Beautiful Winter Coats
In order to do its insulating job properly, your horse's winter coat needs to have a degree of fluffiness to it. It won't lay flat and sleek like a seal's in winter. However, it can, and should, still have vibrant color and a smooth texture.
Not devoting as much time to grooming as during riding season, mud and the greater difficulty of grooming a dense winter coat are all a part of the problem. Curry comb and stiff body brush are a must but as you know that often just seems to make them dirtier. This is where a vacuum is your new best friend. Horse vacs are pricey but even a household hand held vacuum can do a good job for an investment of $100 or less. Just be sure to do your homework and check reviews for best suction and good action on pet hair.
Lack of exercise also has a negative effect on skin and coat. Exercise reduces the cold induced low blood flow to the skin. When the horse sweats, it also spreads protein and fats to the coat. If the horse does not vigorously self-exercise, try to schedule formal exercise a few times a week, even if it's just 15 minutes of a brisk trot on the lunge.
On the nutrition end, there are two big differences between hay and pasture - fat and vitamin A. As hay ages, these losses get even worse.
Every kilogram (2.2 lbs) of hay has at least 20 grams (roughly 3/4 ounce) less fat than fresh grass. For the average horse eating 2% of his body weight in hay per day, it comes to a 7.5 to 8 ounce fat deficit. If you are feeding grain, some of this deficit may be filled from that source. Any grain fat level above 3% represents added fat. A 5% fat grain has 2% added fat so pound per pound it will supplement fat for the same amount of hay. If feeding 1 kg of 5% fat grain you are covering the fat deficit for 1 kg of hay so can subtract that from the total hay amount. For example, subtract 1 kg from 10 kg of hay for a total of 9 kg remaining hay with reduced fat. To calculate how much fat you now need to supplement, multiply by 2% = 180 grams of fat = 6.3 ounces (28.4 grams/oz).
Fat keeps the skin pliable and helps avoid skin flaking and a dry, brittle coat. Maintaining a good fat level improves the ability of the outer layer of the coat to repel water. The omega-6 essential fatty acids are also important for maintaining a good immune system protection in the skin.
Vitamin A has a growth hormone-like effect on skin cells and hair growth, promoting normal turnover of cells. It is also important for normal immune defense in the skin and the secretion of normal skin oils. Deficiency causes skin dryness and flaking, plugging of hair follicles and a dry coat. It will also make the coat slow to shed.
Vitamin A is routinely added to feeds and supplements but activity can be reduced by 50% in as little as 9 weeks after manufacture under very warm storage conditions. Feeds sold within their shelf life (about 3 months) probably have minimal loss of vitamin A but supplements labeled for longer shelf life may suffer reduced activity. Aim to supplement 40,000 to 50,000 IU of vitamin A, subtracting the amount in supplements and feeds from that total to determine additional A needed.
Zinc is important to the function of vitamin A. It is required to convert A from the diet into forms that are active in the horse's body. Zinc levels don't change when grass is dried to hay but they are often deficient. Supplementation with 600 mg of zinc, and 200 mg copper to avoid copper suppression from zinc, is reasonable.
Grooming, regular exercise and a few nutritional adjustments can keep your horse's winter coat as healthy, shiny and attractive as at other times of the year.