Comparison of the metabolic and redox status between organically and conventionally managed periparturient dairy cattle

Resumo

Yearly, millions of dairy cows succumb to transition cow diseases. An appropriate transition from late pregnancy to early lactation is vital for animals¿ health and productivity. It has been also stablished that oxidative stress (OS) is the nexus between nutrition, metabolism and inflammation; potentially increasing the susceptibility of dairy cattle to diseases. On the other hand, the number of organically managed dairy cattle (OMC) has increased 15-fold in the last decade within the European Union in. However, little information is available about the adaptation processes to the onset of lactation in OMC, and no previous study investigated the redox status of these animals. Therefore, the aim of this PhD thesis was to perform a preliminary assessment of the metabolic and redox status of OMC around the time of calving, comparing it with animals managed conventionally (CMC). Our results have shown that the Oxidative Stress index provides an objective assessment of the balance between pro- and antioxidants in periparturient dairy cattle, bringing one step forward the on farm application of redox status assessments. OMC, despite lower metabolic demands, might be at the same risk of suffering OS than CMC due to a lack of extra-antioxidant supply. The prevalence of subclinical ketosis was higher in OMC, although they showed better insulin sensitivity, a lower degree of inflammation and less liver injury, without a higher risk of macromineral deficiencies. Besides, our results stablished an association between oxidative status and insulin resistance in periparturient dairy cattle, which should be investigated further.