AN ASSESSMENT OF DIETARY FOLIC-ACID LEVELS DURING GESTATION AND LACTATION ON REPRODUCTIVE AND LACTATIONAL PERFORMANCE OF SOWS - A COOPERATIVE STUDY

Crossbred female swine (n = 393) were used in a multiparity study at f ive experiment stations to evaluate the effects of dietary supplementa tion of folic acid (FA) on serum folates status and reproductive perfo rmance. The dietary treatments were a corn-soybean meal basal diet (ca lculated FA, .34 ppm) supplemented with 0, 1, 2, or 4 ppm FA. Experime ntal diets were fed continuously from a minimum of 21 d before first,m ating throughout the entire study. At one station, blood samples for r adioimmunoassay determination of serum folates concentration were coll ected by vena cava puncture at mating, d 55 of gestation, d 110 of ges tation, and at weaning. Stage of reproduction and dietary FA supplemen tation affected (P < .005) serum folates concentrations. Serum folates declined from mating to d 55, remained low at d 110, and returned to higher levels at weaning. Linear increases (P < .001) in serum folates with increasing level of dietary FA were observed at each reproductiv e stage. Over the course of the study, reproductive performance criter ia including total pigs born, live pigs at birth and d 21, and individ ual pig and Litter weight at birth and d 21 were not affected (P > .10 ) by inclusion of FA in the diet. The number of days postweaning to es trus also was not affected by FA treatment. Under the conditions of th is experiment, increasing level of FA in the diet had a pronounced eff ect in attenuating decreased serum folates concentration during gestat ion but was without benefit to reproductive performance.