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Ask the Nutritionist: Dr. Getty's Forum for Equine Nutrition

   Welcome to my forum. 

Here you will find more than 6 years of questions and my answers. It is searchable and offers a great deal of information. 

Currently, I am discontinuing new questions. This may change in the future, but in the meantime, please know that It has been a true pleasure serving you. 

Take a look at my Nutrition Library and Tips of the Month for a variety of answers on selected topics. Be sure to sign up for my monthly e-newsletter, Forage for Thought

I also have a growing number of recordings on "Teleseminars on Nutrition Topics that Concern You" as well as the new, Spotlight on Equine Nutrition Series -- printed versions of favorite teleseminars.

And finally, look for my articles in a variety of local publications and online newsletters, as well as the Horse Journal, where I am the Contributing Nutrition Editor.  


All the best,

 Dr. Getty 


Ask the Nutritionist: Dr. Getty's Forum for Equine Nutrition
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Breeding Nutrition

I have been reading and doing some research on nutrition for broodmares and foals. It seems like everything I read says a 2:1 calcium/phosphorus ratio is what you strive for. Why then, am I seeing "broodmare" supplements that have a higher phosphorus content than this? Mare Plus is one example, but there are lots of others. I have even read that you can overload on phosphorus, but not calcium. That too much phosphorus can cause deformities in foals that are visible at birth. Please help me understand this.

Thank you

Where are you from? Allegan, Michigan

How did you locate this forum? nutrition search on

Re: Breeding Nutrition

Hi Carrie,

You are correct – the optimum ratio is 2:1 calcium to phosphorus. However, the key to remember (as you mentioned) is that the phosphorus content should never be above the calcium level. Too much phosphorus in relation to calcium can cause skeletal malformations.

What’s interesting is that calcium levels can safely be as much as 6 times more than phosphorus intake. So, you can safely feed hays, even alfalfa (which is high in calcium) and still use a supplement that contains calcium.

Most supplements do not have more phosphorus than calcium. Mare Plus, for example, has between 5.8 and 6.8 percent calcium and 5.0 percent phosphorus, so the ratio is a little more than 1:1 calcium to phosphorus. Select Mare and Foal I, however, has more phosphorus than calcium than phosphorus because it is designed for a high alfalfa diet (which is already high in calcium). If the diet is not high in alfalfa, then Select Mare and Foal II is the appropriate supplement, which is higher in calcium than phosphorus.

You brought up a very important issue. Thank you.

All the best,

Dr. Getty