Ask Equine Expert - My vet

"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

Ask Equine Expert - I've been told

"I’ve been told that supplementing selenium can be a good thing but I’ve also read that horses have died from selenium toxicity. What is selenium used for in the horse and can I supplement it safely?"

Selenium (Se) is a component of around 25 proteins, including glutathione peroxidise. These selenoproteins have major roles in metabolism and rely on the availability of Se in the body and/or diet. Selenium also plays a role in the immune system, gene expression, thyroid metabolism and male fertility. Therefore, adequate Se status in the horse is vital for optimum health and performance. Many areas of Europe have soils that are classed as Se-deficient (especially Scandinavia) and it is common place to fortify feed with inorganic Se, usually as sodium selenite (NaSe). However, inorganic Se, as well as other minerals is poorly absorbed by the digestive tract and not readily stored in the body, resulting in very low, if any, Se reserves. In contrast, Se absorbed from organic sources, such as selenium yeast, can be incorporated into either selenoenzymes or general proteins in the body as storage for future use. This enables the animal to build Se reserves for times of stress, such as foaling, illness and high intensity exercise. Exercise may be of particular importance with regards to Exertional Rhabdomyolysis (Tying-up, Azoturia).

Many studies have shown greater incorporation of Se from an organic source into body tissues compared with NaSe. This is because organic Se is the form that the mammalian body has evolved to use. The body recognises this form and it is absorbed and incorporated into the body much more effectively. With regards to the issue of toxicity, NaSe is actually toxic to mammals over certain levels and, as such, European law states maximum supplementation of 0.5mg/kg in complete feeds. The toxicity of NaSe is in contrast to organic selenium as selenium yeast, for example no toxic level (as measured by LD50) has been found for Sel-Plex® (Alltech Inc., Nicholasville, KY). Horses are very sensitive to Se levels and develop signs of toxicity more quickly than other animals, such as cows, for example, therefore, organic selenium seems to offer a safer way of supplementing optimum levels of selenium.

Expert Answer by: Helen Warren