Tag Archive for: mare

Mare on pasture with foal at foot

Retained Placenta and Selenium Deficiency

Retained placenta… bad luck? Or is there more to it?

I am going to say there is definitely more to it. And if you look to the cattle industry they agree. And a lot of it comes down to one little mineral… SELENIUM!

I was recently at an Animal Nutrition conference at the University of New England. One of the speakers, Prof Michael Lee (University of Bristol) spoke about selenium. Here are a few photos I snapped of his slides:

Listed at the top of his list of symptoms of selenium deficiency in ruminants was retained placenta. And this is certainly what I see in horses too.

Almost the only time I see retained placenta as a widespread issue is on breeding farms that do not supplement pregnant mares.

The most recent case I dealt with was a farm with more than 100 standardbred broodmares. At the time of my first visit, the mares were not supplemented at all during pregnancy.

And retained placenta was occurring in 25 % of mares! 1 in every 4 mares were experiencing this potentially life threatening complication! Eek!!

I suggested that if they supplement with selenium (as part of an overall balancer pellet) that this shouldn’t be such an issue.

They decided they would experiment. And gave half the mares the balancer pellet. The other half they left unsupplemented.

The results were clear. The supplemented mares had one mare in 60 with retained placenta. That is less than 2%… a big reduction from 25%!

The unsupplemented mares had 2 retained placenta within the first 4 mares that foaled! This was enough to convince the farm that maybe we were onto something… so rather than keep going with the experiment they very quickly put all the mares on to the balancer pellet!

The interesting thing for me was that the incidence of retained placenta dropped almost immediately in this group of mares who were initially unsupplemented.

The nutrition of your pregnant mares is so important. This is just another reason you should pay close attention to mineral nutrition, especially because selenium is a mineral that is often low in forages and is therefore often deficient in diets.

For more about feeding pregnant mares click here to read our post ‘Feeding Pregnant Mares’.



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Do Phytoestrogens Affect Mare Fertility?

In a word, yes, phytoestrogens affect mare fertility! Both industry observation and published science support this. BUT, we need to be very careful not to just throw all phytoestrogens (which are simply estrogen like compounds found in plants) into the one bucket.

There are many different phytoestrogens, but they don’t all affect fertility. Some, like coumestrol, mainly found in alfalfa/lucerne and clover have quite dramatic negative effects on fertility in multiple animal species, including horses. Others, like the isoflavones found in clover and soybean are not documented anywhere (that we can find) as having negative effects on fertility in mares.

A Few Things To Consider…

There is quite a lot documented on loss of fertility in sheep grazing pastures dominated by isoflavone rich clover. But we need to consider several things:

1. A sheep’s gastrointestinal physiology is dramatically different to a horse and likely affects how phytoestrogens are absorbed and metabolised.

2. A sheep’s reproductive tract physiology is also very different, meaning phytoestrogens are unlikely to affect fertility in the two animals species in the same way; and

3. The sheep were consuming isoflavone rich forage. i.e. the ingredient containing the isoflavone was the major ingredient in the diet. Consider ingredients like soybean in a horse’s diet.

Yes, they contain isoflavones, but they are only fed as a small percentage of the total daily diet. So actual isoflavone intake is minimal… so negative intakes on fertility are far less likely.

Not All Phytoestrogens Are The Same

When looking at phytoestrogens in feed ingredients you may be using and considering their potential impact on fertility, keep in mind phytoestrogens from different ingredients aren’t the same. And that the amount of an ingredient you feed per day will affect total phytoestrogen intake. And also remember that almost every feedstuff you feed can potentially contain phytoestrogen, even grasses!

And the tricky thing with forage phytoestrogens is that both the plant variety and the environmental conditions it is grown in will affect its phytoestrogen content. For example, clover or lucerne that is attacked by aphids will have a higher coumestrol content. Or nitrogen deficiency in clover can have double its normal isoflavone content.

Complex huh!

If your mares are experiencing fertility issues it is certainly worth considering phytoestrogens, but as always, look at your basic nutrition first to make sure your mares’ most important nutrient needs are met.

FeedXL can help you do this! (If you’re not yet a member, check out our plans here)

If you do think phytoestrogens may be to blame, from my reading I would suspect your forages first, especially if you are using clover or lucerne/alfalfa. It is highly unlikely other ingredients like soybean or flax that are typically fed in much smaller amounts will be your culprits.



