Ruminal fluids as substrate for investigating production diseases of small and large ruminant species

Production diseases are a huge problem for high-yielding dairy cows, especially during the post-calving period when a negative energy balance is present and the animals are unable to achieve enough feed energy intake to match their high requests. Correct management of production diseases demands an early diagnostic approach and prognostic parameters. In ruminants, metabolic stress greatly influences forestomach physiology, including immune responses. Therefore a proper evaluation of production diseases in ruminants should also include markers of the innate immune response to metabolic stress. New studies suggest that forestomach immune responses could be focused to ‘dangers’ arising in the rumen (diet unbalance, abnormal fermentations), but also arise as reporter system of disease conditions elsewhere in the body. This means that ruminal fluids could be useful diagnostic specimens, and their immune markers could integrate consolidated diagnostic parameters (e.g. rumen pH and volatile fatty acids, milk cell counts, blood, faecal analytes) and contribute to robust, early diagnosis of production diseases in dairy cattle.