Q. My mare had her first foal last week—a beautiful filly! Everything started out very well. The filly nursed, and my mare accepted her without issue. However, now the foal isn’t gaining weight. I’ve heard that sometimes maiden mares don’t create enough milk. Should I supplement her with milk replacer?

A. Congratulations on the birth of your filly! Having a foal can be enchanting, although at the same time quite stressful because so many things can go wrong. If you haven’t done so already, I strongly recommend contacting your equine veterinarian, who might want to assess the foal and rule out any medical cause for the lack of growth.

Sometimes a mare doesn’t produce enough milk to support the foal’s demands. Foals of this age are nursing in the rage of four to six times per hour, and this suckling action helps stimulate milk production. The demands made on the mammary tissue early on help set the stage for how much milk the mare will produce later. Plenty of early suckling is important so the mare can support the foal’s needs as she grows. If the issue is that the foal does not have much drive to nurse, a veterinarian will need to determine the cause.

If given your vet’s “all clear” to supplement with milk replacer, you’ll find several good commercially produced ones designed specifically for foals. Use these and not replacers created for other species such as goats or cattle. Every species has a milk composition slightly different and unique to their needs.

Because of the need for frequent suckling, feed the foal ad lib milk replacer is best, making sure it’s constantly available. This is better than meal feeding her at times that are convenient for you but perhaps not in sync with when the foal wants to nurse. Also, presenting a foal with infrequent large replacer amounts at once risks overdrinking, and milk might end up in the hindgut where it can disrupt microbial population development.

Keep track of how much replacer the foal is consuming each day. A foal born to a 1,000-pound mare might consume up to 4 pounds of replacer a day, at which point you can transition to free feeding a milk-based pellet.

Make sure you’re creating the milk replacer with a dry matter content of 10%. Less than this level of dry matter might leave the foal hungry. From month one to four the foal might consume 1 pound of replacer per 100 pounds of her body weight. The amount of milk the mare is providing will dictate how much the foal needs to consume from the supplemental source, so don’t be alarmed if you see some variation in how much she consumes each day. Keep a journal so you can see the daily consumption level and be able to identify when you can transition to pellets or to record signs indicating she needs veterinary support.

With careful management and supplementation, you should be able to ensure your foal is receiving the correct plane of nutrition to fully meet her genetic potential and develop at an appropriate rate.