Do you have a question or comment? Do you need help with feeding?

We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!

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Feeding the Lactating Mare

Getting a lactating mare’s feeding right is critical to ensure she can provide milk for her foal and provide the required nutrients for a foetus if she is pregnant again. A balanced diet is also essential to keep the mare healthy so that she can continue to reproduce or go back into work after her foal at foot is weaned.

As for all horses, a mare’s requirement for energy (calories), protein, vitamins and minerals must be met. These nutrients and the role they play in a lactating mare’s diet are looked at below.


A lactating mare’s requirement for energy is double that needed by a mature idle horse.

Not feeding a lactating mare enough energy means she will lose weight. If she falls below a condition score of 5 (on the Henneke 1 to 9 scale), it may make it difficult to get her back in foal and could also reduce the amount of milk she produces for her foal.

If she is allowed to exceed a condition score of 7 her milk production may fall and it also puts unnecessary pressure on her joints and hooves which will cause pain and lameness for the mare.

The basis of a mare’s energy intake should be provided by pasture and/or hay. If pasture and/or hay is not enough to maintain body condition, high energy feeds like cooked cereal grains, high energy fibres and oils can be added to the diet.

To manage energy intake, you should condition score your lactating mares regularly and adjust their energy intake up if they are losing weight and down if they are gaining weight.

Protein and Amino Acids

Lactating mares need good quality protein to enable them to provide milk for the foal and to maintain their own muscle mass. Not enough protein in a lactating mare’s diet will cause milk production to fall and the mare will begin to lose muscle.

The majority of the protein in the mare’s diet should come from the pasture and/or hay the diet is based on. When there is not enough protein in the pasture/hay to meet a mare’s requirements, good quality protein sources that are rich in essential amino acids such as soybean, lupins, faba bean, canola meal and lucerne or feeds based on these ingredients should be used to meet requirements. Poor quality sources of protein such as cottonseed meal should always be avoided in lactating mare diets.

Because the NRC 2007 lysine requirements (used by FeedXL.com) are now quite high many of you will find that lysine requirements are quite difficult to meet, especially for mares grazing lower quality pastures including the sub-tropical C4 Type pastures. I find the best way to help with meeting lysine requirements is to first add some Lucerne hay to the diet to replace some of the lower quality forage she is eating. Then with this better source of lysine coming from the forage base you will find it a lot easier to meet lysine requirements using appropriate high quality feeds.

Vitamins and Minerals

Vitamins are extremely important in the lactating mare’s diet and have an impact on the mare’s health and fertility as well as the foal’s growth, muscle development and immune function. Mares with access to green pasture will have the majority of their vitamin requirements met by the pasture alone. Mares with no access to pasture will generally need to be supplemented with vitamins.

A lactating mare has massive requirements for minerals, and particularly for the macro-minerals calcium and phosphorous, which are found in large quantities in milk. It is also important to meet her requirements for trace minerals as they are required to ensure the structural soundness of her future foals.
Not meeting the lactating mare’s requirements for minerals will mean her body reserves are depleted, leaving her susceptible to disease and lameness. Mineral deficiency can also reduce her milk production and fertility and can affect the soundness of future foals.

A lactating mare’s mineral requirements will be partially met by the forage/hay in her diet. However, it is unlikely a mare’s full mineral requirements will be met, so some supplementation will almost certainly be necessary.

Vitamins and minerals can be supplemented in the form of a concentrated vitamin/mineral supplement or in the form of a complete feed, depending on your preference for style of feeding and how much feed your mare needs to maintain body condition.

If your mare is an easy keeper, using a concentrated vitamin/mineral supplement will allow you to provide the vitamins and minerals she needs without providing additional calories that could make her gain unneeded weight. Well formulated balancer pellets are particularly useful for these mares. On the other hand, if your mare is a hard keeper, it would be easiest to use a complete feed that provides the mare with additional calories and protein as well as providing the vitamins and minerals she needs.

Which is the best feed for your mare?

