The physical and neuromotor development of progeny of female rats fed graded levels of pyridoxine during lactation.

Female rats were maintained throughout gestation on a control diet containing 400% of the National Research Council (NRC) recommendation for pyridoxine and transferred to purified diets containing 400, 100, 75, 50, 25, or 0% of the NRC recommendations for B6 during lactation. Physical development of the offspring was assessed by measuring body weight and the occurrence of physical features, for example: eye opening, eruption of incisors, and growth of the hair to obscure the genitalia. Development of reflex reactions, neuromotor skills and coordination were also observed. Grooming was assessed as a measure of spontaneous activity. Retardation of growth, delay in the onset of reflexes such as palmar grasp, vibrissa placing, visual placing, and audicular startle, and a delay in the onset of advanced neuromotor coordination such as standing and grooming were observed in the pups of pyridoxine-restricted dams. Even progeny of dams, receiving 100% of the NRC recommendations of B6 during lactation exhibited inferior performance of skills requiring advanced neuromotor coordination such as standing, either supported or alone. These animals had weight gains comparable to neonates of maternal animals receiving 400% of the NRC recommendations for pyridoxine. The importance of factors other than growth in the assessment of nutritional requirements is demonstrated.