The dairy industry is under constant pressure for maximal productivity and efficient utilization of resources. Our ultimate goal is to improve lactational performance by modulating homeorhesis and promoting metabolic health during the transition period. We have developed a recombinant interleukin 8 (rIL-8) to mitigate the incidence of uterine diseases. Besides improving uterine health, a single intrauterine infusion with rIL-8 increased milk production by 3.6 kg/day. We have replicated the results of this initial clinical trial on a second study that used 3 different doses of intrauterine rIL-8. Additionally, we have demonstrated that a single intravenous administration of rIL-8 increased milk production by 4.5kg/day. Lastly, to investigate the potential mechanism of action, we have proved that systemic administration of rIL-8 in Holstein calves induced strong and long lasting insulin resistance. Preliminary results support a systemic effect of rIL-8 on metabolic health, which likely involves control of liver function, response to insulin, and appetite.