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Important Nutrition Tips for a Healthy Foal


Providing the right care for your pregnant mare will increase the chances of a healthy foal.

Many pregnant mares are entering their final three months of gestation early in the year. These final three months are a critical time for the unborn foal, because it does most of its developing and weight gain during this period. During the first two-thirds of pregnancy, the mare’s nutrients requirement rise a little, but not substantially. It’s in the final 3 months that the mare’s nutrient requirements rise more dramatically.

Correct nutrition of the mare is fundamental for the health of the foal and unbalanced diets in both the broodmare during pregnancy and the young growing horse may cause irreversible damage later in the youngster’s life.

The pregnant mare – preconception and the first 8 months

For mares entering their final trimester, the following information is too late, but it will be useful for their next pregnancy.

Conception rates are best in mares on a rising plane of nutrition. For that reason, they should be kept relatively lean before covering, so that in the final couple of weeks before covering, they can be turned out to good grass (if available) or fed a good quality forage and compound feed. This practice will increase their condition a little, and aid their fertility. Broodmares should not be allowed to get overweight, however, since this is not healthy.

During the first 8 months of pregnancy, the mare’s nutrient requirements are relatively similar to pre-pregnancy. Exceptions are vitamin A and vitamin E requirements, which are elevated compared to a horse at maintenance. A 500 kg pregnant mare should be fed 30,000 IU of vitamin A and at least 1000 IU of vitamin E daily. Vitamin E should be increased in late gestation (more later).

Protein and energy requirements start to rise at month 5, and then rise more steeply from month 9. Mares should be kept in good (but not fat) rather than lean condition throughout the first two thirds of pregnancy, so that if they have a health challenge they are more likely to get through it without adverse effects on the developing foal and placenta. Research has shown that foals from mares who suffered from an infection that caused weight loss a third of their way through pregnancy were disadvantaged due to a detrimental effect on placental efficiency.

If the mare is in work, she should be fed according to the level of exercise. Workload should be relevant to what the mare is used to, and under veterinary advice. Vets and experts state that it is safe for the mare to be exercised (at a reasonable level) during the first eight months of pregnancy, and this is much better than allowing them to become sedentary and overweight. Most agree that most mares should not be ridden in intense exercise including jumping in the final few months, due to reduced agility and risk of slipping and falling and potentially, uterine torsion.

If the mare does not require a concentrate feed because she is maintaining condition in the first 8 months of pregnancy, then a multi-vitamin and mineral supplement such as ReadySupp Essential Vitamins and Minerals should be fed instead, and the protein quality of the diet considered. If the mare has access to grass her protein requirements should be met. If not, then the forage should have a protein content of around 8% (certainly at month 8) and the lysine content should be 4.3% of total crude protein (hence 34.4 g in 800 g protein).

The pregnant mare – the final 3 months

The mare should be fed enough energy and protein to meet requirements, which would be – for a 500kg horse – about 80 MJ digestible energy (DE) and 800 g protein in month 9, 85 MJ DE and 840 g protein in month 10 and 90 MJ DE and 890 g protein in month 11. The quality of protein is very important, and lysine intake (which reflects quality) should be 34.4 g in month 9, 36.2 g in month 10 and 38.4 g in month 11.

If she gains too much body fat then she is having too much energy and it needs to be reduced very gradually. Feeding excess energy in late pregnancy will not result in a bigger healthier foal, but instead will result in a fat mare. Feeding the mare excess energy may have detrimental effects on the foal’s musculoskeletal health. Researchers have shown higher rates of osteochondrosis (a development orthopaedic disease involving disrupted cartilage development) in yearlings from mares who were fatter and who had higher blood sugar levels during pregnancy compared to mares whose foals were unaffected as yearlings.

Underfeeding energy slightly does not affect birth weight but it may result in a longer gestation than normal.

The developing foal not only requires adequate minerals for ongoing development in utero, but also needs to lay down stores in its own body for use after birth, because the mare’s milk may not supply adequate levels.

The growing foal begins to take up more and more space in the mare’s abdomen, leading to a reduction in appetite in some mares. If this is the case, the forage and concentrate feed needs to be of high nutritional quality in order to fulfil nutrient requirements. Don’t be tempted to overfeed the mare because this can make foaling more difficult and means it will be impossible to raise the plane of nutrition before the mare is put in foal again.

In late gestation, the foetus and the placenta will make up about 12-16% of the mare’s initial bodyweight.

