Folic acid supplementation regulates milk production variables, metabolic associated genes and pathways in perinatal Holsteins.

Perinatal period is the critical time in dairy cattle due to negative energy balance and high milk production stress. Being a key role in biosynthesis and methylation cycle, folic acid is considered essential for lactational and metabolic performance in dairy cattle. Thus, the current study was designed to evaluate the effect of folic acid supplementation on milk production phenotypic traits in periparturient cows. Transcriptomic screening was performed for milk production and metabolism-associated differentially expressed genes. The 123 cows having similar parity, weight and expected date of calving were randomly selected and divided into three groups; A (n = 41, folic acid 240 mg/500 kg cow/day), B (n = 40, FA 120 mg/500 kg cow/day) and C (Control, n = 42). Folic acid was supplemented for 21 days (14 days pre- and seven days post-calving), and three samples of blood lymphocytes were taken on day seven post-calving from each folic acid-treated and control group. In addition, the milk samples for each folic acid-treated group have been collected at 2nd, 3rd and 4th month of lactation. The increase in average milk yield noticed in group B were significantly (p-value < .05) higher than C and A. However, the data showed no noteworthy differences for milk fat and milk protein among the three groups. The transcriptomic analysis revealed that folic acid treatment regulated many key metabolic-related genes (DGAT2, ALOX5, LAP3, GPAT3, GGH, ALDOA, TKT) and pathways (glycolysis, folate biosynthesis, glutathione metabolism, etc.) in periparturient dairy cattle. It was concluded from the above findings that 120 mg/500 kg of folic acid quantity could be considered as a standard during the periparturient period to enhance the milk production performance of dairy cows. The transcriptomic profile revealed several metabolic and milk production-associated genes which could be a useful addition to the marker selection for the enhancement of metabolism and milk production of periparturient dairy cows.