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So You Are Expecting?

Equine Podiatry and Lameness Centre - Thursday, June 18, 2020
So You Are Expecting?


It may be your first foal, or you may be an experienced horse breeder but are both you and your mare foaling ready?

Feeding the pregnant broodmare

All too often as an equine nutritionist I see broodmares who are provided with less than optimal nutrition. Their tendency to get fat during pregnancy, especially when grazing good quality pastures means they are often left to eat pasture with only minimal amounts of supplementary feed and in some cases no supplementary feed at all.

While average to good quality temperate pastures can often provide a broodmare with enough calories and protein to maintain her own body condition and provide the calories and protein needed to produce a foal, pasture is also too low in a lot of critical nutrients to provide the amounts needed to produce a sound, healthy, lively foal.

And the problem is, once the foal is born, it is too late to do anything about problems that may have been created during pregnancy. So getting your broodmare nutrition right during pregnancy really is a case of now or never… because once a foal is born it is too late to fix problems that may have been caused by nutrient deficiencies during the pregnancy.

Now or Never

Providing the right nutrients at all of the critical stages of development during pregnancy is really important. It is well known in humans for example, if a woman is folate deficient in the first 3 to 4 weeks of pregnancy the baby has an increased risk of being born with a neural tube defect like spina bifida.If a baby is born with spina bifida, you could give that baby all the folic acid in the world but it (unfortunately) will not help because the damage has already been done several months earlier during pregnancy.

We find similar issues in foals too.Foals born to copper deficient dams have been found to have a significantly increased risk of bone abnormalities such as articular cartilage lesions and worse physitis scores at 150 days of age compared with foals born to mares fed sufficient copper during pregnancy. The really interesting observation made in this study was that copper supplementation of the foals after birth didn’t help the foals born to copper deficient mares, their tendency to have more issues stayed the same… so again, the damage had already been done during pregnancy.

Iodine is another good example of a nutrient you absolutely must get right during pregnancy or it will be too late. Many areas of Australia, including the Hunter Valley of NSW are known to be iodine deficient. Foals born to iodine deficient dams may be weak with a poor suckle response and can also have flexure limb deformities. These little guys will be difficult to nurse through the first few weeks of life and may never fully ‘recover’. In severe cases iodine deficient foals will be born dead so it’s definitely too late to do anything for them.

The point I am trying to make is there are many problems that can be caused by nutrient deficiencies during pregnancy that can not be ‘fixed’ once the foal is born… meaning your only time to get it right is while your mares are pregnant. This means feeding them the right thing, all the way through pregnancy.

Pasture is not enough

Pasture is an amazing source of nutrients, and often it is all a pregnant broodmare may need to maintain an ideal body condition. BUT pastures, and particularly improved pastures, frequently have unbalanced calcium and phosphorus ratios, very low levels of copper and zinc, unbalanced zinc to copper ratios and massive variations in the levels of manganese and potassium.

These mineral deficiencies and imbalances if not corrected will lead to calcium, copper and zinc deficiencies; all of which are known to be implicated in the incidence of developmental diseases of foals including Osteochondritis (OCD). So, while pasture may be enough on some farms to maintain a mare’s body condition and even make her fat, from a mineral perspective pasture is definitely not enough.

Providing the required nutrients is easy enough… sometimes!

The good news is, providing the nutrients we know mares need during pregnancy is easy enough to do. In fact, most well formulated broodmare feeds, when fed at the correct daily amounts, will meet all of the critical mineral nutrient needs of a broodmare provided the pasture she is grazing is not too badly unbalanced.

The problem is, you need to feed your chosen feed at the ‘recommended daily feeding rate’ in order to meet vitamin and mineral requirements, which for most breeding feeds on the market is somewhere around 2.5 to 3.5 kg/day during pregnancy. But we all know that if you feed a broodmare on good pasture this amount of a high-quality feed all the way through pregnancy, she would end up the size of a small house, which is not ideal.

