Epidemiological assessment of hyperketonemia in dairy herds: implications for disease diagnosis and control

Abstract

Metabolic disorders are a frequent problem in the transition period of dairy cows. During this period, higher concentrations of circulating ketone bodies, known as hyperketonemia (HYK), indicate that the cow is utilizing body reserves to fulfill the energy requirement of her new physiological state. Hyperketonemia has been associated with other metabolic and infectious diseases during early lactation, decreased milk production, increased likelihood of herd removal, and impaired reproductive performance. However, the influence of the energy balance during the late dry period on the development of HYK has not been fully quantified. Similarly, the role that milk yield in early lactation plays in hyperketonemic cows due to the importance that the lactogenesis process has in the energy balance needs to be explored. In terms of diagnostics, it has been reported a differential effect of HYK in multiple health outcomes and production according to the moment of disease diagnosis. However, these effects have been evaluated only in the short term. Understanding the effect of HYK in the entire lactation according to the moment of disease diagnosis is needed to determine the optimum timeframe for diagnosis. Consequently, the goal of this dissertation is to better understand the epidemiology of HYK to guide the implementation of optimal decisions to control and diagnose the occurrence of the disease. Our results suggest that a) cows with loss of BCS over 0.5 points during the late dry period have the peak of BHB concentration at day 7 of lactation and have a higher risk of HYK than cows without variations in BCS during the late dry period. b) The impact of HYK on health and productivity varied according to the moment of diagnosis. HYK diagnosed on the first week of lactation was associated with lower milk production and pregnancy rate, and with a higher risk of early removal from the herd than non-hyperketonemic cows. c) Furthermore, it was observed that early milk yield plays a role in the association of HYK with reproductive performance. Among low producers, hyperketonemic cows were less likely to become pregnant. Conversely, reproductive performance was similar among mid- and high-yielding cows, independent of HYK status. In conclusion, to prevent HYK in early lactation, management strategies in the prepartum period should focus on preventing loss of BCS over 0.5 points. After calving, the diagnosis of HYK should be performed at the first week of lactation, and especially targeting cows with lower milk yield. Although more studies need to be performed to improve HYK control, this dissertation provides tools to prevent and control the disease in dairies, with straightforward farm-applicable strategies.