Most easy-keeping horses can thrive on forages alone, but others, such as broodmares, need additional feedstuffs to meet their daily nutrient requirements. | Photo: iStock

Most easy-keeping horses can thrive on forages alone, but others, such as broodmares, need additional feedstuffs to meet their daily nutrient requirements. Highly palatable and digestible grain-based concentrates can help supply calories as nonstructural carbohydrates (NSC), most being starch. Because too much starch can upset horses’ gut microbial balance, a research team at the University of Kentucky (UK) sought to determine if starch source affects fecal levels of these microbes in broodmares.  

Normally, enzymes in the foregut (everything ahead of the large intestine) act on NSCs to aid absorption. If all the NSC is not digested, it spills over into the hindgut, negatively affecting the microbial environment and leading to hindgut upsets and potentially colic. As part of her graduate research in the Department of Animal and Food Sciences, Morgan Pyles and a UK team compared the effects of oat-based (OB) or corn- and wheat-middlings-based (CWB) pelleted concentrates on fecal amylolytic (capable of breaking down starch), cellulolytic (capable of breaking down cellulose), and Lactobacillus spp bacteria in mares prior to foaling through post-foaling.

Eighteen Thoroughbred mares took part in the study from 310 days gestation through four weeks post-foaling and were randomly assigned to either the OB or  CWB concentrate. Mares received 3.2 kilograms (7.05 pounds) of their respective concentrate per day prior to foaling and 4.8 kilograms (10.58 pounds) per day after foaling. Researchers collected fecal samples from mares two weeks after starting their assigned diet prior to foaling and at Day 1, 14, and 28 post-foaling to determine the number of cellulolytic, Lactobacillus spp, and amylolytic bacteria present