To control body fatness the usual practice is to feed only very small amounts of supplementary feed or in some cases no supplementary feed at all when pasture quality and quantity is good to prevent mares from becoming obese. However, we run the risk of mineral intake and the mineral balance of the diet suffering, potentially put foals at risk. It also potentially puts your mares at risk of declining bone health.To make things even trickier, pasture quality and quantity never stays the same so varying the pasture to supplement ratios will need to vary throughout the year.

So how can you have the best of both worlds and meet mineral requirements without making your mares fat regardless of pasture conditions?

Control bodyweight AND meet mineral requirements… it is possible!

The most successful strategy we employ to allow breeders to control calorie intake and their mares’ body fatness without ever short changing their mares on minerals during pregnancy is to use a breeding feed (that has a recommended feeding rate of around 2.5 to 3.5 kg/day) together with a pasture balancer pellet (with a recommended feeding rate between 0.5 and 1 kg/day) and simply adjusting the amount fed of each one according to the pasture that is available.

When pasture conditions are poor you may find you need to feed a full allocation of the breeding feed. In contrast, when pasture quality is very good, you may feed only the pasture balancer pellet to balance minerals without adding excess calories to the diet. When the pasture conditions are average you may feed a half allocation of the balancer pellet and a half allocation of the breeding feed.

It is important you have your mare on the feed she will be fed post foaling for at least 2 weeks prior to foaling so she and her gut are already adapted to the feed. If you are using just a balancer pellet but will be switching to a feed post foaling, introduce the feed 2 weeks prior to her estimated due date.

To get the best possible handle on what you are feeding, diet analysis using is highly recommended. That way you can remain in full control of what you feed and make sure it is well matched to your pastures!

Now we have feeding sorted, it is time to turn your attention to being prepared for foaling!

Pre-foaling preparations

Foaling down your mare can be an exciting and daunting time for you whether this is your first time foaling or you have been there and done that.In the majority of cases, mares foal down without any issues at all.

First and foremost, it is important to understand when your mare is likely to foal.The horse is a wonderful creature that does not necessarily follow gestational length rules and basically writes their own book on the topic.The average gestational length is around 340 days from the day of ovulation.However, the normal gestational length for mares can be anywhere from 320-360 days.If you don’t know the exact date of ovulation for your mare you may be able to get an estimate from your veterinarian.The most accurate scans are performed within the first 45 days to estimate gestational length and ovulation day as the equine foetus grows at a predictable rate during this time.However, there are some measurements that your veterinarian can perform later in gestation to estimate the age of the foetus.Just remember these are estimates only unless an accurate ovulation date is known.

Due to this great variation in gestational length, it is important mares are watched for signs of birth or parturition for approximately one month prior to their due date.Moving them to the foaling paddock 1 month prior to foaling also allows them to gain immunity to transfer to the foal from the direct environment the foal will be born into.This is also a great time to vaccinate your mare for tetanus and strangles.Immunity is transferred to the foal through the colostrum, the first milk from the udder after birth.If your mare has a caslicks in place, this is also the time to get your veterinarian out to open the caslicks. A quick ultrasound scan at this time is a great opportunity to check the foal’s progress, make sure it is in the right orientation for foaling and to examine the placenta to ensure everything is normal at this stage.Now you are ready for foaling!

Predicting foaling

Some mares will show signs of an impending foaling.Unfortunately, again, not all mares read the book so visual signs of potential foaling can be unpredictable.Signs such as loosening of the vulva and relaxing of the pelvic ligaments, increased udder development and waxing of the teats are all common signs that foaling is near.There are a few milk testing kits available which will help to predict the timing of foaling.Milk calcium steadily increases prior to foaling and can be a predictor of foaling within 24-48 hours.Milk pH declines just before foaling and can be measured using a pH strip with a narrow range of 5.5 – 8.0 (the smaller the increments, the better).A milk pH of less than or equal to 6.4 indicates the mare should foal within the next 72 hours.Using milk calcium and milk pH in combination can more predictably indicate foaling.However, these indicators should be used in conjunction with gestational lengths and are not accurate when the mare has placentitis and/or runs milk prior to foaling.

Foaling alarms are useful and there are a number of different designs on the market.If used in conjunction with milk calcium and/or pH testing, they can ensure that you receive the best nights sleep prior to the arrival of your foal!