When choosing the right feed and developing a feeding program for your lactating mare(s) you need to consider the following:

  1. Do you have pasture available?
  2. What sort of pasture do you have and what is its quality like?
  3. Will your mare maintain bodyweight on pasture alone, or do you need to feed additional feed for her to maintain bodyweight?
  4. What hay do you have available and what is its quality like?
  5. Is your mare an easy or hard keeper?
  6. Does she need to gain, maintain or lose weight?
  7. What stage of lactation is she in?
  8. Do you prefer to feed a complete feed or mix your own feeds using supplements?

The answers to these questions will determine whether a complete feed or a supplement is best for your mare and will also help you determine what amount of feed your mare needs. If your mare is a hard keeper or if you have very little or only poor quality pasture available a complete feed will most likely be needed. If you have good quality pasture and/or your mare is an easy keeper you may find a vitamin/mineral supplement is all that is required.

Regardless of what you choose to feed, ensure your lactating mare always has free access to forage in the form of pasture or hay, a salt lick and very clean, fresh water.

FeedXL It!

FeedXL will help you put together a balanced diet that meets the energy, protein, lysine, mineral and vitamin needs of your lactating mare to ensure that she remains healthy and productive during this phase of her reproductive cycle.

And just as importantly, FeedXL will allow you to accurately create diets for your growing foal. A growing horse’s requirements are constantly changing and the future soundness and health of your foal really depends on you getting nutrition right in the formative years of its life. So don’t guess at what you should be feeding (please). Investing a little time now on a good diet for your mare and growing horse can save you a lot of time, frustration and heartache in the future.

Meet The Author: Dr Nerida McGilchrist

Dr Nerida McGilchrist is FeedXL’s co-founder and equine nutrition specialist. She holds a degree in Rural Science, a doctorate degree in equine nutrition and nearly 20 years of full time, on the ground experience in feeding all types of horses. To learn more about Nerida and to ‘meet’ the rest of the FeedXL team, check out our About Us page here.



Do you have a question or comment? Do you need help with feeding?

We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!

Click here to join the FeedXL Horse Nutrition Facebook Group

Horse eating from hand

Feeding Pregnant Mares

Pregnant mares carry your hopes and dreams, be it for the next big champion or just a quiet riding companion. Regardless of what you are breeding, good care of the mare during her various stages of pregnancy has long term impacts on both her and her foal’s long term health and athletic capacity.

Here are some tips for feeding pregnant mares to keep them healthy and breeding sound, strong and athletic foals:

1. Don’t let mares get fat

Mares in their early stages of pregnancy don’t need many, if any additional calories than they needed when they weren’t in foal. All mares are different, so to really know how much feed your pregnant mares need you should condition score regularly. Pregnant mares should ideally be maintained at a condition score of 6 and should not be allowed to exceed a score of 7. Having mares too fat can:

  • Reduce their milk production when they foal.
  • Put unnecessary strain on their hooves and joints, making them heavy and uncomfortable.
  • Lead to difficulty foaling (though this isn’t necessarily proven to occur).
  • Make it difficult to fall pregnant again, particularly if a mare is forced to lose weight just prior to or immediately following foaling.

As mares progress through their pregnancy their requirement for energy and protein does increase, so you may find you need to feed additional feed to maintain their body condition score. For more information on Condition Scoring read our FeedXL Newsletter #1. If you are feeding pregnant mares, get in the habit of running your hands over them every time you feed them. Doing this means you will quickly pick up if they are putting on more condition than they need and will allow you to adjust their feed intake accordingly.

2. Don’t let mares get skinny

A pregnant mare shouldn’t be allowed to drop below a condition score of 5. Mares that are any lighter will fall away quickly after foaling, reducing the body energy and protein reserves for milk production and also switching off the reproductive cycles, making it difficult or impossible to get in foal again. Thin mares may also be more susceptible to disease.

Again, get in the habit of running your hands over your mares to assess whether they need more feed to hold them in the desired body condition. If you notice their ribs becoming easier to feel or their topline and rump starting to fall away, you will need to increase the amount of feed they are getting. Because so much room is taken up in the mare’s abdomen late in the pregnancy you will likely need to feed high energy grains (make sure they are cooked—see FeedXL Newsletter #18) or high energy fibre feeds that use ingredients like sugarbeet pulp or soybean hulls to allow them to increase their energy intake enough to hold their body condition. High fat feeds are also useful for late pregnant mares.

