Equine Nutrition FAQ’s – Mare & Foal

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We have a Percheron mare in foal to a Mammoth Jack. She currently weighs about 1,645 lbs. and is overdue one week. Can you tell me what the average birth weight is?

Birth weight estimate for foals is 10% of a mare’s normal weight. The mare will influence the foal size; however, genetics has a more significant influence. The foal maybe smaller because of the Jack’s genetics.

I bought Integrity Growth formula for my rescue mare that is approaching her 7th month of pregnancy and currently lactating. She has a 6 month old filly by her side that is still nursing. I wasn’t clear on your feeding guidelines for a pregnant mare around 1,000 pounds. Should I give her 4 pounds of Growth feed per day? Is it ok to give her that in one feeding (which would be easiest since she is at a boarding stable) or do I need to split it up into two separate feedings?

Smaller meals of a balanced formula are always the better option. For a number of reasons, (digestion, feeding behavior, etc.) two feedings are the suggested minimum. The amount of Growth fed depends on how much hay (forage) is being fed, the type of forage, and your mare’s Body Condition Score (BCS). By foaling, a target BCS score of 6 is desirable because of the high energy demands of the first 8-10 weeks of lactation. Energy demands for early lactation can be twice that of feeding for maintenance. Most of the fetal and some of the supporting tissue growth occurs in the final 120 days of pregnancy.

Milk production (quality & quantity) has significantly dropped off by 6 months of foal age and there is no nutritional benefit to the foal or mare with weaning any later than then 6 months.

Is this protein supplement (protein 31%, starch 24% and sugar 7.5%) safe to feed a 25-year-old pregnant mare with mild Cushing’s and has been foundered?

No, this protein source should not be fed. Old-school products that are not balanced have too much excess sugar, starch, protein, etc. I recommend Integrity Mare & Foal which is a balanced formula. The mare having Cushing’s does present a challenge, and would need to know more about forage, stage of pregnancy to provide the best feeding recommendation.

I have mare who is 6-months pregnant. She is being fed Integrity Adult/Senior due to the high fiber content. She is 11 years old, and I need to know what to give her for the rest of her pregnancy especially referencing copper, zinc, calcium, phosphorus and protein. Any suggestions?

Continue feeding Integrity Adult/Senior to maintain a BCS of 5.5-6. In 90 – 100 days prior to expected foaling, start slowly transitioning to Integrity Mare & Foal. This is a higher protein, balanced formula developed specifically for pregnant mares. Please also refer to this fact sheet with Tips for Feeding Pregnant Mares.

At what age should I stop feeding Integrity Mare & Foal to my foal?

The earliest to transition to Integrity Growth is 10-12 months. Foals by that age have developed the molars for chewing a texture/multiform feed as Integrity Growth. Mare & Foal is higher in the amino acid lysine, slightly higher protein, and has less fiber than Growth. Also, Mare & Foal is a pellet and does not contain beet pulp which may provide some advantage with chewing and consumption during the growth phases after 12 months. My preference is to continue with Mare & Foal to at least 18 months.

Why do you recommend feeding Integrity Growth for the 7th and 8th months of pregnancy and not starting Integrity Mare & Foal until month nine?

I like to continue a pregnant mare on Integrity Growth during the early stages up through the 8th month because the nutritional demands are still low. With Growth, they still get the benefits of beet pulp/soy hulls as fiber sources, the protein-lysine relationship, and lower starch.

Pregnancy length for a mare is 340 days and significant fetal and tissue growth does not begin to take off until approximately day 240 (month eight). The greatest fetal growth actually occurs in the final 60-70 days but you are not feeding just for fetal growth – there is also growth of supporting tissues including the placenta and fluids, as well as the mare’s body/organ tissues that will support pregnancy and lactation.

I have been consistent with recommending to start changing a pregnant mare’s diet at 120 days prior to foaling even when the old National Research Council (NRC) promoted the last 100 days. The reason is that during the 8th month of pregnancy the energy requirements are only 4.9% above the requirements of the mare if she was not pregnant. Less than 5% is not much, but enough difference to emphasize that attention is needed on a diet more than just hay and to be perceptive to achieving a body condition score 6.0.

