Feeding Broodmares

During a mare’s pregnancy, some significant changes happen that cause her nutrition needs to skyrocket. While bred mares should be fed a quality maintenance diet for the first half of their pregnancy, a maintenance feeding program just won’t cut it after the mid-way point of the pregnancy.

Since we cannot increase the feed intake drastically when the mare foals, she needs to be carrying some extra fat stores so she does not drop body condition drastically before we can bring her up to intake levels that fill lactation energy requirements.  Mares should be at about a body condition score 6 when they foal so that they have sufficient energy reserves for early lactation as well as to maintain condition for re-breeding. If she is in a significant negative energy balance (losing body condition) she is much less likely to rebreed easily and carry the next pregnancy.

To bring a mare along properly in her nutritional journey, here are some general guidelines to keep in mind:

  • Good quality pasture or forage may provide sufficient energy thru late gestation, but may not provide adequate amino acids and minerals. 
  • A ration balancer product or a feed designed for pregnant mares may be used from month 5 to about month 10 or 11 of gestation to provide the missing nutrients. 
  • A feed designed for broodmares and foals should be introduced prior to foaling, so that the mare is properly adjusted to the feed well before she foals.  She is under quite a bit of stress immediately before foaling, so this is not the time to be introducing a new feed. This feed can then be increased after foaling to provide both the increased energy and the increased nutrients that are required for lactation, as well as providing nutrition for the foal when it starts to nibble on feed. 
  • Fresh clean water and free choice salt should also be available at all times.
  • The mare should also be vaccinated properly before foaling so that her colostrum, the rich first milk, contains antibodies to protect the foal.  Proper nutrition will also help immune response to vaccinations.

During lactation, a mare’s energy needs are easily doubled over her maintenance needs, and while a mare is producing milk for her offspring, her water consumption can exceed 50-100% that of a maintenance horse. Around 13-24 weeks after the mare has given birth, her milk production will begins to decrease, and the diet can start to be cut back slightly as nutritional needs are getting back to those of a normal maintenance horse.

Feeding the broodmare properly can help reduce the risk of developmental problems for the foal and help insure that the mare can be rebred in a timely manner to produce another foal the following year.

Inside the Broodmare’s Belly…

Lactation demands a lot from a broodmare!

Are you anxiously awaiting that first foal of the spring? Do you have the foaling stall ready, the vet on speed dial, and the video camera on the battery charger? While you’ve been busy prepping, here are some of the amazing changes that have taken place (or are about to take place) in your mare:

  • 6 Month Mark: During 2nd half of pregnancy, 60 – 65% of fetal growth occurs!
    • Energy requirements of the mare go up almost 30% over a normal maintenance horse – from 16.7 Mcal DE per day to 21.4 Mcal DE per day.
    • Her protein requirements will increase 32%, and vitamin and mineral requirements also increase significantly during this time.
    • The mare needs to be receiving adequate calcium, phosphorus, magnesium, copper, zinc, manganese and selenium to provide minerals for the development of the foal and to build the foals own trace mineral reserves.  Trace minerals are also critical for immune support. 
    • Adequate protein/amino acid intake is essential – lysine, methionine and threonine, the first 3 limiting essential amino acids, need to sufficient in the diet for placental and fetal development.
  • Last Trimester: The average foal fetus will grow by 1 pound per day!
  • Lactation: After the foal has been born the real work for the mare is just beginning.
    • The normal mare will produce around 24 lbs (3 gallons) of milk per day. During an average 150 day lactation, this equals 450 gallons or 1.75 tons of milk!
    • During lactation, a mare’s energy needs are easily doubled over her maintenance needs – from 16.7 Mcal DE per day to 31.7 Mcal DE per day!
    • While a mare is producing milk for her offspring, her water consumption can exceed 50-100% that of a maintenance horse.
    • Around 13-24 weeks after the mare has given birth, her milk production will decrease from 3% of her body weight to around 2%.

With all that effort going into producing a darling new foal for your farm, be sure to give your mare an extra pat on the neck, and of course, make sure you are feeding her properly!

Nutrient Deficiencies in Horse Feed Diets

Horses, like all animals, have a range of nutrient requirements to meet their daily needs.  These are spelled out as minimum nutrient requirements in the Nutrient Requirements of Horses, 6th Edition, published by the National Research Council of the National Academy of Science.

