A horse’s hindgut contains billions of microbes, known collectively as the microbiome that breakdown the fibre they eat, through a process called fermentation, converting it into a usable energy source. These include bacteria, that are predominately responsible for fibre fermentation, but also Protozoa, Archaea, and fungi, that all live in a delicately balanced hindgut ‘community’ within an optimal pH of 6.5-7.
The health and stability of the microbiome is positively linked to the health of the horse, so it’s essential to ensure it stays healthy and well-balanced with the right nutrition. Probiotics and prebiotics are nutritional additives that help nurture, stabilise and stimulate beneficial microbes in the hindgut. You will find them widely used in horse feeds and supplements to help promote digestive health – but is there any evidence that they work?
Lisa Elliott, MSc – Equine Nutrition Solutions, explains what pro and prebiotics are, how they work, and the current scientific evidence for their use to promote optimum hindgut and digestive health.
Probiotics
Probiotics – also know as ‘direct-fed microbials’ have been widely used in horses for treatment and prevention of gastrointestinal disease. The Food and Agricultural Organisation of the United Nations define probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host”
Probiotics include specific strains of bacteria and Yeasts. Yeast (which are microscopic fungi) in the form of yeast cultures, can be introduced to a horses digestive tract through the feed, and once in the hindgut are thought to stimulate beneficial, fibre-digesting bacteria to increase fibre digestibility and maximise the health of the hindgut. One strain of yeast, known as Yeasacc (Saccharomyces cerevisiae 1026) is included within the core formulation of Coligone to support digestive health.
Yeasacc
Yeasacc has been widely researched within equine digestive health and produced a range of results. A notable number of research studies both in vivo (inside the body) and in vitro (outside the body, using faeces) have indicated an increase in fibrolytic activity within the hindgut microbiome (Glade et al. 1991, Medina et al. 2002, Morgan et al. 2007, Jouany et al. 2008, Santos et al. 2006, Warren and Hale 2016), in studies where horses were fed Yeasacc. Increased fibrolytic activity means better fibre digestion and improved nutrient availability for health and performance. Additional studies (Perrone et al. 2013, Glade and Campbell-Taylor, 1990, Glade, 1991) have supported this improved nutrient availability by showing higher nutrient digestion and improved growth and performance in horses fed Yeasacc.
Yeasacc has also been found to have positive effects in horses fed a high starch diet (Medina e al. 2002; Jouany et al. 2009). High levels of dietary starch are associated with a drop in hindgut pH which can lead to acidosis and microbial dysbiosis. However, Yeasacc was shown to increase hindgut pH when fed alongside a high starch diet (Medina et al. 2002) improving the environment for beneficial fibre-digesting bacteria to thrive. Furthermore, a Yeasacc based supplement was associated with a rise in lactic-acid producing and lactic acid utilising bacteria (Jouany et al, 2009). Although an increase in lactic acid producing bacteria has been associated with acidosis (Al Jassim and Andrews, 2009), a small increase in number can be beneficial as lactic acid can be converted into a valuable energy source, which were promoted by the Yeasacc, thereby decreasing the chance of lactic acid accumulation, and resulting acidosis.
These studies have shown that Yeasacc supplementation significantly improves the digestibility of fibre but also goes some way to mitigating the negative effects of diets containing high levels of starch. Also, helping to support a healthy, balanced microbiome and improved overall health and wellbeing.
Prebiotics
Prebiotics are defined as “a substrate that is selectively utilized by host microorganisms conferring a health benefit”. Prebiotics most used in animal nutrition include oligofructose, inulin, fructooligosaccharides (FOS), and mannanoligosaccharides (MOS). FOS and MOS are included as core ingredients throughout the Coligone range.
MOS (mannanoligosaccharides) work by binding pathogenic microbes within the digestive tract and removing them from the gut, reducing their ability to attach to the gut wall and initiate disease. This helps to promote beneficial bacteria and keep the microbe population stable and balanced, along with supporting optimum immunity within the hindgut.
Research with MOS supplementation in horses has reported that the incidence of diarrhoea was significantly reduced in the foals of mares supplemented with MOS prior to and following foaling (0tt, 2005). Pregnant mares supplemented with MOS were also shown to have increased levels of immunoglobin (IgG), which is a recognised antibody in their blood and produced colostrum with higher levels of antibodies (IgG, IgM, IgF) which were then passed to foals via colostrum, ensuring better resistance to pathogens within the environment (Spearman et al. 2004).
Research in other animals has investigated the ability of MOS to support overall health, well-being and performance and has provided positive results. Studies involving dogs, rabbits, pigs and cattle have shown MOS to reduce E.Coli a known pathogen whilst promoting greater concentrations of beneficial bacteria (Jacques et al. 1994, Morrison et al. 2010, Strickling et al., 2000; Swanson et al., 2002a; Grieshop et al., 2004; Gouveia et al., 2006). Additionally, MOS has been shown to mitigate digestive upset during weaning and transition to compound feeds and support gut health and improved performance, including weight gain and feed conversion (Heinrichs et al., 2003; Miguel et al., 2004; Mourao et al. 2006; Rosen, 2006; Ghosh and Mehla, 2011). The ability of MOS to support hindgut microbes, improve hindgut health and boost immunity is supported by a wide body of research which helps prove its efficacy to promote digestive health.
FOS (fructooligosaccharides) supports digestive health by providing a feed substrate that beneficial hindgut microbes can use to flourish and grow. FOS has been quite widely investigated for its ability to promote beneficial microbes and mitigate digestive and microbial disturbances.
Research studies with horses supplemented with scFOS (short chain FOS) have suggested that scFOS may help to limit the detrimental effects of a sudden change to a higher starch diet (Respondek et al. 2008). In horses fed scFOS and subjected to a sudden change to a high starch diet, numbers of lactic acid producing bacteria did not increase, pH was stabilised and lactic acid was not able to accumulate within the hindgut.
Similarly, another study (Berg et al. 2005) where scFOS was fed to yearlings, showed increased faecal pH and also an increase in the Volatile Fatty Acids (VFA) acetate, propionate and butyrate. This is significant because this demonstrates improved digestion but also butyrate helps to promote gut wall health and integrity. This study also reported a decrease in pathogenic E.Coli with the addition of scFOS, due to bacteria that were able to use scFOS being able to competitively exclude E.Coli from the hindgut. Additionally, scFOS has also been shown to mitigate decreases in digestibility encountered by senior horses (Heaton et al. 2019).
These research studies demonstrate that scFOS may beneficially influence the hindgut microbiome, digestion, and hindgut integrity, justifying its efficacy as a valuable addition to support optimum digestive health.
Combining the proven effects of Yeasacc, MOS and scFOS throughout the Coligone range, means they all work together to promote a healthy, stable microbe community and maximise digestive health in all horses and ponies, whatever their stage of life and work level.