The new NRC (6th edition) changed their dietary recommendations to 150 days prior to foaling, hence beginning during the 7th month. The actual growth of a fetus and supporting tissue during the 7th month is very small and dietary needs in the 7th month are actually less than a horse on an elevated maintenance diet.

I continue to recommend a higher plane of nutrition beginning the 8th month. It’s okay if you start by the 7th month too though. The nutritional management differences would be feeding less since Integrity Growth would most likely be higher protein and higher fat than the previous diet.

I read that pregnant mares do not need grain, but companies are always marketing grain for broodmares. What do you think?

You are most likely referencing a French study that was presented at a symposium. In the study, 16 lactating mares were grazing what was identified as good quality pasture. Half of the mares only had pasture and the other half in addition to the pasture were fed a barley-based feed. Horses, like most mammals, eat to fulfill their energy needs and we know pasture horses will continue to graze to meet that energy requirement.

Although the study has an intriguing perspective, there are limitations with some of their conclusions:

  • The study involved only 16 mares and they were all the same breed. Sixteen is a small sample size for a study to provide subjective feeding recommendations.
  • The grain was barley-base and provided 60% of the energy requirement during 4 months of lactation. The barley-based feed group of mares actually lost more weight than the pasture-only mares. The authors stated that “weight loss at the end of the study could be due to a variety of factors”. Free grazing fed horses will have a gut content that is heavier than those who consume less forage.
  • The study did not measure intake of pasture, which limits any conclusions that could be considered for practical use. Pasture is about 80% water. More pasture consumption means more water.
  • All the mares were infected with roundworms as a component of the study to determine if nutrition influenced the outcome. Although the study did not note any differences, the roundworm infestation adds a variable that can influence the outcome of the study. Parasites are an immunological challenge that has an energetic cost. That cost is difficult to measure.
  • The authors noted that the pasture-only mares may have consumed and ingested more grass at a faster rate. Perhaps the opposite is true that mares fed the barley grain diet reached an energetic satiety (sense of filling full) and therefore had less grazing vigor.
  • This study’s observation does not agree with a North Carolina State University study in which horses’ total daily feed intake (pasture plus hay, if hay was provided) was not affected by length of turnout time. In other words, horses consumed the same amount of feed regardless of the amount of time they were allowed to graze. The strong ability of mares to ingest green forages explains this result, which is consistent with previous studies. The NCSU study also supported the opinion that horses who have less time on pasture will consume more at a faster rate.

Research is a stepping stone to guide us to a better understanding but caution is always needed when linking a study’s outcome to practical recommendations.

My foals were born in late spring and have done well, but I’ve noticed that the amount of urine has increased since I started feeding them a pellet feed for foals and mares. Why is that?

There are a few factors to consider. A foal’s body composition contains the highest percentage of water at birth; water content in the body reduces with age. Nevertheless, the total volume of water consumed will actually increase during growth, particularly during peak growth. Foals consume higher protein diets and protein contains nitrogen. The foal then drinks more water in order to eliminate the excess nitrogen through its urine.

My friend gives her mare 4-way and lets the foal eat it also. Do you recommend feeding a foal that is still with her mother? Do I feed 4-way to my foal?

Yes, I do recommend creep feeding foals and but do not feed 4-way to your foal. I have added a fact sheet to Dr. Bray’s Corner on creep feeding foals that provides guidelines including feeding protocol and what to look for on a label for basic characteristics of a creep feed. So tab over to the Fact Sheet section in Dr. Bray’s Corner for the Creep Feeding Guidelines.

My mare is going to foal in June. What should I be feeding her? Right now she is being fed alfalfa hay and 2 cups of senior feed.

The 2007 National Research Council (NRC) Nutrient Requirements of Horses energy recommendations for pregnancy are 5 – 8% greater than those published in 1989. The 2007 recommendations also suggest increasing energy intakes above maintenance much earlier in pregnancy, beginning in the 5th month.

