Even a cool mix sends my Arab mare crazy. I want to do some endurance rides but don't know what to feed. I have heard that vegetable oil is good.
It sounds as if your mare is 'grain sensitive'. Try Evenkeel, which is free from whole oats, barley and maize. 1kg/day will provide all the minerals, trace elements, amino acids, etc, she needs for a healthy maintenance diet. Vegetable oils will provide the right fuel for stamina needed for endurance work (aerobic exercise) and should not affect your mare's behaviour. However, in their raw liquid form, oils can be unpalatable and difficult to feed in a sufficient quantity to make a real difference. Triple Top-Up will provide high levels of oil (26%) in a palatable, cooked meal form. It contains lecithin, a fat emulsifier to aid correct absorption. It also has high levels of Vitamin E (3,000 iu/kg) which acts as an antioxidant. Fats are best fed long term, so start with 50g/day and work up to 400g/day, if you are doing rides of 50 miles or more.