| Factors associated with a failure to adapt metabolic and physiological regulation during the transition period include oxidative stress, metabolic disorders, and imbalanced energy status. Those factors are not only correlated to each other, but also related to low performance and immune suppression, which leads to development of periparturient-related diseases such as cytological endometritis (CE). The objectives of this work were to investigate the: 1) effect of source of trace minerals on production, oxidative metabolism, and the incidence of CE; 2) effect of chromium propionate (Cr-Pro) supplementation on production, metabolism, and the incidence of CE; 3) effect of supplemental monensin and varying postpartum fermentable starch level on the incidence of CE and related immune functions; and 4) association of CE with energy metabolism and inflammation. The first experiment found that, compared to inorganic or organic sources, supplemental hydroxy trace minerals (HTM), a recently available source of trace minerals, improved aspects of milk production, modulated plasma indices of oxidative balance, and reduced plasma haptoglobin levels immediately after parturition, suggesting that HTM are more bioavailable and can affect the body system related to production, oxidative metabolism, and inflammatory responses. In experiment two, feeding Cr-Pro resulted in improved prepartum dry matter intake in addition to reduced prepartum plasma non-esterified fatty acid (NEFA), and decreased incidence of CE along with increased uterine neutrophil influx immediately after parturition. This implies that Cr-Pro can improve periparturient energy metabolism and uterine immunity. The third experiment revealed that innate immune responses were improved during the early postpartum period in cows fed high starch diets for 3 weeks after parturition, and during early lactation in cows fed monensin. Finally, analyses conducted indicated that negative energy balance during the first 3 weeks after parturition was a critical factor to develop CE because cows with CE had higher area under the curve of plasma NEFA and beta-hydroxybutyric acid, and lower calculated energy balance during that period compared to cows without CE. The findings obtained from this work give practical approaches to optimize overall performance in transition dairy cows and provide partial mechanisms for how oxidative status, metabolism, and energy balance interrelate. |
