Often during Spring horses are locked up for extended periods to keep them off the rich grass and the danger of Laminitis at bay.
This means that they will be fed larger portions of hay that could be coming up to 8-10 months old, or even two seasons old if last season’s hay is getting scarce.
Compared to fresh grass, the nutrient profile of hay can be quite different. This is because some vitamins and fats are fragile and are lost in the curing process or can decline over time.
Some of the main nutrients to consider include:
Fresh hay is rich is Beta-Carotene, a precursor of Vitamin A, however these decline as the hay ages. Once hay loses its fresh green colour you can assume that the levels of Beta-Carotene and therefore Vitamin A, have dropped considerably.
Vitamin A is an essential nutrient and important for vision, immune function, fertility and foetal development, bone and red blood cell production, skin, hoof and eye tissues, it’s also an antioxidant.
Depending on the age of hay it could be wise to supplement between 15,000-25,000IU/day.
The other vitamin that declines with older hay is Vitamin E, probably one of the most important antioxidants and stress fighting vitamins.
Any horse on a hay only diet should be supplemented with Vitamin E at a rate of between 2000-5000IU/day.
Vitamin C is important for a healthy functioning immune system, for skin and coat, respiratory, ligament and tendon health. It can decline quickly when forage is cured.
Horses on hay only diets can benefit from an extra 1-5g/day.
Omega 3 fatty acids also tend to decline quickly in the curing process, so some supplementation is wise. A good place to start here is 120-170g/day, ideally freshly ground, or ground and frozen, the fats are fragile and can decline quickly once the seed is broken. See the article on Linseeds for more info.
Horses on Hay diets may also require extra help to remain hydrated. Pasture is usually over 70% water whereas hay can be as low as 10%! Making sure the horse is adequately hydrated is extremely important for gut health and function and can guard against colic and other digestive issues.
Supplementing with salt (sodium chloride) at levels of around 1-2 tbsn/day will increase blood concentration of sodium and in turn will trigger the horse to drink more.
Other gut supporting supplements could include a good probiotic which will improve digestion along with a prebiotic like psyllium husks. Psyllium can be very useful when fed wet to carry water to the hindgut, and help to feed the microorganisms, as its very high in fibre.
Feed around 50g/day of psyllium for use as a prebiotic.
The mineral concentration can decline in older hay so feeding a daily Mineral supplement that is designed to balance out the mineral ratios and counteract high levels of Iron will be beneficial. Look for high levels of Zinc and Copper, some Iodine and Selenium and NO added Iron and Manganese.
Iron and Manganese is already very high in Equine Diets and can interfere with the absorption of the already deficient minerals like Zinc and Copper that are so crucial for health.
It may be beneficial to ensure the hay is being fed off the ground. Horses eating hay from the ground, especially on bare soil could be at risk of eating sand and dirt which can go onto cause sand colic.
Consider feeding hay in several hay nets tied to trees or safely to gates or fences.
If feeding off the ground is unavoidable then make sure to include a monthly psyllium husk purge by feeding 100-250g/day for 5 consecutive days.