Although experience has guided my recommendations that the 1989 reference were inadequate, the 2007 recommendations are higher than I generally suggest. A table is provided that summarizes the energy recommendations for pregnancy compared to the maintenance requirements from the 2007 NRC and the 1989 NRC Nutrient Requirements of Horses.

You should have started feeding your mare a balance formula by at least the 7th month of pregnancy and continue to increase the amounts fed to maintain a body condition score of around 6.0. In the final 3 months of pregnancy the 2007 energy recommendations average 21.3% above a maintenance diet and the 1989 NRC recommendations average were 14.6% above a maintenance diet.

I do not know your mare’s current body condition score or body weight so my recommendations are general. Hay fed in the final trimester of pregnancy should approximate 1.75% of her body weight and a balance formula for pregnancy need to be fed. You will need to review the feeding guidelines listed in the Feeding Guidelines fact sheet in Dr. Bray’s Corner. Any adjustment in her diet must be gradual! Assuming your mare is in good flesh, which is a body condition score of greater than 5 and less than 6.5, then your goal is to feed your mare a balance diet that will supply the energy and nutrients needed to maintain the weight gain that occurs during the final stages of pregnancy. Star Milling has a Mare & Foal that is designed for pregnancy and foals. Another option is to consider a combination (50/50) of Integrity Growth and Star Milling’s Ace Hi Mare & Foal. I like the attributes of the lower starch and higher fiber in the Integrity formula which in combination complements the Mare & Foal formula.

Comparison of 2007 and 1989 NRC Nutrient Requirements of Horses Energy Requirements during Pregnancy

  • Mcal/day – megacalories (a unit quantity of energy) per day
  • 2007 NRC – 2007 National Research Council Nutrient Requirements of Horses
  • 1989 NRC – 1989 National Research Council Nutrient Requirements of Horses
  • % greater than Maintenance – energy expressed as the percentage of energy above energy requirements for maintenance.
I have a 6 month old Quarter filly that was just weaned. Do I need to feed her grain? Can I feed her alfalfa hay?

When a foal hits the ground (newborn) their foregut is ready to handle their only source of nourishment, the dam’s milk. From day one, the foregut of a foal is designed to digest (enzymatically and chemically) the energy and nutrients provided by the milk. However, the hindgut (colon and cecum) will not fully mature, capacity and microbially, until they are approaching 2 1/2 years of age. Hence, providing a growing horse a balance feed mix that supplies feed sources of energy and nutrients that can be processed in the foregut is important in their development. Star Milling’s Integrity Growth was formulated for growing horses from 8 months to 3 years of age. I always recommend creep feeding foals during the nursing phase. If you did and were using a Mare and Foal feed such as the Ace High or Kelly’s Mare and Foal then continue with feeding up to 8 months and gradually transition to Integrity Growth. If the foal has not been on any balance feed formula then introduce a 50/50 blend of the Integrity Growth and the Mare and Foal. Start the foal at 1/2 lb. per day (divide the 1/2 lb. into two feedings) and increase by 1/4 lb. per day every other day until you reach a daily ration of 1/2 to 1 lb. of the blend per hundred lbs. of body weight. If the foal weighs 500 lbs. then feed approximately 3 1/2 to 5 lbs. per day. My general recommendation for alfalfa feeding with foals is not more than 25% of the foal’s total forage feeding per day.

Note: if you are not sure about estimating body weight of your foal, I have added to the Fact Sheet section of Dr. Bray’s Corner, Estimating Body Weight of Growing Foals.

Why do you recommend feeding Integrity Growth for the 7th and 8th months of pregnancy and not Mare & Foal until the 9th month?

The key is to focus on feed ingredients. I like to continue a pregnant mare on Integrity Growth during the early stages up through the 8th month due to the benefits of beet pulp soy hulls as fiber sources, the protein-lysine relationship, and lower starch when pregnancy nutritional demands are still low.

