The Risk of Antibiotic Resistance

An increasing global demand for protein is driving a requirement for animal production, in combination with this there is an upward trend in the volume of antibiotics used worldwide. Statistical modelling maps indicate massive increases in human deaths attributed to antimicrobial resistance in the next 30 years ( Figure 1), consequentially antibiotic resistance is set to be the biggest cause of human deaths by 2050, with estimates as high as 10,000,000 per year (de Kraker et al., 2016).

Figure 1. Deaths attributable to antimicrobial resistance every year by 2050 (Source: BBC and Review on Antimicrobial Resistance – Tackling a Crisis for the Health and Wealth of Nations (2014))

There is increasing pressure from regulatory bodies to record and reduce the use of antibiotics in livestock production, especially those important to human health. However, reducing excessive antibiotic usage is also important for animal health. Failure or reduced efficacy of antibiotics will result in increased disease and poor livestock performance with significant economic impact. The reduction of antibiotic usage therefore is a one health issue, for both human and animal health alike. The solution to reducing or eliminating antibiotic dependency in poultry production requires programmes that are multifaceted in their approach combining biosecurity, management and nutrition. Eubiotics can be a valuable tool in these programmes.

The Role of Eubiotics?

Eubiosis is a term that refers to a healthy and diverse gut microbiota and has a profound impact on metabolic and immune homeostasis. Therefore the gut microbiota has a direct effect on animal health, wellbeing and consequently performance.  Whilst the poultry industry has been aware of the need to understand and manage gut health for a number of years, it is only recently, with the need to find alternatives to antibiotics, that the realisation of the true importance of the gut microbiota has come to the fore.

Eubiotics are dietary components which help to regulate the microbial population of the gut, by creating or restoring eubiosis. These can be broad in their composition, from botanicals and probiotic bacterial strains, through to short chain fatty acids (SCFA). While probiotics exert their effect largely via competitive exclusion, SCFA create an environment suitable for beneficial acidophilic bacteria (e.g. Lactobacillus) to proliferate, driving the development of gut microbiota. One such example, Salgard, provides SCFA such as propionic and formic acids presented on a mineral carrier which helps to ensure the product is active throughout the length of the digestive tract. Furthermore, the specialist carrier protects the product from reacting with in-feed nutrients and damaging levels of vitamins and minerals. These carriers allow acid dissociation within the animal without the need for enzyme digestion or the activity of emulsification which wax and fat coated acids rely on. This means that the eubiotic is highly effective in young and immune compromised animals, where fat digestibility can be impaired helping them to achieve a eubiotic status.

Development of the Microbiota – Achieving and Maintaining Eubiosis

The gastro intestinal tract (GIT) of the newly hatched chick is largely considered sterile, although there is some evidence to suggest that caeca of embryonic chicks can be colonised by bacteria from the mother hen. The state of eubiosis is most important in the chick as the initial colonisation of the gut with pioneering bacteria has profound lifetime effects. Development of the intestinal microbiota is generally considered to begin upon hatching, where bacteria are acquired from the environment. This is a crucial factor. The presence of pathogens or unwanted bacteria, for example E. coli, Salmonella or Enterococcus faecalis, in the environment can adversely impact the development of the gut microbiota, leading to poor lifetime performance and increased antimicrobial requirement and increased early mortality.

One day post-hatch the ileum and caeca are both dominated by bacteria with densities up to 1010 bacteria/g digesta. Within 14 days the typical adult small intestinal microbiota is well established and after 30 days the caecal flora has developed and ideally the intestine is in a eubiotic status. The diversity of bacterial populations of the intestinal microbiota increases with age, while nutritional influences are also apparent. Bacterial numbers in the mature microbiota range from 108 CFU/g, predominantly Lactobacillus spp. in the foregut to 1011 CFU/g in the hindgut, mostly Lactobacillus, Enterococcus, and various Clostridiacea. Estimates suggest as much as 50-85% of the remaining microbial identity in the gut are still unknown.

Eubiotics based on SCFA can be an effective measure to favour beneficial bacteria in the gut. Using antibiotics at this time if not always truly necessary, may be disruptive to proliferation of beneficial bacterial, delay gut maturation or lead to dysbiosis (Tompson et al., 2008). The gut is then at risk of further pathogen proliferation from antibiotic resistant strains and some opportunistic pathogens such as species of Salmonella (Pavia et al., 1990) and E. coli (looft et al., 2014). Eubiotics, conversely, work in a positive way to increase microflora diversity and stability, aiding the development of a mature, balanced gut flora and supporting animal growth. This enables the microflora to recover quicker should antibiotics need to be used, minimising the negative impact antibiotics can have on the microflora.

Promoting a Balanced Microbiota

Anpario’s acid based Eubiotics (ABE), such as Salgard, have a demonstrable beneficial effect upon the microbiota including the reduction of E. coli numbers and increasing levels of Lactobacillus with a detectable increase in levels of propionate and butyrate in situ. Lactobacillus spp. are known to help create a favourable microbial environment while propionate and butyrate serve as energy sources for cells of the intestinal villi as well as other beneficial  bacteria. Butyrate has also been shown to help increase gut health and barrier function as well as mucin production and is documented to reduce inflammation. This results in reduced energy costs and improved dietary utilisation, ultimately aiding bird performance but also helping to ensure they are more robust and can better deal with pathogen challenges. Figure 2 shows the effect Salgard can have on broiler performance, in this work a 69g benefit in body weight gain was seen in the growing period and a 1.8% reduction in lifetime mortality.

Figure 2. Salgard provided a benefit to broiler performance, with increased final bird weight (kg) at slaughter compared to birds fed control diets.

Using Eubiotics to Reduce Antibiotic Requirements

Improved utilisation of the gut microbiota and general bird health benefits can have the potential to improve lifetime animal health and help us to raise poultry with reduced reliance on antibiotics. In laying hens where health can be challenging to control, the use of ABE’s deliver the benefit of stabilizing the gut microbiota. This is important to reduce the impact of opportunistic pathogens such as C. perfringens or lower the risk of infection from zoonotic organisms such as Salmonella spp. and Campylobacter, a potential problem in both broilers and layers which can be transmitted from their feed, Salgard is able to control these pathogens (Figure 3).

Figure 3. Anpario ABE reduced the presence of Salmonella and Campylobacter in layer mash

Moving to a Eubiotic System

Eubiotics are important tools in the management of bird health where benefits can be seen in reduced need for disease intervention and benefits can be gained in bird health and efficiency. The development of a well-balanced and diverse gut microflora in the chick is crucial for later bird performance, whether they are broilers or layers. Which this the bird is more robust and able to deal with the normal pressures and challenges of commercial production. Eubiotics help maintain this beneficial state, minimizing the impact of enteric challenges through diet changes and pathogen challenge. Thus helping to reduce the reliance and usage of antibiotics in poultry production whilst maintaining strong bird performance.

Anpario plc is a UK based, world-leading, innovation driven animal health company producing Specialist Feed Additives that work in harmony with the natural aspects of both the animals’ biology and environment to promote healthy growth whilst providing a productive and sustainable future. For more information please see


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