Effect of Dietary Folic Acid Supplementation during Pregnancy on Blood Characteristics and Milk Composition of Ewes

SIMPLE SUMMARY: Folic acid (FA) plays a critical role in regulating fetal development. Cause of the association between maternal metabolism and fetal development has created interest to study FA’s effects on maternal blood metabolism and milk composition. FA was supplemented in the diet of ewes with different litter size during pregnancy and blood parameters, and milk composition was monitored. The results indicated that FA supplementation improved folate metabolism balance during gestation of prolific ewes, and contributed to the ewe’s blood metabolism and health. In addition, immune-related compounds in milk were improved with dietary FA supplementation, thus, the newborn lamb should benefit from the improvement in milk quality. ABSTRACT: The objective of the present study was to investigate the dynamic change of serum parameters and milk composition by dietary FA supplementation with ewes with different litter size from mating to lambing. The ewes were divided into six treatments (TW-CON, TW-F16, TW-F32, TR-CON, TR-F16, TR-F32) according to dietary FA levels (control, CON; 16 or 32 mg·kg(−1) rumen-protect-FA supplementation, F16 and F32) and litter size (twin born, TW; and triplet born, TR). In serum, the concentration of folate increased linearly with dietary FA supplementation (P < 0.05), regardless of the litter size, they showed a quadratic response to gestation progression (P < 0.05). With dietary FA addition, IGFI-I levels significant increased from late gestation to after lambing (P < 0.05), and linearly increased immunoglobulin during the perinatal period (P < 0.05). In colostrum and milk at d 15, the content of folate, lactoferrin, and IgG were affected positively by FA supplementation (P < 0.05). IgG was higher in the TW group than TR in colostrum (P < 0.05), and lactoferrin in TW was lower than TR in milk of d 15 (P < 0.05). FA supplementation increased protein content in colostrum (P < 0.05), while it had no effect on the fat, lactose, and BUN of colostrum and milk of d 15 (P > 0.05). These results suggest that FA supplementation during gestation could regulate maternal blood metabolism and contribute to milk immune composition.