Body condition is the single most important clue in determining nutrition when aiming for a successful breeding program. For example, I would much rather deal with an obese broodmare than a thin broodmare. When broodmares are thin, their metabolism makes reproduction a luxury she can not afford. To determine the condition of a mare, understanding and implementing a numerical body-condition scoring program is an absolute necessity. The most common scoring system uses grades of 1 to 9 where 1 represents starvation and 9 indicates extreme obesity. The ideal score for broodmares is 6 to 7. Research has shown that mares with less than a 6 body-condition score require more breedings per conception and have more embryonic loss.
Many colleges and extension offices have brochures that detail body-condition scoring. The Equine Research Centre in Guelph, Ontario, has an excellent Website that also details body-condition scoring (http://www.equiworld.net/uk/horsecare/veterinary/erc/conditionscoring.htm). Weight tapes and scales are also good tools to help monitor body condition.
The first trimester of gestation is the best time to improve body condition. This is challenging, however, because many mares are still in lactation from a previous foal, which means they demand great amounts of calories and yet will still lose weight, sometimes leading to embryonic loss. The use of high fat rations of 8 to 10 percent during lactation in addition to high-quality alfalfa hay can prove to be useful.
For obese mares, the second trimester of gestation is the best time to modify body condition. While studies have shown that obesity in broodmares has few negative effects on pregnancy and does not lead to more difficulty foaling, increased feed costs, increased stress on joints and laminitis should be concerns.
“Body condition is the single most important clue in determining nutrition when aiming for a successful breeding program.”
For many years it was thought that 60 percent of foal growth occurred during the last trimester of pregnancy. Based on this, we thought that nutrients didn’t need to be increased until the last three to four months of gestation. However, recent studies have shown that mares can gain significant weight during the second trimester, presumably due to fetal tissue growth. Because of this, mares with a body-condition score of less than 6.5 should be offered improved nutrition during the second trimester.
The last trimester is the time to prepare the mare for lactation. With a rapidly growing foal in the mare’s abdomen, there is a limited amount of space that can be available for intestinal fill, which is why any forage fed in the last trimester must be of the highest quality. The broodmare can ill afford to be consuming a bulky, poor-quality forage with the difference in nutrients to be made up in grain.
If your forages include endophyte fescue, the last trimester is the time to move the mares to a dry lot and offer alternative forages. Many managers will make this move 90 days prior to foaling, but I have been successful with removing fescue as little as 45 days prior to foaling. The toxic effects of fescue clear very rapidly from the mare.
While protein requirements increase slightly as the foal is growing in the uterus, mineral requirements increase greatly. The last three months is a good time to introduce a balanced broodmare concentrate with improved fortification. Now is the time to slowly increase the amount of grain concentrate fed to acclimate the mares’ gastrointestinal tract to the increased grain that will be needed during lactation. Do not, however, abruptly increase the mare’s grain.
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