The normal foaling

Stage 1:This time usually lasts from approximately 1-6 hours.During this time, you may see your mare shifting uncomfortably as the foetus moves into position for foaling and the cervix dilates ready for passage of the foetus. Usually the signs of stage 1 labour are quite ague and are mostly behavioural such as the mare isolating herself away from other animals, loss of appetite, anxiety, occasional distress.The mare may act colicky at this time, rolling to reposition the foetus.

Stage 2: This is initiated by the rupture of the chorioallantois or the outer foetal membranes.These “waters breaking” can sometimes look like uncontrolled urination as the fluid from around the foetus is expelled.This is then followed by uterine contractions increasing in force and frequency.The foetus moves into the vagina and this initiates abdominal contractions.The mare will usually lay down to facilitate these contractions and expulsion of the foetus. Sometimes mares will get up and down, carefully repositioning the foetus to assist in delivery.This stage usually lasts 5-20 minutes.

Stage 3: Expulsion of the foetal membranes.Mares will usually expel their foetal membranes within 3 hours of giving birth.

When to call the Vet

Ultimately, if you are ever concerned about your mare and her pregnancy, call your veterinarian to discuss diagnostic options and arrange an examination.These are some guidelines that may help.

  • Before foaling
  • If the mare foals before 320 days
  • Gestation length more than 360 days
  • Abnormal udder development or milk secretion well before due date – this could indicate premature foaling or placentitis
  • Any vaginal discharge – this could be a sign your pregnancy is in trouble
  • If you think your mare might have aborted her pregnancy
  • During foaling
  • If the mare is in stage 2 labour for more than 20 minutes
  • If the mare is actively pushing but not making any progress
  • If you find a back leg rather than a front leg
  • If you cannot see/feel two front legs and a head presenting at the vulva
  • If there is excessive tearing or abnormal tissue protruding from the mare
  • After foaling
  • If the mare does not get up after foaling
  • If the mare does not allow the foal to nurse
  • If you think the mare does not have enough milk to feed the foal
  • If the mare has not passed her foetal membranes after 3-5 hours
  • Any abnormal signs such as colic, shaking, sweating excessively etc

My mare has foaled – Now what?

Following the normal foaling, the mare usually stays lying down whilst she re-gains her strength to stand.During this time the umbilicus is usually still attached inside the mare.This will break when the mare stands.We often talk about a 1,2,3 rule when discussing the normal foaling mare.

  • 1 hour:Both the mare and the foal should be standing
  • 2 hours: The foal should have found the teat and be nursing from the udder
  • 3 hours: The foetal membranes should have been expelled from the mare

If there is a failure in any of these stages, then your veterinarian should be notified.

Following foaling, the mare can be administered an ivermectin based drench.Your foal will not require de-worming until approximately 8 weeks of age.After 24 hours it is important a foal examination is performed.Your veterinarian can check all the vital signs on your foal are normal and identify any problems that may require further examination.At this time a blood sample can be taken to check adequate passive immunity has been received from the mare.This test measures immunoglobulin G or IgG in the neonatal foal.This transfer of immunity from the mare is really important.Foals that have a failure of passive transfer are at a much higher risk of life threatening infection.

Feeding the post foaling mare

The most important thing, immediately post foaling is to get your mare eating. Most of the time, if foaling goes smoothly, your mare should have a good appetite after foaling. It is really important to get fibre (hay!) into her gut to refill the void now left by the foal to reduce the risk of colic.

She should also happily eat her normal ration that she was introduced to at least 2 weeks prior to foaling. If she is a little off her feed, try feeds that may be more appealing, like sweetfeeds, or, if she is a fan, a mash made from her normal broodmare feed. If she is not eating, call your vet!

A mare’s calorie and protein requirements will rapidly increase post foaling, so be sure to match the amount you are feeding to her body condition (fatness). If she is losing body condition you may need to feed more high-quality hay (Lucerne is wonderful in broodmare diets to help them help their enormous protein requirement) and additional broodmare pellets.

Happy breeding season!