Microbes In The Hindgut

I thought it would be a good idea to write a post on the microbes that live in the hindgut of the horse as this is the subject I am currently researching in for my dissertation. I am doing lab work during the days at the moment and also having to write other work up in the evenings which is why I haven't had the time to write blog posts.

In the horse's digestive system they have evolved to have a large hindgut (caecum and large intestine) as this is the main area in which their food is digested. Horses diets consist of a large proportion of forage which contain cellulose, this is difficult to digest. The microbes that live in the caecum are able to digest this cellulose. They live in the horses gut in a mutually beneficial relationship as they provide nutrients for the horse in return for a place to live. They produce volatile fatty acids for the horse.

These microbes include bacteria, protozoa and fungi and they all work in different ways. Most information that is known in this area focuses on the bacteria. The levels of bacteria present in the gut are very high, there can be between 500,000,000 to 5,000,000,000 bacteria per gram in the caecum. The levels present have been found to differ between horses. Native breeds often have higher populations present than other breeds, this may be due to them having to evolve to live in a more harsh environment and need to digest their food more efficiently. One of the main types of bacteria present is Streptococci, this is involved with the digestion of fibre.


The microbes in the hindgut are also thought to be involved with the onset of laminitis. The population present can be altered by a number of factors including the feed the horse is eating. Certain types of bacteria are more suited to digesting a high starch diet and other ones are better at digesting a high forage diet. This means that the population of bacteria will vary depending on what the horse is eating. This is also one of the reasons why you should make gradual changes to your horses diet and not change it abruptly. During a sudden rise in starch in the horses diet, lactobacilli bacteria will proliferate as they will be more suited to digesting this. This type of bacteria also produce lactic acid causing acidic conditions in the hindgut. This can lead to acidosis and also will kill off some of the other bacteria inhabiting the hindgut. 

For my dissertation I am looking at the effect worming horses has on the microbial population in the hindgut of the horse. There has not been any work looking in this area previously. After collecting poo samples from horses on they day they wormed, 2 days after and 2 weeks after (nice, I know) I have been analysing it in the labs. I have counted the levels of protozoa present under a microscope and now I am doing the DNA analysis to see which bacteria are present and in what levels.

I think this post is long enough now! Hope you enjoyed, I will write another post soon but they may not be coming as often as usual for the next few weeks.

Love Laura
xxxx