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

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 d -2 and d 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 d -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 less (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.