Traditional regimes

Traditionally, a pregnant mare was simply fed a stud mix or cubes. If, however, the mare does not require the energy (calories) from the full recommended amount of such a feed, and therefore is fed less, it will not supply enough vitamins and minerals. As discussed earlier, the micronutrient intake of the mare during the final months of gestation is crucial for the foal’s optimum health.

For example, a mare turned out during the day on grass pasture and stabled at night with hay, who is maintaining condition on a scant scoopful of a traditional stud mix is not receiving a balanced diet and the foal’s health will suffer. This mare must be fed a multi-vitamin and mineral supplement.

How high starch intakes of mares affect the developing foal is not fully understood, but making sure the mare receives no more than 1 g of starch per kilo of her bodyweight per meal (which is the maximum that can be digested properly in a single meal) is recommended. This level equates to about 500 g of starch in a single meal for a 500 kg horse, which is equivalent to about 1.25 kg of oats, or 1.6 kg of a traditional stud mix or cubes.

Mares naturally become temporarily insulin resistant in the final stages of pregnancy, which is likely to be a normal adaptation to ensuring the developing foal receives enough energy. By reducing the sensitivity to insulin in the mare, her tissues are less able to take up glucose, which then becomes more available to the foetus. Care should be taken with mares with a history of equine metabolic syndrome, laminitis and/or insulin resistance and they should fed in the same way as before they became pregnant, i.e. with a relatively low sugar, fructan and starch diet. It is not safe to feed high starch concentrates to meet these mares’ raised nutrient requirements, because doing so might exacerbate their condition and increase the risk of laminitis.

Fulfilling nutrient requirements

Good grass is a useful feed for most mares in late gestation, but may not be available for mares due to foal early. The quality of the forage should be relatively high, especially if the mare’s appetite is reduced. As for all horses, as many nutrients as possible should be obtained from the forage. Hay can be upgraded by mixing with a proprietary, high energy haylage, or adding dried grass or alfalfa. Ensure ad lib forage for all mares except those who are too fat or are gaining too much condition.

Many mares on average forage will require some concentrate feed, but don’t assume they will. Each individual mare needs to be fed according to her own needs, starting with an assessment of her body fat levels. Do not feed stud mix or cubes if the mare is too fat or gaining too much body fat. Feed instead a low calorie balancer or a vitamin and mineral supplement mixed with a source of good quality protein such as alfalfa and soy bean or linseed.

Vitamin E and selenium

Research has shown that feeding mares supplementary vitamin E and selenium over and above normal dietary requirements during their final three months of pregnancy has beneficial effects on the transfer of immunity from mare to foal. Supplementation of these antioxidant nutrients had beneficial effects on the immunoglobin concentration of their colostrum. The foal is born without its own immunity, and gains it from the first milk of the mare – the colostrum. The ingestion of colostrum is absolutely essential for the development of the foal’s immune system, and the foal ideally needs to ingest this within 4 hours of birth to obtain the benefits.

Total dietary levels of the mare should be in the region of 2000 mg of vitamin E and 3 mg of selenium for a 500 kg mare eating about 10 kg (2%) of bodyweight in dry matter per day. A supplement such as ReadySupp Vitamin E and Selenium should be added on top of the basic balanced diet to attain these levels.

The mare should ideally be allowed access to the environment in which she is to foal for a couple of weeks prior to the expected foaling date to allow her to produce relevant antibodies that she can then pass on to her foal in colostrum.

Early lactation

Once the foal arrives, the mare’s nutrient requirements are at their highest. The mare might produce as much as 20 kg of milk per day and her energy and protein requirements rise substantially. She requires double the energy of a horse at maintenance during early lactation. She will produce about 3-4% of her bodyweight in milk in the first couple of months of lactation, dropping to 2-3% in the following couple of months. The mare will produce milk at the cost of her own body tissues, and so weight loss is common. Ideally the mare and foal should be out on good pasture, which is an ideal source of nutrients for the mare, and a healthy environment for the foal. Even good pasture needs to be balanced with a good vitamin and mineral supplement, however.

If good grass is not available, good quality i.e. relatively early cut forage should be sourced, and the mare fed ad lib. Concentrate feed will usually be necessary, and free access to clean fresh water is essential for optimal milk production.

The most important factor is to regularly assess the health and condition of both mare and foal, and adjust the diet and management accordingly.

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