PSIV-8 The impact of nutritional planes and one-carbon metabolite supplementation during early pregnancy on phosphorylated p38 MAPK abundance in the bovine maternal liver.

Abstract The objective of this study was to investigate the effects of nutritional planes and one-carbon metabolite (OCM) supplementation during early pregnancy on the abundance of phosphorylated p38 mitogen-activated protein kinase (p-p38 MAPK) in the maternal liver at day 260 of gestation. A 2 x 2 factorial design was used with two nutritional planes; control (CON; 0.45 kg/d) and restricted (RES; -0.23 kg/d), with or without OCM supplementation (+/- OCM). Crossbred Angus beef heifers were synchronized for estrus and bred via artificial insemination using single-sire female-sexed semen. At breeding, heifers were randomly assigned to one of four dietary treatments (n = 8 ± 1 per group). Nutritional treatments were administered from day 0 to day 63 of gestation, after which all heifers were provided a common diet (0.45 kg/d gain). OCM-supplemented groups received daily rumen-protected methionine (7.4 g/d), choline (44.4 g/d) in a corn carrier, and weekly injections of folate (320 mg) and vitamin B12 (20 mg), while non-supplemented groups received only the corn carrier and saline injections. Maternal liver samples were collected at day 260 of gestation and analyzed via anti-phosphorylated p38 MAPK immunofluorescence, with image analysis performed using ImagePro-Premiere software. There was no nutritional plane x OCM interaction (P = 0.28), and p-p38 MAPK abundance did not differ (P = 0.13) between nutritional planes. However, heifers receiving OCM supplementation had a 54.75% higher (P = 0.02) p-p38 MAPK density per cell compared to non-supplemented heifers. These findings suggest that OCM may play a critical role in modulating cellular signaling pathways, particularly p38 MAPK, which is involved in stress responses, inflammation, metabolic regulation, cellular proliferation and differentiation. The increased activation of p38 MAPK in OCM-supplemented heifers may reflect improved hepatic function or adaptive responses to the physiological demands of pregnancy, potentially supporting maternal metabolic adaptation and fetal development. Further research is warranted to explore the downstream effects of enhanced p38 MAPK signaling and its broader impact on pregnancy outcomes. USDA is an equal opportunity provider and employer.