Informative, Inspirational & Aspirational

Informative, Inspirational & Aspirational

Nutrition – July 2019

Managing the mums:

Animal nutritionist LARISSA BILSTON explains why the higher nutritional requirements of pregnant and lactating mares is so important.

As we move into spring, many brood mares move into their final months of gestation signalling higher nutritional requirements. Have you thought about what you’ll need to feed your mare from now until she foals? And what will she need to eat after the foal is born? 

Provided your mare was in good condition, and being fed a well-balanced forage-based diet supplemented with high quality protein and a vitamin and mineral supplement to fill any gaps and correct mineral ratios, her dietary needs will not visibly alter much for the first six months of pregnancy. However, if she is lacking in energy or vitamins and minerals, her body will ‘mine’ its own resources to give these to the growing foetus. 

Roughage is always the basis of a healthy ration: The first rule of good horse nutrition is to feed plenty of roughage – pasture, hay or chaff.  Unless your mare is overweight, it is safe to feed as much grass-based roughage as she will eat. If your mare needs an energy source such as digestible fibres, grains or pellets to continue in light work or to maintain weight, then you should continue to feed that to her and carefully monitor her body condition. Your mare needs to be a healthy weight (not too heavy, not too light) to maintain a healthy pregnancy, but her body’s requirement for energy throughout pregnancy only increases slightly and gradually over her need when spelling or in light work.  

Add the appropriate amount and type of protein: Pregnant, lactating and growing horses need high quality protein in their diets – especially lysine, a key amino acid they are unable to produce in their bodies. Lucerne and soybean meal are often an effective option for adding lysine to breeding horse rations and are commonly found in commercial feeds formulated for breeding horses. Pure lysine can also be purchased from bodybuilding stores and added as a supplement in carefully calculated amounts. Chart 1 illustrates that during the last three months of pregnancy your mare will need almost 50% more lysine than she did before conceiving (a 600kg mare needs 46g of lysine/day at 11 months gestation).  

Your pregnant mare’s need for some minerals is higher than when spelling and in some cases, is higher than when performing very heavy exercise. The main increases for mineral requirements relates to calcium and phosphorous, which are needed in increasing amounts as the pregnancy progresses; and for copper, iron and iodine in the last 3 months. As with mineral supplementation in all classes of horses, it is imperative that your pregnant or lactating mare obtains all the minerals she needs, in carefully balanced ratios from all food sources. 

Feeding the lactating mare: After foaling, your mare’s protein and energy requirements are higher than at any other time in her life. It is not unusual to have to feed more hard feed, in a more energy dense form, than she has ever needed before. Even given this she may still lose weight during the first months of lactation. Unwanted weight loss can be minimised by feeding three or more small hard feeds per day in addition to all the quality hay and pasture she can eat.  

Your mare’s energy and protein requirements will begin to drop after the foal reaches three to four months of age because milk production starts to decline. However, the amount of food going into the mare and foal unit often stays almost constant until weaning to allow the mare to recover any body condition lost during early lactation and to feed the foal who now eats more grass, hay and hard feed and drinks less milk. 

A lactating broodmare may consume as much as 50% of her daily intake as concentrate. It is also critical to provide a vitamin and mineral supplement to satisfy your mare’s daily requirements and to correctly balance the mineral ratios across her entire diet. Remember to check whether your supplement contains salt, and if not, add 10g of plain salt (sodium chloride) per kg of bodyweight to the daily ration. 

Do I need to feed a commercial breeding horse pellet?: A quality breeding specific commercial premixed feed can simplify feeding for some mares, but only if she eats the full daily recommended amount of the feed. If she needs more or less calories than the feed provides, you will need to adjust the protein and mineral levels to avoid an oversupply or deficiency. For this reason, in many cases it can be simpler to provide a protein source and a quality vitamin and mineral supplement separately from the energy source. This allows you to easily change the diet in response to seasonal changes as well as your mare’s changing needs through pregnancy to lactation and weaning. 

If I mix my own concentrates, what sorts of feed should I use? 

Extra energy to top up calories from roughage if required from: 

  • Super Fibres – energy sources that are high in digestible fibre make an excellent basis for adding calories to the diet of broodmares. These include beet pulp (e.g. Speedibeet, Mircrobeet), soy hulls (e.g. Maxisoy), other legume hulls such as lupin hulls or Hygain Fibressential which is a blend of ‘super fibres.’ Copra is also high in fibre but is also relatively high in fat.
  • Legume grains – the most commonly available is lupins which can be fed in a processed form or if bought whole or cracked and soaked in water to soften prior to feeding.
  • Cereal grains – oats contain starch in a form which is easily digested by horses when fed raw. Oats can be fed whole provided your mare’s teeth are in good condition, but other cereals such as barley and corn are poorly digested unless cooked (boiled, extruded, micronized or pelleted). Cereal by-products such as wheat, bran and millrun are lower in energy and nutrients than whole grains.
  • Fats and oils – can be used judiciously to boost the energy density of lactation diets but must be introduced very gradually to avoid upset.

Extra protein to top up amino acids – especially those high in lysine from: 

  • Lucerne, clover or other legumes in the hay or pasture.
  • Full fat soybean meal.
  • Pure lysine as a supplement.
  • Other common feeds such as lupins and copra are relatively high in crude protein, but their amino acid profiles are not as well matched to horse requirements.

Vitamins and minerals:

  • A quality vitamin and mineral supplement rich in macrominerals, trace minerals and vitamins. Look for one designed to balance mineral ratios across the whole diet.
  • Consider a probiotic live yeast (Saccharomyces cerevisiae) shown to boost forage utilisation and milk production.

Conclusion: Roughage (pasture, hay or chaff) forms the foundation of any well-balanced horse diet. Not all pregnant mares require an energy source (like grain, beet pulp, oil, pellets, formulated blends) especially in the first two-thirds of gestation – it depends on how they hold their weight and the energy content of their roughage source, and that varies according to seasonal factors. Some may need an energy boost when pasture is not growing well, but won’t need any added energy during the spring pasture flush. Others may need a steadily increasing amount of hard feed over the pregnancy.  

Your mare’s energy and protein requirements will reach an all-time high during the first half of lactation and she may need three or more meals a day to supply her milk production. As the foal starts eating more grass, hay and hard feed and drinks less milk, the mare’s feed requirements begin to reduce gradually.  

If you feed a bagged ‘complete feed’, you’ll need extra vitamins and minerals when you feed less than the recommended amount from the bag. If you mix your own hard feeds and incorporate a comprehensive all in one vitamin and mineral supplement you can easily make changes to the energy and protein content of the diet as necessary.  

Remember to provide clean water at all times and to make all dietary changes gradually, and introduce new ingredients over a two week period to allow gut microbial populations to adapt.  

It can be a wise investment (for your pocket as well as your horse’s health) to seek the advice of a qualified equine nutritionist during these critical stages of the life of your mare and new foal. 

You can find out more from Larissa Bilston about Equine Vit&Min products on their FB page: and their website:  

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