Pregnant Mares Feeding Changes by the 6th Month

In December, most pregnant mares are at least approaching their 7th month of pregnancy and changes in their feeding program should have started. People often ask, “Why does a pregnant mare need anything different than a pregnant mare in the wild?” The reasons are:

• to optimize nutritional health during pregnancy;
• to maintain a Body Condition Score (BCS) that better prepares the mare for late pregnancy and early lactation stages;
• and then to optimize BCS for mares during postpartum (after birth) breeding to improve conception rate and conditions for embryonic survival.

While pregnant mares in the wild have only forage as a food source, they do have 24/7 grazing opportunity. Feral pregnant mares are dependent on the rain and typical seasonal transitions to provide adequate calories from the fresh forage during the early to mid-stages of pregnancy.

It’s not unusual for a feral mare to have a lower BCS in the final months of pregnancy due to inadequate food. Low BCS at foaling translates to even lower BCS during early lactation, causing pregnancy and foaling rates to decline and is part of the natural population changes that occur with wild animals.

The 2007 edition of the National Research Council’s (NRC) Nutrient Requirements of Horses reported that energy requirements start to increase by 2.4% by the 5th month of pregnancy compared to non-pregnant mares. These recommendations are approximately 5 – 8% higher than previous recommendations.

As an equine nutritionist, I recommend making changes in feeding protocols at 6 months but not later than 6½ months. Fetal growth and growth of supporting tissues are significant by the 6th month and the energy demands increase. The table below provides a comparison of monthly energy requirement increases for an average 1,100 lb. mare during pregnancy.

An 1,100 lb. mare in the first 5 months of pregnancy that is lightly worked should be fed similar to a mare that is non-pregnant. A daily diet for this scenario would approximate 16 – 17 lbs. of hay and 2.5 – 3.5 lbs. of an adult balance formula such as Integrity Mare & Foal or Growth.

By the 6th – 7th months, the average increase in energy demands is near 6%. Feeding a better source of energy, higher protein, fermentable fiber sources and a formula that is balanced for all the required nutrients is essential. By the 7th month, Integrity Mare & Foal should be the only choice. An 1,100 lb. pregnant mare would be fed approximately 20 lbs. of hay and 5.5 – 8 lbs. of Integrity Mare & Foal.