An evaluation of rumen-protected choline and monensin controlled-release capsule on milk production, health and metabolic function of periparturient dairy cows

This thesis presents an investigation of the effects of supplementing rumen-protected choline (RPC) and/or monensin controlled-release capsule (CRC) on blood metabolites, milk production and liver function in transition dairy cattle. Prior to calving, 185 Holstein cows were randomly assigned to receive one of the following: a CRC, RPC, CRC and RPC or neither supplement. CRC significantly increased serum concentrations of glucose and urea, while lowering concentrations of beta-hydroxybutyric acid and aspartate aminotransferase. Additionally, CRC administration increased liver glycogen content and decreased liver TG-to-glycogen ratios at 3 weeks into lactation. Conversely, RPC supplementation lowered serum cholesterol concentrations while significantly improving milk production in the first 60 days of lactation. There were no synergistic or additive effects in administering CRC and RPC on any of the outcomes measured. This study indicates the usefulness of CRC administration on improving energy metabolism and RPC supplementation on productivity in transition dairy cows.