ISSUE FOCUS FEED & ADDITIVE MAGAZINE October 2023 47 The sampling of fresh faeces and fresh poultry cecal content and cecal droppings has been made practically transposable in commercial barns as BioFreeze vials prevent any reaction from occurring in the sampled material, and without the need for the material to be kept in a freezer or on dry ice until it is analysed. We have now defined standard sampling protocols in commercial settings, making it possible to determine the optimal number of samples to be collected to ensure the measurements are representative of the herd and that the power of detection is strong enough to support data analysis. EVALUATING MICROBIOME FUNCTION In poultry, the ceca is the major site of bacterial fermentation. Short chain fatty acids (SCFA) are metabolites produced by fibre-degrading bacteria. In addition to providing an energy source to the epithelial cells, SCFA play other roles –such as intestinal acidification, which prevents pathogen invasion and colonisation. Each of these metabolites has a functional role for the host, and understanding their metabolism can contribute towards understanding the animal response better. The SCFA in the ceca of healthy birds are expected to exceed 100 mmol/kg passed 2 weeks of age. While acetate typically makes 70% of the SCFA, propionate and butyrate represent approximately 25% of the SCFA, and the remainder is composed of short-chain fatty acids, valerate and lactate. Lactate is a SCFA highly present in the upper gut. However, lactate accumulation in the ceca may provide a good indicator of dysbiosis. Our database has shown lactate levels to be below 1 mmol/kg in healthy birds, when it can reach more than 30 mmol/kg in birds subjected to dysbiosis. Butyrate is a metabolite of butyrate-producing bacteria, mainly represented by Clostridiales. Butyrate is an important metabolite that stimulates gut integrity by providing an energy source directly available to the epithelial cells. In commercial settings, we have measured that butyrate concentration in the ceca mainly correlated with Ruminococcaceae and Lachnospiraceae presence, which negatively correlated with lactate level (AB Vista, internal data). Branched chain fatty acids (BCFA) are a specific group of SCFA, mainly composed of 2-methylbutyric acid, isobutyric acid and isovaleric acid. BCFA are not desired in the ceca as they are a sign of protein fermentation, associated with an excess of dietary protein or poor protein digestibility. Protein fermentation eventually leads to putrefaction and opportunistic pathogen overgrowth. Our measurements determined that BCFA concentration in the cecal content of healthy broilers and layers tends to remain at low levels, typically below 3 mmol/kg. CONCLUSION With gut health a major area of focus for the animal production industry, there are a lot of practical questions still to be answered to provide producers with an optimal tool for monitoring and evaluating gut integrity. AB Vista’s objective – through our ongoing work in this area – is to provide producers with gut health indicators that supplement traditional performance data for a better understanding of animal responses to different nutritional strategies. About Virginie Blanvillain Rivera Born and raised in France, Virginie Blanvillain Rivera lives in Quebec, Canada. She developed an international experience in the animal feed industry by working in research and development, technology transfer, nutrition and quality assurance. Over the past years, she has been actively involved in the development and implementation of innovative tools and services for nutritionists, producers, integrators and feed mills. She provides training and technical support to the AB Vista network worldwide, while leading the development and continuous improvement of NIR, carbon emissions and lab services.
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