Broodmare Nutrition: A case of now or never!

Broodmare Nutrition: Now or Never

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 energy and protein to maintain her own body condition and provide the calories and protein needed to produce a foal, pasture is also way 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

Virtually all pastures in the NSW Hunter Valley contain less than half of the copper required by a pregnant broodmare so any mare not correctly supplemented will be copper deficient and will potentially give birth to a foal with an increased risk of cartilage lesions.

Providing the right nutrients at all of the critical stages of development during pregnancy is really very important. It is well known for example in humans that if a woman is folate deficient in the first 3 to 4 weeks of pregnancy (often before she even knowns she is pregnant) the baby has an increased risk of being born with a neural tube defect like spina bifida, where the spinal column never fully develops and can leave the baby permanently disabled from birth. If a baby is born with spina bifida, you could give that baby all of the folic acid in the world once it is born, but it (unfortunately) won’t help because the damage has already been done several months earlier during pregnancy.

Similarly in horses, foals born to copper deficient dams have been found to have a significantly increased risk of 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’t be ‘fixed’ once the foal is born… meaning your only time to get it right is while your mares are pregnant. And this means feeding them the right thing, all the way through pregnancy.

Pasture is not enough

In conjunction with Pryde’s EasiFeed, I have looked at over 400 pasture samples since about 2011 and what we have seen time and time again is 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 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. And depending on your specific pasture, may be causing you more problems than you realise.

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 (many commercial feeds currently available won’t provide very good quality protein, but that is a whole other story!). 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 fed 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.

So to control body condition 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. And this is exactly what you need to do to stop mares from getting overweight. BUT, mineral intake and the mineral balance of the diet is going to suffer and potentially put foals at risk of developmental diseases like OCD and other health issues once they are born.

And to make things even trickier, pasture quality and quantity never stays the same, so while you may have found the perfect feed to use when pasture conditions are average to poor, this same feed can only be fed in very small amounts when your pasture quality is good to excellent or mares get too fat. And there is the between season pasture too that is not great, but not terrible either so mares need some but not a full allocation of your chosen feed. So you will often find yourself feeding less than the recommended amount of your chosen feed which, as we have just discussed, leaves all sorts of mineral deficiencies in a diet and puts your foal at risk of problems that are unlikely to ever be fully reversed, even with the very best nutrition once it is born. 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 stud farms 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. So when pasture conditions are poor you may find you need to feed a full allocation of the breeding feed. When pasture quality is very good, you may feed only the pasture balancer pellet to balance minerals without adding excess calories to the diet. And when the pasture conditions are average you may feed a half allocation of the balancer pellet and a half allocation of the breeding feed.

Let me demonstrate how it works.

The graph below shows the percentage of nutrient requirements that are met for a  550 kg broodmare in late pregnancy fed 3 kg/day of Pryde’s BioMare Cubes together with average quality pasture. This diet meets her requirements very nicely and the digestible energy intake is sitting very close to 100% so she will be holding her weight nicely on this diet.

550kg broodmare on 3kg of BioMare Cube

If you suddenly get a flush of good quality pasture you might find you need to reduce the amount of BioMare Cubes being fed to stop the mares from getting fat. So you reduce the BioMare Cubes to 2 kg/day which does the trick, but look what happens to your mares’ mineral intake.

Broodmare with reducing BioMare Cubes from 3kg to 2kg

So reducing the BioMare Cubes to 2 kg/day has done a perfect job keeping calorie intake about the same despite the better quality pasture (see the ‘Digestible Energy’ has gone from 104% of requirements to 103% of requirements, so it is virtually exactly the same). BUT your mare is now copper, zinc, selenium and iodine deficient. And ALL of these deficiencies will affect your foals in some way.

But if we employ the strategy discussed above and introduce 200 grams/day of Pryde’s 150 Pasture Balancer Pellet we are able to fill in these mineral gaps without changing the mares’ calorie intake (note ‘Digestible Energy’ is still at 103% of her daily requirement). And this achieves our goal of keeping calorie intake the same without creating mineral deficiencies!

Broodmare balanced diet with BioMare Cube and 150 mineral balancer pellet

A feeding program based on these principles would look like this for 550 kg late pregnant mares:

Daily Feeding Rates - 550KG Late Pregnant Mares
Pasture Quality
Pryde's 150 Pasture Balancer Pellets (g/day)
Pryde's Biomare Cubes (kg/day)
600 g
0 kg
Very Good
400 g
1 kg
200 g
2 kg
0 g
3 kg
0 g
4 kg

So when you have excellent quality pasture you would only be feeding only the pasture balancer pellet. When you have poor quality pasture you would be feeding only the breeding feed. And when pasture quality is in the middle you would feed a combination of both products, with the amounts of each depending on the quality of your pasture. And feeding like this means you can control your mares’ body condition without ever compromising mineral intake, allowing you to feed your mares the right way, all the way through pregnancy!

Dr Nerida Richards
Equilize Horse Nutrition Pty Ltd

For an assessment of your late pregnant mare diets, a mineral analysis of your mare pastures or to discuss your needs, contact Pryde’s EasiFeed on 1300 732 267.