During the periparturient period cows undergo immense physiological changes as they approach the end of gestation and the beginning of lactation. The prepartum cow in this stage has ceased lactating and has the primary role of supporting the growth of the fetus, which grows rapidly in the final weeks. The energy requirements of the cow during the dry period is low compared to other stages of lactation, and will increase slightly during the start of the periparturient period, and the diet consists mostly of forage and lower energy feedstuffs. When the cows has her calf, her nutrient requirements increase dramatically overnight. The onset of lactation is very energy demanding and requires the diet to change, mostly increasing energy concentrations using feedstuffs higher in starch. As cows transition onto those higher energy diets, the microbiome of the rumen will start to shift as well, microbes that utilize starch will start to proliferate that will change the dynamics of the rumen. These starch diets will lead to more ruminal production of volatile fatty acids as well as increasing concentrations of lactic acid, all acidic and results in a drop in rumen pH. Other microbes that ferment these acids and help balance the rumen pH tend to be slower to grow, and leaves the cow vulnerable to rapidly decreasing ruminal pH and could lead to acidosis. Acidosis can damage the microbiome and the rumen itself, as well as lead to systemic inflammation and negative health and production outcomes. The work in this dissertation was focused on strategies to mitigate those negative effects that can occur during the periparturient period. The strategies used were 1) supplementing cows with Saccharomyces cerevisaie fermentation product during the periparturient period to observe metabolism, inflammation, immunity, and performance, 2) to determine relationships of blood-based indices of liver health during the transition period with performance and health and 3) observe the effects of oral administration of Megasphaera elsdenii on production and health on commercial dairy farms. Our conclusions from those three sections showed that giving Saccharomyces cerevisaie fermentation product improved cow performance in the early postpartum period; however, there was evidence of increased acute phase proteins postpartum as well. It was also observed that indices that score liver health were successfully able to categorize cows, showing that higher liver scores were associated with positive productive and health outcomes. Administering Megasphaera elsdenii led to less cows being involuntarily culled, as well as an increase in rumination for primiparous cows and less rumination for multiparous cows. Primiparous cows also had less rumination variability, possibly meaning a more stable rumen environment.