THE EFFECT OF DIETARY RIBOFLAVIN SUPPLEMENTATION DURING PREGNANCY ANDLACTATION ON RIBOFLAVIN CONCENTRATIONS OF MILK, LIVER AND CARCASS OF LACTATING RATS

The aim of the present study was to investigate the effect of riboflav in supply during pregnancy and lactation on the riboflavin status of r ats after pregnancy and lactation. Therefore, an experiment with a tot al of 81 female rats was conducted. The effect oi riboflavin supplemen tation during pregnancy on riboflavin status after pregnancy was inves tigated by feeding diets with various riboflavin supplements (1, 5 or 20 mg riboflavin per kg diet) and the determination of riboflavin conc entrations in liver and carcass (bled whole body without intestine and liver). The study shows a marked influence of dietary riboflavin supp lementation during pregnancy on riboflavin concentrations of liver and body after pregnancy. Liver exhibited maximum riboflavin concentratio ns at a supplementary level of 5 mg/kg diet whereas riboflavin concent rations in the carcass were raised by increasing the supplementary lev el from 5 to 20 mg/kg diet, The riboflavin status after lactation has been studied in response to the riboflavin supplementation during preg nancy (1 or 20 mg/kg diet) and lactation (1, 5 and 20 mg/kg diet). Ln order to assess the riboflavin status, riboflavin concentrations in th e liver and carcass (at the 14th day of lactation) and milk (7th and 1 3th day of lactation) were determined. The study shows that the ribofl avin concentrations of all the samples are influenced predominately by the riboflavin supply during lactation; the riboflavin supply during pregnancy had only a slight effect on the riboflavin concentrations of milk, liver and carcass. Moreover, the riboflavin concentration in mi lk was more influenced bf the riboflavin supply during lactation than the riboflavin concentrations of the liver and carcass. Increasing the riboflavin supplementation during lactation from I to 20 mg/kg diet c aused a five-fold increase of riboflavin concentrations in milk, where as riboflavin concentrations in the liver and carcass increased only b y approximate to 80%. Those results demonstrate that the riboflavin co ncentration in milk ran be varied over a wide range by the riboflavin supply during lactation whereas the riboflavin concentrations of tissu es are under homeostatic control. Moreover, the study shows thar a hig h riboflavin supply during pregnancy cannot compensate for a deficient supply during lactation. Therefore, particular attention has to be gi ven to the dietary riboflavin supply during both physiological states.