Pregnancy losses of 5-24 percent can occur up to 13 weeks after mating. But many older mares won't have foals next spring. Auburn University research shows that mares grazing endophyte-infected fescue pastures have a higher incidence of early embryonic deaths. It's costly waiting until spring to see if mares are open. By spring there's not enough time to diagnose and treat problems before the end of the mating season.
Owners often manage all broodmares the same.
But open and pregnant mares need to be fed and managed differently. With dry pastures and limited hay supplies, determine which mares aren't pregnant and make plans based on your hay supply and pasture. In light of current dry conditions, you may need to cull some open mares to conserve forage for young, pregnant mares with good production records. Consider each mare's reproductive ability, age and the profitability of her foals in making this decision. A 1,200-pound mare needs about 1.5 pounds of hay per 100 pounds of weight, or about 3,200 pounds of hay per mare for six months.