PSIII-7 - The Effect of One-carbon Metabolite Supplementation in Combination with Adequate or Restricted Feed Intake During Early Gestation on Maternal Hematology

Abstract: During gestation maternal blood volume increases to meet the needs of the growing fetus. Folate and vitamin B₁₂ are hematopoietic vitamins required for DNA synthesis in developing red blood cells. Our objective was to evaluate the effect of one-carbon metabolites (OCM; folate, vitamin B₁₂, choline, and methionine) supplementation in combination with adequate or restricted intake in early gestation on maternal hematology. Thirty-two cross-bred Angus heifers were estrous synchronized and artificially inseminated with female-sexed semen. At breeding (day 0), heifers were assigned to treatments in a 2 × 2 factorial design. The first factor was control intake (CON; 0.60 kg/day average daily gain) versus restricted (RES; -0.23 kg/day gain). The second factor was OCM supplementation (+OCM; rumen protected choline [0.60 g/day] and methionine [10 g/day] in a fine ground corn carrier and weekly injections of 320 mg folate and 10mg vitamin B₁₂) or no supplementation (-OCM; corn carrier and saline injections). Blood samples were collected on day -2 and day 62 relative to breeding. Samples were analyzed for hematocrit and complete blood cell count with differential. Data were analyzed using the MIXED procedure of SAS with day -2 as a covariate and significance at P < 0.05. Red blood cell count was greater (P = 0.0019) in RES than CON (9.29 vs 8.30 ± 0.186 × 10⁶ cells/mm³). Hematocrit (P = 0.08) and packed cell volume tended (P = 0.09) to be greater in RES than CON. The percentage of monocytes was lower (P = 0.04) in +OCM than -OCM (1.5 vs 3.0 ± 0.50 %). The percentage of segmented neutrophils was greater (P = 0.01) in CON than RES (24.6 vs 16.8 ± 1.93 %). These results indicate that supplementation with OCM did not increase hematopoiesis in early gestation in heifers receiving an adequate or restricted plane of nutrition.