Mean zinc and nitrogen retentions were negative for the
zinc-restricted and positive for the control groups. Multiple stepwise
regression analysis showed that nitrogen retention on day 20 depended on
both dietary nitrogen and zinc intakes. Zinc-restricted offspring weighed
12% less and the maternal plasma zinc concentrations were reduced by 66%
when compared with the control group values on day 22. Marginal dietary
zinc and the associated anorexia limited fetal growth without causing
excessive nitrogen excretion or severe weight loss.
