Serum and milk folates during the first two gestations and lactations in Romanov, Finnsheep, and Suffolk ewes.

Concentrations of folates in serum and milk were determined during the first two parities in 7 Suffolk, 12 Finnsheep, and 15 Romanov ewes at 0 (mating), 60, 110, and 140 d of gestation and 1, 7, 14, 21, and 50 d of lactation. The number of lambs born at first and second parturitions was 1.38 +/- .13 and 1.71 +/- .13 for Suffolk, 2.00 +/- .32 and 2.33 +/- .57 for Finnsheep, and 2.67 +/- .24 and 3.20 +/- .22 for Romanov, respectively, and the concentration of folates at d 0 was 1.17 +/- .21, 1.87 +/- .19, and 2.14 +/- .17 ng/mL, respectively. During gestation, serum concentrations of folates declined in the three breeds, more quickly in Romanov and Finnsheep (from d 0 to 60) than in Suffolk (from d 0 to 110). This decline was followed by an increase in serum concentrations of folates from d 110 to 140 of gestation in the three breeds; the largest increase was observed in Romanov (breed x quadratic effect of time, P = .001). During lactation, Romanov had higher serum concentrations of folates than Finnsheep, which in turn had a higher concentration than Suffolk (P = .001). Colostrum of Romanov had the highest concentration of folates (164.9 +/- 11.9 ng/mL), followed by that of Finnsheep (125.0 +/- 9.5 ng/mL) and Suffolk (98.2 +/- 13.3 ng/mL). On d 7 of lactation, concentration of folates was similar in milk of Romanov (97.1 +/- 5.6 ng/mL) and Finnsheep (94.9 +/- 4.0 ng/mL) and was higher than in Suffolk (72.4 +/- 3.7 ng/mL). From d 14, the concentration of milk folates was similar among breeds and decreased slowly to approximately 40 ng/mL at d 50 (breed x quadratic effect of time, P = .005). The changes in serum concentration of folates during gestation of ewes were similar to those observed in sows, suggesting that exogenous supply of folates may not be optimal in ewes during gestation and lactation.