72 Effects of Differing Planes of Nutrition and one-Carbon Metabolite Supplementation of Beef Heifers on B12, Folate, and Folate Intermediate Concentrations in the dam and Fetus
Authors: Syring Jessica , Crouse Matthew S , Entzie Yssi , King Layla , Hirchert Mara , Ward Alison K , Lee Robert , Reynolds Lawrence P , Borowicz Pawel P , Dahlen Carl R , Caton Joel S 
Published: October 2023

Abstract
Vitamin B12 and folate are involved in the metabolic process known as one-carbon metabolism, which among other things, has a role in DNA, RNA, and protein methylation. This methylation connects one-carbon metabolism to epigenetics, which influences fetal development. Thus, an adequate supply of one-carbon metabolites (OCM) is important during fetal development. We hypothesized that differing planes of nutrition, along with supplementation of OCM, would impact concentrations of B12, folate, and folate intermediates in maternal liver, maternal serum, fetal liver, allantoic fluid (ALF), and amniotic fluid (AMF). Specifically, OCM supplementation would increase circulating and hepatic B12 and folate concentrations compared with non-supplemented heifers. Heifers (n = 72) were individually fed on one of two planes of nutrition: control (CON; 0.45 kg/d gain) or restricted (RES; -0.23 kg/d gain). To complete the 2 × 2 factorial arrangement, heifers were also given either OCM supplementation (10 g/d rumen-protected methionine + 60 g/d rumen-protected choline in the diet plus 20 mg B12 + 320 mg folic acid; weekly intramuscular injections) or no supplementation (grain carrier + saline injection). Thus, the final treatments were CON-OCM, CON+OCM, RES-OCM, and RES+OCM. Heifers were bred to a single sire via artificial insemination with sexed semen. Heifers pregnant with female calves (n = 31) were selected for slaughter on d 63. Samples of maternal liver, ALF, AMF, and fetal liver were collected at slaughter. Maternal serum was collected at breeding (d 0) and at slaughter. For B12 and folate concentration analysis, maternal serum was sent to IDEXX BioAnalytics (N. Grafton, MA). For analysis of folate intermediate concentrations in maternal and fetal liver, ALF, and AMF, samples were analyzed using LC-MS/MS. There were treatment × day interactions (P ≤ 0.05) for B12 and folate in maternal serum; on d 63, R+OCM was greater compared with C-OCM and R-OCM and all treatments at d 0 (Table 1). For folate intermediate concentrations, no plane of nutrition × supplement interactions (P ≥ 0.06) were found in fetal liver, ALF, or AMF; however, 5-methyl THF in ALF tended (P = 0.06) to be greater in R+OCM compared with all other treatments (Table 2). No interactions were found for concentrations in maternal liver when corrected for total liver weight; however, there was a supplement effect (P ≤ 0.05) where the concentrations of folic acid, dihydrofolate, tetrahydrofolate, 5-methyltetrahydrofolate, 5,10-methylenetetrahydrofolate and 5,10-methenyltetrahydrofolate were increased in +OCM compared with -OCM, and a plane of nutrition effect (P ≤ 0.05) with increased 5,10-methenyltetrahydrofolate and 5,10-methylenetetrahydrofolate concentrations in RES. We conclude that supplementing OCM increases concentrations of B12, folate and its intermediates in maternal liver and serum. USDA is an equal opportunity provider and employer.