Pregnancy length for a mare is 340 days and significant fetal and tissue growth does not begin to take-off until approximately day 240, which is a little longer than 3 months before birth. The greatest fetal growth actually occurs in the final 60-70 days but you are not feeding just for fetal growth; there is also growth of supporting tissues including the placenta/fluids as well as mare tissues that will support pregnancy and lactation.

I have been consistent with recommending to start changing a pregnant mare’s diet at 120 days prior to foaling even when the old NRC promoted the last 100 days. The reason is that during the 8th month of pregnancy the energy requirements is only 4.9% above the requirements of the mare if she was not pregnant. Less than 5% is not much, but enough difference to emphasize that attention is needed on a diet more than just hay and to be perceptive to achieving a body condition score 6.0. The new NRC (6th edition) changed their dietary recommendations to 150 days prior to foaling, hence beginning the 7th month. The actual growth of a fetus and supporting tissue during the 7th month is very small and dietary needs in the 7th month are actually less than a horse on an elevated maintenance diet. I continue to recommend a higher plane of nutrition beginning the 8th month and if you start by the 7th month that’s ok and the nutritional management differences would be feeding less since Integrity Growth would most likely be higher protein and higher fat than the previous diet.

I have a 2 year old filly which is rather lackluster. The vet did a blood panel and it came back low in calcium and anemic. He recommended feeding her grain for the calcium and a certain commercial product for the anemia. I have read that feeding iron doesn't help with anemia in horses like it does in humans. Should I be feeding something else? Also, I don't want to feed her too many carbohydrates because she is not in training yet. Will Integrity Lite work for her with her condition? I feed it to my 25 year old Arab.

An understanding of your 2 yr. olds feeding program history is needed. The fact sheet in Dr. Bray’s Corner “What to Feed your Horse” will provide the guidelines of the information that is helpful.

Calcium, the mineral that is in the highest concentration in the body and diet, is well regulated in the blood thus total serum calcium is not considered a good indicator of calcium status. That study was conducted in the mid 60’s so even with a diet that is not balanced for calcium, calcium blood levels would remain at a constant level. Forages, common feedstuffs, and balanced commercial formulas provide more than enough calcium but the relationship of calcium with phosphorus and other minerals is critical. The calcium – phosphorus ratio for a 2 yr. old is 1.8:1 (that is, 1.8 parts calcium for every one-part phosphorus). More information on the filly’s feeding program would be needed before I can provide a useful recommendation with calcium intake.

The commercial product you referenced has been around for a very long time and contains a selective group of nutrients but the primary ingredient is an inorganic form of iron (sulfate form). Iron requirements for a 2 yr. old that will reach 900 lbs. at maturity is approximately 430 mg/d and according to that product label, one ounce provides 300 mg. Forages and by-products feeds are considered good sources of iron and iron requirements are easily met by common feedstuffs fed to horses. Iron should not be an issue for a horse that is fed forage and a balance formula such as those in the Integrity product line.

The filly still has some growth to obtain and even after she reaches height maturity, there are body tissue changes that will continue until she is near 4 years of age. In general for a 2 year old, the Integrity Growth formula is the Integrity product that should be fed. You should not be feeding the 2 yr. old filly the Integrity Lite.

I spoke with you yesterday regarding a temporary substitution of Mare & Foal with Growth in our 7 month old foal. I soaked the Growth for 25 minutes as you suggested, but our foal does not like to eat it – probably due to the beet pulp which is quite dominant. Since she does not like it now, my concern is she won't like it at 10 months of age either when we will have to switch from Mare & Foal to Growth. Is there any other Integrity Product that would be suitable for her at that age other than Growth?

She is reluctant because the feed texture in Growth is different than Mare & Foal. That’s why the recommendation for Growth is “from 12 months of age and not earlier than 10 months of age.” It’s important to allow youngsters time to acclimate to any feed, particularly when there are changes in texture. Adding a little brown sugar for sweetness may help along with just being patient. The foal is evolving with experience and this should not be an issue as she ages to a yearling.