Sub-acute ruminal acidosis: a multidisciplinary approach to understand and prevent a multifactorial disease

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Sub-acute ruminal acidosis (SARA) affects some cattle herds, but not others, and individual animals within herds, but not others. The root cause of the dysfunction is the loss of control of ruminal and possibly intestinal pH. SARA is generally caused by grain feeding, but the basis of the variability requires better definition and the precise cause of inflammation and pathology remains uncertain. This project will monitor six beef and two dairy herds for nutrition and management and relate the information to post-mortem scores of ruminal wall lesions, liver abscesses and laminitis. The potential value of remote motion sensors in alerting farmers to problematic animals will be explored. Ruminal digesta and ruminal epithelial tissue samples taken post mortem will be analyzed by state-of-the-art microbiomic analysis based on 16S rRNA gene sequences, in order to identify significant differences in microbial communities in different animal types. Different Escherichia coli biotypes will be monitored. Bacteria will be isolated from least affected animals for their ability to inhibit the growth or adhesion properties of E. coli, on the basis that these animals may already possess bacteria that protect them from SARA. Candidate strains will be evaluated for their potential usefulness as probiotics to prevent or treat SARA. The hypothesis that soluble lipopolysaccharide (LPS) lies at the heart of the inflammation which results in pathology will be tested by measuring the quantities and nature of cell-free LPS in different animals. Possible feed additives that adsorb or break down LPS will be evaluated in digesta samples from badly affected animals. Demonstration animal trials will be carried out in the third year of the project to test the potential nutritional, management and feed-additive solutions identified by the project's results.

A wide international spectrum of academic researchers will benefit from the project, because SARA is a widespread problem internationally. Researchers interested in ruminant health and welfare and those whose main interest is ruminant gut microbiology will be the primary beneficiaries. They will be able to translate the results to their own production conditions where SARA is endemic. The results will be of wider interest, however, because although SARA is a disorder that afflicts ruminant species, researchers interested more generally in inflammation that originates in the gastrointestinal tract of other species, including man, will benefit. Related fields include equine health and poultry production: researchers in these areas will build upon the novelty of this project to determine if the aetiology of their target diseases, in terms of microbiology, inflammatory factors and pathology compare. New research and research proposals for these different animal species could result. Medical researchers may benefit too: the concept of soluble LPS has not yet been explored in human disease, for example. One might speculate that soluble LPS may have an important, as yet uninvestigated, role in inflammatory bowel disease (IBD) in man. Our project may spark useful medical research in this area. Microbiome profiling will provide information about how diet and the individual animal affect numbers and species of methanogenic archaea in the rumen, thereby aiding research into greenhouse gas emissions from animal agriculture. Ruminal microbial ecology in UK ruminants is under-studied in the modern era: the project will help correct that deficiency.
Veterinary practitioners and public sector advisers from colleges of agriculture and levy bodies will benefit by being better equipped to advise farmers. The project will describe management and nutritional factors associated with variations in the incidence of SARA, information that farmers' advisers can use on-farm. Vets will be able to make better diagnosis of SARA and they will be able to suggest solutions from those feed additives coming out of the SARA project. The probiotic(s) will be useful to help prevent pathological problems in susceptible farms and animals. The adsorbants may be useful in prevention but also to treat the condition. The market potential for a successful feed additive is many millions of pounds. The advisors may consider the remote monitoring system a useful mechanism to monitor the success or otherwise of strategies to ameliorate SARA. The academic partner expert in remote broadband technology has a spin-out SME that will benefit if the technology is found to be generally useful in an on-farm situation. The companies selling these additives and devices will benefit commercially. Initially, those will be from within the consortium. However, as the results are disseminated, more companies in the UK and worldwide will take up the technologies.
Farmers will benefit economically. The beef industry nationwide has a value of £2.22bn at 2009 values. It follows that even a 5% overall loss of productivity caused by SARA may cost livestock producers £111M p.a. Dairying has a similar incidence of therefore the loss to farmers (and the UK economy) could easily exceed £200M p.a. The economic impact will be felt across the globe in countries that suffer from SARA in their ruminants, including the US (26% of mid-lactation cows suffer SARA), the Netherlands and Germany (18%). Livestock production in the UK will gain against its international competitors and, by retaining the IP in the UK, the economic competitiveness of the United Kingdom will be enhanced. Societal benefit will stem from improved economics and sustainability of food production and a healthier national herd. The livestock will benefit by being less subject to the distress of SARA, thus enhancing animal welfare.