- Trainer: Arnold Carb
- Career earnings: $445,780
- Running Style: Eradicates the Pack
- Brief Interesting History: Young at heart, but old in the stomach, Sugar Link has a history of tummy troubles occasionally costing her a race title, but more often than not serving as her surefire strategy. When she feels up to par, she eats up the track demonstrated by her respectable career earnings. Against veterinarian advice, trainer Arnold Carb insists the reason for her success is the result of his specially crafted nutrition plan incorporating high levels of starch into her diet. Her trainer equates the grain ration to an Italian feast of fettucine alfredo topped with sun dried oats and a side of mashed potatoes. This fuels her unique running style of “eradicate the pack”. As Sugar Link turns into the final corner running abreast with the herd, fellow opponents recall hearing a cacophony of gurgles ruminating within her stomach before gripping their mounts manes for dear life as the explosion of methane fires out beneath her tail sending shockwaves of energy that completely obliterate anyone else’s chances of making it to the finish line. It’s a sight to behold as a uniform pack of horses are seen splitting in all directions while Sugar Link pulls ahead for a solid photo finish.
Interpretive Summary: Influence of short-term dietary starch inclusion on the equine cecal microbiome
by Dr. Caitlin Vonderohe
Warzecha et al. (2017) found that feeding grain to cecally cannulated horses significantly affects the cecal environment and the bacterial species inhabiting the cecum in, “Influence of short-term dietary starch inclusion on the equine cecal microbiome” published in the Journal of Animal Science in November, 2017. Equine owners, trainers, veterinarians and nutritionists feed concentrates or, “grain” to horses to provide a more concentrated supply of energy than what would be found in most forages. However, if the horse is provided too much grain, with too many non-structural carbohydrates, that horse can be at risk for gastrointestinal upset. The objective of this study was to characterize what happens to the bacterial populations in the equine cecum when a horse experiences an abrupt diet change that includes high amounts of starch.
The authors used seven previously- cannulated geldings that initially received ad libitum coastal bermudagrass hay. On day one of the study, the diet was abruptly changed and each gelding was fed either a high starch or a low starch grain with continued access to hay. Samples were collected from the cecum prior to the initial morning meal, at 3, 6, 9 hours after the first morning meal, and then 6 hours after the morning meal on days 2, 3 and 7 of the study. After day 7 of the study, the geldings received only hay for 28 days, and then each horse received the opposite (high or low starch) test diet and cecal contents collected similarly to the first part of the study. Each sample of cecal contents was immediately pH tested and then frozen for microbial analysis and measurement of the volatile fatty acid profile.
DNA was extracted from each cecal sample and a section of the bacterial genome was amplified for pyrosequencing. Approximately 672,371 sequences were found and then identified using specially designed software packages. Bacterial diversity, abundance of species, volatile fatty acid concentration, and pH were statistically analyzed based on diet and day of collection.
The researchers found significant changes in bacterial populations in the cecum when horses were fed different diets. Most notably, when horses were fed the diet high in starch there were fewer species of bacteria represented in the cecum. There were also changes in the phyla and families of bacteria present in the cecum which likely drove other changes in pH and VFA profiles that were observed after the diets were changed. They also noted changes in the volatile fatty acids produced in the cecum, particularly increases in propionate when the horses were fed a high starch diet. Cecal pH was decreased after horses were switched to the high starch diet. The authors specifically noted that some of the horses exhibited signs of acidosis even though these horses were fed at levels below what would be expected to cause acidosis.
The authors conclude that abrupt changes in equine diets can cause significant changes in the microbes in the cecum, but also affect the environment of the cecum itself and the general physiology of the horse. The changes observed in the cecal microbiome noted here will help researchers continue to explore the microbiome and the implications of the changes observed in the microbiome in the future.