"I keep reading that yeast supplements may be good for fibre digestion. Is there any truth behind this?"

There is a lot of literature on this topic for a few species of animal. The use of yeast in diets for horses has been popular for a number of decades but, while there are general benefits to the use of yeast, it is important to consider that not all yeasts are the same – absolute effects and efficacy will vary with product. The majority of yeasts will be Saccharomyces cerevisae, however, there are many different strains within this species. Differences between strains can result in differences in how effective products are. The majority of yeast supplements aim help fibre-degrading bacteria breakdown forage resulting in more energy for the horse from the same amount of forage. They also help to keep the hindgut environment free from oxygen by mopping some of it up. The thing to remember is that not all yeasts are the same – some strains have been cultured specifically for their effect on fibre degradation. Therefore, it is best to choose a yeast supplement that has a proven mode of action and sound, supporting scientific data behind it.

Expert Answer by: Helen Warren

"My vet has advised that I get my hay analysed. What should I be analysing it for?"

There are many things for which you can get your hay analysed. It really depends on why your vet has advised you to have this done. The most usual reason is to have it analysed for its nutritional content. This means that you can have a much better idea of the contribution your hay is making to your horses daily nutritional requirements. It also means you can use it to work out how much hay you should be feeding, based on your horses daily nutrient requirements.

This type of analysis will give you an idea of the moisture level, energy, protein, fat and carbohydrates in your hay. The carbohydrate portion can be further broken down into fibre, as well as starch and sugars. The protein fraction can also be broken down into the essential amino acids, such as lysine, to give an idea of the quality of the protein in the forage. Vitamins and minerals can also be included in more detailed analyses. This information, together with your horse’s body weight and workload, can be used to balance his daily ration. Methods used to determine nutrient content are usually wet chemistry (labour intensive but an absolute measure of the nutrient you are investigating) and NIRS (Near Infrared Reflectance Spectroscopy – rapid with many samples analysed at a time but can be less accurate than wet chemistry).

Other types of analyses include screening for mycotoxin contamination. This is often more expensive than nutrient analysis and there are many different techniques used to carry it out. The more advanced the technique, the more accurate and detailed the results. It is always worth finding out what methodology laboratories use in order to be able to interpret the results correctly. A good lab will always help with this interpretation. Remember that any forage will vary from bale to bale, batch to batch, so your analysis for one sample may not represent an analysis for another. It is often useful to look at average results for the season – many labs can help with this information.

Expert Answer by: Helen Warren

"This year has seen a rise in the number of reported issues involving mycotoxins from pasture. What exactly are mycotoxins and why are they such a problem?"

Mycotoxins are produced by fungi (moulds) and are what’s known as secondary metabolites. The fungi produce these toxins when they become stressed by various factors e.g. drought, flood, hail, extremes of temperature, planting date and harvesting techniques. They are very stable compounds that are resistant to things like heat, acid and alkali, so they are virtually impossible to destroy by conventional processing methods. There are hundreds of different known mycotoxins that have varying levels of toxicity in different species of animal. One mould may produce many different mycotoxins and the same mycotoxin may be produced by different moulds. They are found everywhere, most commonly in grain and forage but also can be found on straw and shavings. Probably the most well-known are deoxynivalenol (DON) and zearalenone (ZEA) both produced by Fusarium moulds.

Most mycotoxins impair the immune system but others can be carcinogenic, mutagenic and teratogenic. In horses, Fescue Toxicosis (Neotyphodium coenophalium) and Ryegrass Staggers (Neotyphodium lolii) are the more severe problems associated with pasture mycotoxins. Contamination with fumonisin (a Fusarium mycotoxin) can lead to Equine Leucoencephalomalacia, a rapidly fatal condition. This is rare and chronic, low level exposure is more common. There are many ways to minimise the risk of mycotoxicosis, including testing pasture for the presence of mycotoxins. This is relatively expensive and requires sound interpretation of the results. A more cost effective approach would be to include a proven mycotoxin binder if contamination was suspected.

Expert Answer by: Helen Warren

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