Methylenetetrahydrofolate reductase gene polymorphism and the effect of transition period choline and methionine supplementation on some metabolic parameters and milk yield characteristics in cows

This study investigated the effects of methylenetetrahydrofolate reductase gene (rs110692574) polymorphism, as well as the effects of different ratios of choline and methionine supplementation, on biochemical parameters, milk production, reproductive characteristics, and health problems in Holstein cattle raised in Türkiye during the transition period. The study's animal subjects were Holstein cows raised on private farms in the Balıkesir province. In the initial phase of the present study, the genotypes of the subjects were ascertained with respect to the methylenetetrahydrofolate reductase gene rs110692574 polymorphism. The genotyping process was executed through the implementation of the Tetra-primer ARMS-PCR method. Individuals who carried the T allele at a lower frequency (CT genotype) were prioritized, and a research group consisting of 80 heads was formed. The animals in the research group were classified according to genotype (CC and CT) and feed additive treatments (CH: choline and CH+MET: choline + methionine) and divided into four groups. In the present study, a comprehensive analysis was conducted on the levels of homocysteine, folic acid, vitamin B12, and NEFA in blood samples extracted from animals on the 21st day prior to parturition, the day of parturition, and the 21st day thereafter. Post-calving BHBA levels and records pertaining to birth, lactation, milk yield, and health were obtained from the digital herd management system. The temporal effects of genotype and feed additive groups on biochemical parameters were analyzed using repeated measures analysis of variance, and the effects at different times were analyzed using the general linear model. The frequency of animals carrying the T allele in the Holstein cattle population in Turkey was determined to be 12.64% as a result of the analysis. The interaction between time and genotype exhibited a statistically significant effect on the alterations in folic acid and vitamin B12 levels across the various stages of the transition period (p < 0.05). A comparison of CC and CT genotype groups revealed substantial disparities in folic acid and vitamin B12 levels during the pre-calving period (day -21) and in BHBA levels on day 7 post-calving. In a similar vein, statistically significant disparities were identified between the CH and CH+MET groups with respect to folic acid levels on calving day (day 0) and post-calving day 21. Furthermore, it was elucidated that feed supplementation exerts a substantial influence on 100-, 200-, and 305-day milk yield. The rs110692574 polymorphism has been demonstrated to be associated with certain health concerns that could potentially result in yield reduction. These findings underscore the necessity of formulating customized nutritional strategies predicated on genotype, with the objective of preserving metabolic balance and enhancing yield characteristics during the transition period.