Untersuchungen zum Einfluß einer unterschiedlichen Riboflavinversorgung während der Laktation auf den Riboflavingehalt von Milch, Leber und Restkörper laktierender Ratten

Abstract

The present study investigated the effect of various dietary riboflavin supplementations (0 to 4000 mg/kg) during lactation on riboflavin concentrations of liver, carcass (bled body without intestine and liver), and milk in the rat. The experiment was conducted until the 14th day of lactation; milk samples were drawn on the 7th and 13th day of lactation. Riboflavin concentrations of milk raised continuously with increasing riboflavin supplementation; in the range between 0 and 10 mg/kg riboflavin supplementation, there was a linear relationship, and in the range between 12 and 4000 mg/kg there was a logarithmic relationship between riboflavin supplementation and riboflavin concentration in the milk. Maximum riboflavin concentration of milk obtained by supplementation with 4000 mg/kg was twelve-fold higher than without riboflavin supplementation. For riboflavin supplementation up to 12 mg/kg, riboflavin concentrations in milk on the 7th day of lactation and that on the 13th day of lactation were not different. In contrast, in rats fed diets with higher riboflavin supplementation, riboflavin concentrations were higher by 25% in average in milk on the 13th day of lactation than in milk on the 7th day of lactation. Contrary to the milk, riboflavin concentrations in liver and carcass exhibited a saturation, which was achieved at a supplementation of 6 mg/kg (liver) and 10 mg/kg (carcass), respectively. Maximum riboflavin concentrations obtained at a supplementation of 4000 mg/ kg were 1.9- and 2.3-fold higher for liver and carcass, respectively, than concentrations obtained without riboflavin supplementation. The dose-response relationship using riboflavin concentrations of liver and carcass as response factors indicates a riboflavin requirement of 8 to 9 mg/kg for lactating rats fed a semisynthetic diet with 17.4 MJ ME/kg dry matter and 20.8% protein in dry matter.

The effect of dietary riboflavin supplementation during pregnancy and lactation on riboflavin concentrations of milk, liver and carcass of lactating rats

“…In the liver and carcass, increasing the riboflavin supplementary level from 5 to 20 mg/kg diet caused only a small increase in riboflavin concentrations. This result agrees with a former study by the authors demonstrating a saturation of riboflavin concentrations in the liver and carcass at a dietary riboflavin concentration of 6 mg/kg diet (R oth ‐M aier et al 1997a). Those results, in agreement with other studies (L eclerc 1979; L eclerc and M iller 1982) show that the riboflavin concentrations of animal tissues are under homeostatic control.…”

“…Contrary to the liver and carcass, the riboflavin concentrations in milk are markedly elevated by increasing the riboflavin supplementation from 5 to 20 mg/kg diet. This result also agrees with other studies showing that the riboflavin concentration in milk can be varied over a wide range by the riboflavin supply during lactation (L eclerc 1979; L eclerc and M iller 1982; R oth ‐M aier et al 1997a). The stage of lactation did not influence the riboflavin concentrations in milk.…”

“…The stage of lactation did not influence the riboflavin concentrations in milk. In agreement with a recent study (R oth ‐M aier et al 1997a), riboflavin concentrations in milk were identical at the 7th and 13th day of lactation. This is in contrast to the thiamin and vitamin B 6 concentrations in milk which both were higher in the later stage of lactation (B enedikt et al 1996; K irchgessner et al 1996; R oth ‐M aier et al 1997b; T rübswetter et al 1997).…”

“…However, there is less information about the riboflavin requirement in particular physiological states such as pregnancy or lactation. A previous study by the authors was conducted to assess the riboflavin requirement during lactation based on the determination of the crythrocyte glutathione reductase activity coefficient and riboflavin concentrations in the liver and carcass (H irschvogl et al 1997; R oth ‐M aier et al 1997a).…”