3.­ Make sure mineral and vitamin requirements are met

Meeting the mineral and vitamin requirements of pregnant mares during early and late pregnancy is crucial to:

  • Promote the sound development of their foals.
  • Prevent deficiencies like iodine that can affect the thriftiness and survival of newborn foals.
  • Prevent problems in the mares like retained placenta and the associated laminitis.
  • Maintain a strong immune system in the mare and foal.
  • Maintain the long‐term health and soundness of the mare for future reproduction.

While pregnant mares can often be maintained on good quality pasture with little additional feed, without supplementation of minerals, a pasture‐only diet will almost certainly have quite dramatic deficiencies of copper and zinc and depending on the geographical location may also be very deficient in calcium, phosphorous, magnesium, iodine and selenium.

If the mare doesn’t receive the additional minerals she needs to support herself and her growing foetus she will draw them from her own body reserves. However if she is required to do this for many consecutive breeding seasons it will eventually have implications for both her and her future foals’ long‐term health, soundness and athletic ability. One study has shown that foals born to mares early in her breeding career have less structural problems than foals born later in that mare’s life, which may indicate that over consecutive pregnancies, mares can run out of reserves of minerals that directly impact the sound development of her foals.

FeedXL allows you to quickly and easily determine your mare’s requirements for these critical minerals as well as vitamins and helps you make sure the diet you are feeding is meeting her requirements through all stages of pregnancy.

4. Feed high quality protein

During pregnancy a mare requires high quality protein to meet her own requirements and those of her growing foetus. If the pasture your mare is on is of low quality (for example sub‐tropical C4 Type pastures, or pasture that has matured, gone to seed or browned off), add some high quality alfalfa/lucerne hay to raise the quality of protein in the forage component of her diet.

If you are using supplementary feeds on low quality pasture, select feeds that use legumes and oilseeds with quality protein, including soybean, lupins, faba/field beans and canola meal. Low quality protein sources like cottonseed meal shouldn’t be used for pregnant mares. FeedXL will help you make sure you are feeding enough good quality protein to your mares to produce healthy foals and will also stop you from overfeeding protein which will make your mare’s diet very expensive.

5. Make the most of pasture if you have it

Pasture is an excellent source of energy and protein. Feeding a diet that relies largely on pasture has two main positive effects. The first is it will make for an economical diet, with pasture being one of your cheapest feeds available. Secondly, a high fibre diet will keep your mare’s gastrointestinal tract healthy, reducing the risk of problems like colic (something to be avoided in a pregnant mare).

To really know what is in your pasture and what your mare needs in addition for her diet to be balanced, you should have your pasture tested for energy, protein and minerals levels. Once you have had your pasture tested we can enter the results into your FeedXL account so you can see what is in and what is missing from your specific pasture. Then you only need to add what is missing from the mare’s diet. Equi‐Analytical can run a full analysis starting at $26 USD. It is well worth the investment. If you rely on hay for your mare’s main source of forage this too can be tested and the results put into FeedXL.


Because it is so often said that a pregnant mare needs little more than a horse at maintenance, it is sometimes mistakenly thought that mares and particularly early pregnant mares can be fed diets of forage only with little or no supplementation. However while a pasture or good quality hay diet may be sufficient to maintain your mare’s bodyweight, it will almost certainly be lacking in critical nutrient including minerals that can determine if your foal is born structurally sound or not.

Keeping mares in the correct body condition, making sure you meet mineral and vitamins requirements from day 1 of the pregnancy, feeding high quality protein and using pasture when you can will help you to breed sound foals that are healthy and full of life when born. It will also mean your mares can remain healthy and able to produce strong foals with good structural soundness year in, year out. Being pregnant may not appear to be hard work, but it will take a toll on your mare’s body if she is not properly cared for.

Meet The Author: Dr Nerida McGilchrist

Dr Nerida McGilchrist is FeedXL’s co-founder and equine nutrition specialist. She holds a degree in Rural Science, a doctorate degree in equine nutrition and nearly 20 years of full time, on the ground experience in feeding all types of horses. To learn more about Nerida and to ‘meet’ the rest of the FeedXL team, check out our About Us page here.



Do you have a question or comment? Do you need help with feeding?

We would love to welcome you to our FeedXL Horse Nutrition Facebook Group. Ask questions and have them answered by PhD and Masters qualified equine nutritionists and spend time with like-minded horse owners. It’s free!

Click here to join the FeedXL Horse Nutrition Facebook Group

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