AJP - Endocrinology and Metabolism, Vol 246, Issue 3 221-E226, Copyright © 1984 by American Physiological Society
Vitamin D-deficient rats produce reduced quantities of a nutritionally adequate milk
R. Brommage and H. F. DeLuca
Pups raised by lactating rats deficient in vitamin D do not grow normally,
and we have shown previously that this growth failure results from a
maternal rather than a neonatal defect. This result indicates that vitamin
D-deficient rats produce reduced amounts of milk and/or the milk they do
produce is nutritionally incomplete. To examine the first of these
possibilities, 3H2O and 42K in separate experiments were given to lactating
rats at 13 days postpartum, and the amount of isotope transferred to their
pups during the next 24 h was determined. The amount of milk produced
during this period was calculated from the measured concentrations of 3H2O
and 42K in milk. The specific activity of 3H2O in maternal plasma was kept
constant by providing 3H2O in the drinking water of the dams. Vitamin
D-deficient rats were found to produce only 19.5 +/- 1.8% determined by the
3H2O method and 23.2 +/- 1.1% by the 42K method (means +/- SD) of the
amount of milk produced by vitamin D-replete rats. The composition of milk
from vitamin D-deficient rats was examined to determine its nutritional
value. Vitamin D-deficient milk contains elevated levels of fat, and the
skim fraction contains more protein, potassium, calcium, and inorganic
phosphorus but less carbohydrate than normal milk. When vitamin D-deficient
dams were given two pups to nurse rather than the eight usually provided,
pup growth was equivalent to that of vitamin D-replete pups. Furthermore,
femur dry weights and degree of mineralization were similar in vitamin
D-deficient and -replete pups of equivalent body weight.(ABSTRACT TRUNCATED
AT 250 WORDS)
