The effects of gestational folic acid supplement of sows on offspring immune organ and muscle development and postnatal immune and growth response
Primiparous sows (113 +/- 27 kg BW) were penned individually and fed daily 1.9 kg of a basal, low folic acid diet (.28 mg/kg) supplemented with 0 or 8 mg folic acid from coitus to parturition. All sows were fed the basal diets for 112 days prior to mating to minimize body folic acid (FA) stores. Sows were synchronized and artificially inseminated within sow litter pair to the same boar. Post coitus sows from 19 pairs of littermates were randomly allotted, within litter, to one of the two levels of FA supplementation. At 5 +/- 2 d post-insemination, ovulation rate was determined via laparotomy. At birth, two pigs in each litter were sacrificed. Litters were standardized to 10 +/- 2 pigs and sows were self-fed a nutritionally adequate diet. Sow serum FA concentration, an indicator of body FA stores, declined from 69 to 51 ng/mL during the 112 d depletion period. During pregnancy, serum FA concentration further declined thru mid pregnancy (d 70). Gestational FA supplementation elevated (P < .01) sow serum FA concentration. Gestational FA supplementation did not affect pigs born/litter (8.10 vs. 8.15), litter birth weight (10.49 vs. 11.52 kg), nor pig tissue weight (except visceral organ weight), or DNA and protein content at birth, but did increase (P < .10) litter whole body DNA (30.45 vs 37.85 mg) and protein (1.04 vs 1.28 kg) content at birth. Gestational FA supplementation resulted in a greater percentage of CD2 positive lymphocytes in offspring peripheral blood on d 0 but not d 21 postweaning, resulting in a FA supplementation by day interaction. Gestational FA supplementation also altered (P < .05) lymphocyte blastogenesis rate upon stimulation with PHA in pigs postweaning. Folic acid supplementation of the dam resulted in greater (P < .05) serum agglutination titers in pigs following a secondary SRBC challenge. Folic, acid supplementation did not affect offspring daily BW gain, feed intake, and gain:feed except during the secondary SRBC challenge period. Based on these data, FA supplementation of the gravid dam influenced postnatal immune response of the offspring but not muscle growth in pigs pre- and postnatally.