Nutritional Implications For Oxidative Status Immune Function And Energy Metabolism In Transition Dairy Cows And Relationships With Postpartum Performance And Endometritis
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Nutritional Implications for Oxidative Status, Immune Function, and Energy Metabolism in Transition Dairy Cows and Relationships with Postpartum Performance and Endometritis
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.
Adiposity, Energy Metabolism, and Immune Function in Dairy Cows
This thesis aims to focus on defining how adiposity interferes with energy metabolism and how this condition could lead to immune system dysregulation. The central hypothesis is that the demand by the mammary gland for nutrients to synthesize milk, specifically calcium and energy, results in a homeorhetic shift in the dam to support lactation, resulting in an increased incidence of hypocalcemia and dramatic changes in body condition (BCS), leading to depressed immune function. The first study demonstrated that energy manipulation of the diet during late lactation promoted differences in body reserves. However, it suggested that cows have a biological drive to attain a target BCS, as cows changed their body reserves during the dry period. The second study highlights the substantial individual variation in the magnitude of response to the dietary treatments, demonstrating that fat mobilization and energy balance patterns vary among cows within the same dietary regimen, and insulin is positively correlated with body reserve deposition. The third study's findings indicate that differences in BCS at parturition can influence feed intake without significantly affecting immune function and calcemia during the periparturient period. The fourth study extends the previous studies and describes the several effects of high, medium, and low BCS at calving. Our findings indicate that a high BCS 7 days prepartum is associated with lower dry matter intake, reduced milk production postpartum, and a more pronounced negative energy balance, suggesting that maintaining a high BCS during the dry period negatively impacts milk yield in the subsequent lactation. In the fifth study, we demonstrated that manipulating circulating calcium levels during the first 24 hours postpartum did not affect immune function significantly, as assessed by changes in haptoglobin, cytokine concentrations, and neutrophil activity. Together, this thesis underscores the complex interplay between adiposity, energy metabolism, and immune function in dairy cows during the peripartal period. It highlights the biological drive to regulate body condition, the detrimental effects of high BCS on postpartum performance, and the limited impact of acute calcium manipulation on immune parameters, providing valuable insights for improving dairy cow health and productivity.
Relationships Between Carbohydrate Nutrition and Metabolism, Inflammation, and Performance of Dairy Cattle During the Periparturient Period
The transition from pregnancy to lactation is a time of great metabolic adaptations for the dairy cow. Dry matter intake decreases, yet demand for nutrients increase vastly with the onset of milk production resulting in negative energy balance. Cows must mobilize body tissues to increase energy for the body while sparing glucose for the mammary gland. Due to this increased metabolic demand and negative energy balance, cows often end up in a state of metabolic dysfunction which can have disastrous consequences. Nutritional strategies can help increase glucose precursors while decreasing body tissue mobilization that is linked to increased risk of disease. Previous research is mixed on the impacts of high starch to increase glucose precursors to the cow immediately postpartum, likely due to an increased risk for subacute ruminal acidosis that can result in metabolic dysfunction and inflammation. Feeding strategies which utilize high starch while also including higher fiber to promote rumen health have not been conducted. The objectives of this dissertation were to: 1) investigate interplay of fiber fractions in high starch postpartum dairy cow diets on performance, hepatic metabolism and energy balance, 2) examine interplay of inflammation, hepatic metabolism, energy metabolites, and metabolic hormones in the postpartum period, and 3) investigate opportunities to combine use of a higher digestibility corn silage with monensin to optimize production and health in the periparturient period. Increased fiber in the postpartum diet can limit intake in early lactation, resulting in negatively altered metabolism and production. As intake restrictions were eased by feeding a more fermentable diet, cows were able to recover intake, production, and energy metabolites in a matter of days to match cows that were not limited in intake early postpartum. Increased fiber in diets that may pose a higher risk of subacute ruminal acidosis may still be warranted, though further research on fiber levels and fractions is needed. Correlations between improved hepatic metabolism and metabolic hormones indicative of energy balance were positive, though correlations between markers of improved hepatic metabolism and inflammation were negative. Cows fed corn silage with higher digestibility and monensin, which increases glucose precursors, showed a possible synergistic effect on milk production. Using either strategy alone increased energy status, improved metabolism and health status, however a combination of both strategies decreased milk components, indicating they might negatively alter the rumen environment and milk fat synthesis.