If these minimum requirements are not met, the horse may experience deficiency symptoms.  The severity of the deficiency symptoms may depend on the degree of the deficiency and the time period over which the deficiency exists. 

  • A sub-clinicaldeficiency may be the result of a small deficiency over a period of time. 
    • Subclinical deficiencies may also result in decreased immune response, decreased reproductive efficiency and decreased performance.
  • A clinical deficiency is present when there are readily observed or measured symptoms.

Perhaps the easiest example is a deficiency of energy (Calories) in the diet.  The more severe the deficiency, the faster the horse will lose weight.  If a horse is losing a quarter of a pound per day, the loss will take some time to be visible. Over the course of 6 months, the horse would lose 45 pounds or about a full body condition score.  Over the course of a year, the horse is almost 100 lbs underweight or goes from a body condition score 5 to a 3.

If the horse is getting sufficient Calories, but is deficient in protein or essential amino acids, the body condition might appear OK, but the hair coat might get dull, the hoof quality might deteriorate and the muscle tone might be lost.  This is common for horses that are on pasture that has adequate energy content, but is short on amino acids or other nutrients.  If the diet is deficient in key fat soluble vitamins such as A, D and E, it might take longer for the deficiency symptoms to show up as the animal will use up stored vitamins first.  If there are mineral deficiencies or imbalances the symptoms might show up in either bone problems or reproductive problems.

Mineral imbalances can create deficiency symptoms as well.  A diet that contains a large excess of zinc might produce symptoms consistent with copper deficiency.  An excess of phosphorus, creating an inverted calcium to phosphorus ratio (less than 1:1), can produce nutritional secondary hyperparathyroidism or “Big Head” disease as well as other bone issues.

The diet below illustrates a diet that might produce some sub-clinical issues over time.  This is a fairly typical grass hay and oat diet and uses basic NRC requirements for an 1100 lb horse at light work.

Percent of nutrient needs that are met with a traditional horse diet of oats and hay.

Offering salt free choice would take care of the sodium (Na) deficiency, but there would still be some trace mineral and vitamin shortages in the diet.  The extra magnesium in the diet would not be expected to be a problem.

Using a ration balancer horse feed product would be one solution. Using a properly fortified commercial feed that contains meets all of the requirements when fed as directed would also be a good way to prevent the development of clinical or subclinical deficiency symptoms.

Horse Feed: More Than Just Percentages

A hanging scale, such as this (dirty) one is helpful to hang a bucket from and weigh feed. Note that the scale has been tared for a bucket.

Horse owners frequently compare feeds based primarily on the information on the feed tag or supporting data from web sites.  While this is a quick comparison to make, it may not always be the best comparison.  Why, you ask? Well, what is most important to the horse is the total amount they actually consume.  To get this number, the percentage in the feed must be multiplied by the amount fed, making sure to account for different unit of measurements, such as supplements that are fed in ounces instead of pounds.

One example where this is important is with the protein percentage.  As ration balancer horse feed products are becoming more and more popular, some folks see that they typically have 30% protein or more, and worry that the level is way too high for a horse.  But with a ration balancer, a 1000 lb horse only gets 1-2 pounds of the product a day, compared to 4-6 lbs of a more traditional 12% feed.  So, if we do the math, here’s what we see:

  • 30% protein X 2 lbs of feed = 0.6 lbs of protein a day from a ration balancer
  • 12% protein X 5 lbs of feed = 0.6 lbs of protein in a day from a traditional feed

Another example where this calculation is useful is in the variety of fat supplements available on the market today. 

  • A powdered fat supplement has 99% fat, being fed at a rate of 2 oz a day, adds 0.124 lbs of fat to the daily diet.
  • A stabilized rice bran supplement that has 22% fat, fed at a rate of 2 lbs per day, adds 0.44 lbs of fat to the daily diet.

And of course, on top of this, we must ALWAYS remember to factor in the hay – not just the grain.  A horse will consume much more hay per day than grain, so the difference in a few percentage points is magnified when looking at the hay portion of the diet.  It may take a little math, but looking beyond the percentage of a particular nutrient is something your horse would thank you for if he could speak!