Folic acid supplementation to diets of gestating-lactating swine over multiple parities.

Crossbred gilts (n = 59) were utilized in a three-parity study to evaluate the effects of dietary additions of folic acid for reproducing swine and to ascertain if responses were dependent on the presence of a sulfonamide in the diet. The four dietary treatments were 1) control, a 14% crude protein corn-soybean meal diet with 110 ppm tylosin, 2) diet 1 plus 110 ppm sulfamethazine, 3) diet 1 plus 1 ppm folic acid and 4) diet 2 plus 1 ppm folic acid. Gilts were allotted to dietary treatment based on age, weight and ancestry within 15 d postbreeding and remained on the assigned dietary treatment continuously. Folic acid supplementation of the diet improved (P less than .05) total (11.17 vs 10.23) and live pigs born (10.79 vs 9.86) per litter; however, when litters were weaned at 28 d, the folic acid advantage was not significant (P greater than .20, 9.34 vs 9.03). No dietary effects (P greater than .10) were observed for pig birth weight or weaning weight. Number of breedings required per female farrowed tended (P less than .12) to be less for females fed folic acid-supplemented diets (1.07 vs 1.16). These results demonstrate improved sow performance through an increase in pigs born and possibly an improved conception rate when folic acid is supplemented to cornsoybean meal diets.