However, during the last 3 – 4 months of pregnancy, the foal begins grow and develop more rapidly. In fact, during the last 90 days of pregnancy, developing foals gain approximately 1 lb per day. Considering the average foal weighs 100 – 110 lbs at birth, 90 of those pounds happened in the last 4 months of gestation. This rapid development requires significant nutritional support to lay down the foundation of bones, muscles and tendons. The only way to provide this nutrition to the fetus is through the mare so it is critical to provide her with the proper balance and quality of protein, vitamins and minerals during this time. The increased size of the growing foal also takes up room in the mare’s body cavity such that she may actually eat less hay or forage. This reduction in forage intake, coupled with the increased nutritional needs, means mares in late gestation should be supplemented with a nutritionally-balanced concentrated grain ration. Even in situations where forage alone is maintaining mares in acceptable body condition, it is important that they receive quality concentrate supplementation. While good quality forage may be able to provide sufficient calories to maintain body condition of the mare, other nutrients such as protein, vitamins and especially trace minerals, will be deficient.

While body condition certainly affects reproduction efficiency and health of the mare, having mares in good condition doesn’t guarantee proper foal development. Body condition is directly correlated with calorie intake but doesn’t necessarily reflect intake of protein, vitamins and minerals. Research has shown that foal birth weight can be negatively affected when mares fed inadequate protein during late gestation, even when mares were maintained in a fleshy condition. It is not uncommon to see fat mares have small, weak foals when the mare’s diet was adequate in calories but low in quality protein. Even when mares are fed high protein forage, like alfalfa, the diet can be deficient in important amino acids and other nutrients. Late gestation mares should be fed a grain mix or supplement containing quality protein sources that will meet amino acid requirements fo r optimal foal development.

During the tenth month of gestation the greatest amount of mineral retention occurs in the unborn foal. Mare’s milk is practically devoid of trace minerals that are essential for proper bone development, such as copper. Forages, including pasture and hay are also low in trace minerals. Therefore, adequate trace mineral supplementation of the mare is critical for normal fetal development. Feeding a ration with the proper trace mineral balance during late gestation will meet the mare’s requirements and provide sufficient minerals for the developing foal. In the first weeks of life, foals will not eat sufficient amounts of fortified feeds and may not have adequate absorption of dietary trace mineral sources at this early stage of development. Proper mineral nutrition of the mare in late gestation helps insure that the developing foal will actually store a supply of these important nutrients for use after he is born. This will bridge the time from birth until foals are old enough to consume and assimilate these important nutrients from a well-balanced foal feed.

If a mare is thin during late gestation, meaning her ribs can be seen, this is the best time to provide enough calories in her diet to facilitate weight gain. It is nearly impossible to put weight on a lactating mare, and thinner mares, especially those nursing a foal, are less likely to become pregnant when rebred. This means that late gestation is the last chance to get a thin mare in good shape. In these situations, select a feed that is very calorie and nutrient dense, in order to supply the needed energy and nutrients to support weight gain without having to feed excessive amounts of grain.

While research has shown that fat mares don’t have a higher incidence of foaling difficulties, they may have a reduction in milk production which can negatively impact foal growth. If a mare is significantly overweight during late gestation, where ribs cannot be seen and are difficult to feel, you must provide adequate protein, vitamins and minerals to support optimal fetal development without adding unnecessary calories. In these cases, choose a concentrated protein, vitamin, mineral supplement that is designed to be fed at 1 – 2 lbs per day. This type of supplement will meet the nutrient needs of the foal without causing weight gain in the mare. It may be necessary to restrict hay intake to 1.5 lbs of hay per 100 lbs of body weight in significantly overweight mares in order to facilitate weight loss.

Proper nutritional management of the broodmare during late gestation will give her foal the best start in life. With all the time and money invested in getting a mare in foal and all the promise and potential that comes with a newborn foal, you don’t want to skimp on mare nutrition during this critical time.

Karen E. Davison, Ph.D. – Manager-Equine Technical Services Land O’Lakes Purina Feed

All hay, regardless of type or presentation, must first be judged by quality. It is important when deciding on a hay source to gain a full knowledge of the type of grasses involved in the bailing process. Hay should be clean, with little dust and free of debris such as wire, rope, trash, mold and weeds. Hay, regardless of type, when bailed should be fairly uniform meaning all the blades of hay should look like they belong to the same type of plant. If there is a large percentage of weeds this decreases the quality of the hay and may increase the possibility of irritants such as stickers or spear grass. Other factors influencing quality include time elapsed since it was bailed, method of storage, maturation at time of cutting, as well as temperature at time of cutting. Samples may be sent to your local county extension agent for quality analysis.

These things established, let’s address the possibility of a round bale. A round bale is often more cost effective and less management intense than using square bales. If a square bale and a round bale, both bailed from the same cut with the same nutritional analysis were fed in the exact same amount to a horse, they would both meet the roughage requirements. A common problem associated with round bales for horses is overeating to the point of colicking. Horses, with all of their wonderful attributes, are lacking in a bit of wisdom for self preservation-a horse can literally eat itself to death. For this reason, it is important that care is taken in introducing a horse to the round bale. The ideal method of starting a horse on a round bale is to place the round bale in the pasture while there is still good grass. Most horses will prefer good grass to good hay and will limit their initial intake of hay. As the pasture dies, the horse slowly replaces the roughage intake of grass with that of hay. A common fault in using round bales is waiting until all the grass is dead. At this point, the horse is craving a good source of roughage and when it is given a round bale it will often overeat to the point of colic. If the pasture is gone by the time you start to feed hay, this situation can still be avoided by simply keeping the round bale in a separate area and allowing your horse limited access to the bale which is then gradually increased to allow the horse’s digestive tract to adapt to the new hay. Be careful that the horse does not go without hay for any length of time between round bales as this can also set them up for overeating once the new bale arrives.

These are some suggestions to make feeding round bales safer for your horses. All horses are different and some will tolerate certain management practices better than others. If good quality hay is fed in a reasonable management situation, round bales may be an acceptable option. If you have any questions, you should contact your equine veterinarian to discuss the best options for your horse.

Maria Wilson, DVM
Rockwall Equine Center
972-524-6616