It’s a common scenario: Your foal is now a few months old and really thriving while the mare’s looking gaunt. Before you decide this means the foal needs to be weaned early, take a look at the mare’s diet. After all, a mare’s milk is the foal’s perfect food. He’ll benefit from access to it for as long as the mare can provide it.
A lactating mare needs to drink about 50% more water per day than when not lactating. She also needs at least 20% more salt. Her calorie needs go up 70%, meaning you need to feed her like she was a racehorse or endurance horse to avoid weight loss. Grass isn’t enough. You’ll have to increase calorie-dense feedings of grain, beet pulp/bran mash, or added fat. Minerals are an even bigger challenge. Even feeding 70% more calories often does not provide enough minerals and essential amino acids.
If she’s short on the nutrients she takes in, she’ll make up the difference by depleting her own bones and body tissues. This can lead to a host of problems, including weakened bones, tendons and joints, compromised immunity. Fatal uterine artery rupture during labor in older mares has been linked to copper deficiency. Essential amino acid requirements, like lysine, are also doubled.
The easiest solution is to feed at least seven pounds per day of a highly fortified performance or mare/foal grain mix that contains at least 1% calcium, 0.6% phosphorus, 35 ppm copper and 105 ppm zinc.
If you’re feeding your mare plain feeds, she’ll need at least 15 to 20 grams/day of supplemental lysine, 20 to 25 grams of calcium, 13 to 16 grams phosphorus, 90 to 100 mg of copper, 270 to 300 mg zinc and about 240 mg manganese, plus iodine, selenium. These are only average requirements. Your individual mare’s needs may vary depending on details of your feeding.