THE EFFECT OF DIFFERENT RIBOFLAVIN SUPPLE MENTS DURING PREGNANCY AND LACTATION ON PERFORMANCE AND ERYTHROCYTE GLUTATHIONE-REDUCTASE ACTIVITY OF RATS

In two experiments with 160 female Sprague-Dawley rats the influence o f various dietary riboflavin supplementations during lactation and dur ing pregnancy and lactation were examined on food intake, body mass, r eproduction, hematologic profile and the erythrocyte glutathione reduc tase activity coefficient (EGR-AC). In the first trial rats were fed a semisynthetic, riboflavin-deficient diet, based on casein and corn st arch with various riboflavin supplementations during lactation (0, 2, 4, 6, 8 10, 12, 40, 400, 4000 mg riboflavin/kg diet). In the second ex periment the rats received supplements of 1 and 20 mg riboflavin/kg di et, respectively, during pregnancy. After parturition each group was d ivided into three sub-groups with riboflavin supplementations during l actation of 1, 5 and 20 mg/kg diet, respectively. Both investigations ended at the 14th day of lactation. Food intake was decreased signific antly by 25 % and 11 % in the groups without riboflavin supplementatio n or 1 mg riboflavin/kg diet. In the same groups body mass was reduced by 11 % and 4 %, respectively. With regard to the reproduction parame ters the riboflavin supply influenced only the litter mass at the 14th day of lactation and only lactational supply was relevant. In both tr ials the results of the hematologic profile showed no differences. In riboflavin deficiency (0 or 1 mg riboflavin/kg diet, respectively) the EGR-AC was increased significantly to 1.9 and 1.8, respectively. At t he supplementation of 4-5 mg riboflavin/kg diet EGR-AC reached a plate au of 1.45, which was not improved by higher supplements. Concerning t he whole reproduction cycle (trial II) there was a stronger influence of the actual lactation-supply on EGR-AC, on the other hand a riboflav in deficiency in pregnancy could be compensated only partially by an o ptimal supply in lactation. Therefore, based on the parameter EGR-AC a n optimal riboflavin supply is recommended for each part of the reprod uction cycle. By means of EGR-AC also the riboflavin requirement for l actating rats was derived. Feeding a semisynthetic diet (17.4 MJ ME/kg DM, 20,8 % crude protein in DM) a supplementation of 5-6 mg riboflavi n/kg or a total content of 6-7 mg/kg diet is recommended.