Influence of Dietary Pyridoxine on Lactation in the Rat

Abstract

The effects of deficient and adequate amounts of dietary pyridoxine on milk yield and composition were studied in the rat. Following mating, Sprague-Dawley strain rats were fed ad libitum either a pyridoxine-free diet (deficient) or a diet containing 20 mg pyridoxine·HCl/kg (control). A third group of rats, restricted control, were fed the control diet limited in quantity to that consumed by the deficient group. Litters were adjusted to six pups and remained with natural dams, except in one experiment in which deficient pups were cross-fostered to control dams and control pups to deficient dams from day 6 of lactation. Restricted-control dams had reduced milk yields on day 10 compared to controls; yields for deficient dams were less than those for either control or restricted-control dams. Milk yields for deficient dams in cross-fostered groups were similar to those for control dams indicating that low yields of deficient dams were due primarily to the inability of their young to suckle. Vitamin B-6 concentration in stomach contents of pups from deficient dams was markedly less than that for control or restricted-control groups. Administration of a nonmetabolizable amino acid analog, 14C-α-aminoisobutyric acid, indicated no differences in amino acid transport in liver, muscle, or mammary gland among the groups. The lower tissue to serum ratios of the analog in functioning mammary gland of the deficient group was attributed to the vitamin deficiency and to reduced milk synthesis. Administration of growth hormone to dams during lactation did not influence any of the parameters studied.