Getting Ready for the Breeding Season

by Leesa Nacht

Nutrition For Stallions and Broodmares

Breeding can be a complicated issue, albeit Mother Nature is quite amazing in taking care of things. One of the easiest and most obvious variables that can be controlled is that of nutrition. Let’s have a look at both the broodmare and the stallion, during the time that is now upon us - coming into the peak season of breeding activity.

The Broodmare:

You’ve taken the plunge into being a broodmare owner. There are many management decisions to be made with respect to the nutritional composition of the diet you feed your mare (and the foal-to-be).

During the initial stages of pregnancy, the first two trimesters, the nutritional program of the mare is not dramatically different from that of a horse doing light work. Do not be tempted to reduce the intake of an obese mare at this time. Research shows that pregnant mares receiving a reduced energy level have a greater incidence of abortion in the first three months of pregnancy than those who receive adequate energy. Any attempts to change the weight of the mare should be made in early fall of the year prior to parturition. The ideal body score should be about six, meaning a moderate to fleshy look, some fat over the ribs and just the beginning of fat being deposited along the withers, behind the shoulders and along the neck.

Current research shows that the fetus does go through rapid growth during the first 90 days of gestation, but there is not much accumulation of mass. The demand on the mare is minimal. The fetus grows most rapidly during the last trimester, with 60 per cent of its growth occurring at this time. This is when you really need to be conscious of the mare’s diet. Some experts believe that the plane of nutrition should be increased earlier than this, but if you are feeding a balanced diet up to this point, with adequate vitamins and minerals, you should be able to avoid problems.

During the entire period of gestation, the mare’s weight should increase about 12-15 per cent. The foal accounts for 8-10 per cent of that weight, with the remainder attributed to the placenta and placental fluids.

The diet in the third trimester should be slowly increased in terms of protein levels, energy content, and the vitamins and minerals must be supplemented in the correct proportions. A safe rule of thumb is to increase dietary intake by about 10 per cent per month throughout the last trimester. If the mare is receiving inadequate nutrients from her diet, she will ‘rob’ her body of what is needed for the foal. This can leave you with an underweight mare, impinging on her lactation abilities. A mare produces about three per cent of her body weight in milk per day. This translates to 15 kg per day for the average 500 kg horse. While very little affects milk composition, the levels of protein in the over-all diet can affect the amount of milk produced. (See Table 1)

Table 1:

% Crude Protein 9 11 12.5

Milk kg/day 11.8 12.6 10.8

As with any diet, one must first take into consideration the composition of the forage. Fibre is important to maintain efficient digestion, but during theses last months, the mare would probably do better with a more energy dense, less bulky ration. The enlarged womb decreases digestive capacity. During the last trimester, the average intake is only about two per cent of body weight, down from earlier levels of 2-2.5 per cent. Table 2 shows the some of the major nutrient requirements of a broodmare’s diet, assuming that the mare is 500 kg (pre-pregnancy weight):

Table 2:

Protein Energy Calcium Phosphorous

12-14% 20-24 mcal/day* 0.45-0.5% 0.3-0.35%

* (1 mcal = one thousand calories)

It is essential that adequate amounts of calcium, phosphorous, zinc, manganese and copper be supplied to the mare in order to ensure proper development of the unborn foal. Phosphorous deficiencies can also lead to reduced fertility in the mare after foaling and reduced milk production.

Once the mare foals, the real crunch is on. She now has the greatest demands being made of her body, due to lactation. Compared to late pregnancy, the mare’s requirement for energy increases by up to 70 per cent, protein by up to 60 per cent, and calcium by up to 65 per cent over her previous needs. The mare will now eat close to three per cent of her body weight each day. She also has increased needs for vitamins and minerals to ensure her continued good health, encourage milk production and to give the foal all that it needs. Nutritional stress at this time will first affect fertility, second, milk production, and finally the body condition of the mare. Do not worry about the mare losing weight. Weight reduction through restriction of feed can result in reduced milk production, affecting the health and development of the foal. Table 3 shows the average nutrient requirements at this stage:

Table 3:

Protein Energy Calcium Phosphorous

14-16% 30-35 mcal/day 0.48-0.52% 0.3-0.33%

If you are in doubt about your mare’s nutritional program, consult with your veterinarian or a qualified nutritionist. There are so many factors that influence the health and well being of your foal - genetics, environment, among others - that controlling the nutritional program of your mare can help to reduce the risk of an unhappy ending.

The Breeding Stallion:

In order to help your stallion perform to his best, there are some basic principles to follow with nutritional and management procedures. Very little research has been done on the relationship between nutrition and breeding stallions, but there are still some good guidelines to follow. One of the biggest influences on stallion performance is management.

Because the stallion is used for only a portion of the year, he needs to be fed at two levels of intake, one for the off-season, and one for the breeding season. During the off-season, the average stallion should be kept on a well-balanced diet, with the requirements being similar to that of maintenance to light working levels. This would be a similar diet as fed to a barren mare. The ration should contain 12 per cent crude protein, and be supplying the stallion with about 23 mcal per day. As recommended with all horses, the diet should always contain a minimum of one per cent of body weight of forage. Maintenance diets usually contain closer to two per cent of body weight in forage. If you are feeding first class forages, the need for more expensive concentrates is reduced. Not only is this economical, but it is a healthier way to feed your horse. Another benefit of feeding a high forage diet (free choice) to a stallion is the reduction in boredom, due to the increased time required to eat forages over concentrates. Boredom can be a very serious problem with stallions, leading to detrimental behaviour such as masturbation, and in extreme cases, self-mutilation.

Many stallion managers increase the plane of nutrition during the three to four weeks prior to the commencement of breeding season. It probably doesn’t hurt to put a few extra pounds on the stallion, provided you don’t over do it. As with the mare, the ideal body score for a stallion at the start of the season is six. This extra weight will usually get worked off fairly quickly from the increased stress and excitement at the beginning of the season. The diet at this point should be similar to that of a horse in light to medium work, with increased energy levels (28 mcal/day) and a crude protein level of about 14 per cent. Generally, the stallion will be consuming about 2.5 per cent of his body weight in feed. A guideline would be 1.5 per cent of body weight in forage fed with one per cent of body weight in concentrates.

An example of how to adjust the ration from the start of the season until the end would be to feed a 70:30 forage:concentrate ration at the start, say 12 lbs. of hay and five lbs. of concentrates. As the season wears on and the demands on the stallion are greater, the ration could go to 60:40, with 12 lbs. of hay and eight lbs. of concentrates.

Under Feeding & Over Feeding

There are some problems associated with both underfeeding and overfeeding of a stallion. Gross underfeeding can result in testicular atrophy, poor semen quality, reduced sex drive, and abnormal sperm production. Many of these symptoms are also seen in stallions suffering from hypothyroidism, a deficiency of the thyroid hormone. If you suspect such a problem, contact your veterinarian for diagnosis.

Overfeeding can also be a problem. Overweight stallions show signs of slow sexual performance, a decreased libido, and even impotency. Another serious problem that can arise from obesity is the degeneration of the sperm-producing tissues. This is caused by fat deposition in the scrotum, which in turn causes abnormally high internal temperatures. Something to keep in mind with all overweight horses, not just stallions, is that there is an increased risk of laminitis, or founder, occurring. Ideally, any diet adjustments should be made during the off-season, so as not to cause stress to the animal. Increased exercise is another method of reducing body weight.

Vitamin and mineral levels in the diet are similar to that of working horses as well. Vitamins A and D should be supplemented, especially if the stallion is housed during the day (not exposed to sunlight) and if he is eating grass hay. Grass hays, like timothy or bromegrass are low in vitamin A, while legumes such as alfalfa, are naturally high. Suggested levels would be 4000 IU/kg of feed of Vitamin A, and 1000 IU/kg of feed of Vitamin D. As mentioned earlier, the breeding stallion has many similar requirements as a working horse, so extra levels of vitamin E would serve to satisfy this parameter, increasing from 100 IU/kg of feed in the off-season to 200 IU/kg of feed during breeding season. Most of these requirements can be met by using a good quality commercial feed.

Though poor nutrition can result in many fertility problems, mismanagement of the stallion is the most common reason for abnormal performance. There are many ways management can influence the productivity of your stallion, and the importance of having a good stallion manager or handler cannot be stressed enough. Rough handling, abuse, overuse and inadequate exercise can all contribute to creating behavioral and performance problems. Even during the rigors of breeding season, stallions should be exercised lightly, either through turnout or light longe work. Off-season, many stallions are ridden to keep them physically fit and relieve their boredom.

By caring for your stallion’s special needs, you will help to keep him productive as well as manageable. He may very well be the foundation of your breeding business, and should be treated as such.