Gastric Ulcers and Weanlings: Effects of Diet Type

Gastric ulcers can affect horses of all breeds, ages, shapes, and sizes. Weanlings are among these: They are transitioning from a diet of milk to one of forages and concentrates, while also experiencing the stress of separation from their dams. So, what type of feed should an owner provide to ease the transition's impact on a weanling's GI tract? A team from the University of Illinois led by Kevin Kline, PhD, professor of animal science, recently completed a study in which they determined that a forage-rich diet caused the least amount of gastrointestinal (GI) problems.

Kline and colleagues evaluated the effects of three different diets (an all-alfalfa hay diet, a diet of hay cubes and grain, and one consisting of a pelleted complete feed) on the GI health of 16 Standardbred weanlings (six colts and 10 fillies). The weanlings were divided into two groups of eight (three colts and five fillies each).

Researchers fed each group of horses a different diet during three 28-day periods. Both groups of weanlings were fed the all-alfalfa hay diet for the first 28-day period. Then, researchers fed one group the hay cubes and grain diet and gave the other complete feed for 28 days. The groups switched diets for the final 28 days.

At the end of each 28-day period, each weanling underwent an endoscopic examination to determine the number and severity of gastric ulcers present in the stomach. The veterinarian performing the endoscopic exams was blinded to the weanlings' most recent diets, except for the first round of exams in which all the horses were on the same diet.

"After Period 1 on the all-hay diet, the horses were found to have low ulcer numbers and severity scores, supporting the importance of a high-forage diet in young growing horses," Kline said in the study.

After the next 28-day cycle when the horses began consuming their new diets, the team noted that regardless of whether the weanlings ate the hay cubes and grain diet or the complete feed diet, the number and severity of the ulcers in the weanlings' stomachs had increased by 30%. There was no statistically significant difference between the ulcer scores among horses on these two diets, they added.

On the final endoscopic exams (after the third 28-day cycle), the horses' gastric ulcer scores were nearly three times higher than their base scores. The team said these results suggest that the weanlings did not adjust well to the high concentrate diets.

"This suggests that the gastric ulceration seen in the young horses in this study was a progressive, active pathology extending throughout the 56 days of both high grain diet treatments," Kline noted in the study.

The team hypothesized that "the finely ground pelleted feed required less chewing and might therefore have resulted in reduced saliva production." Because saliva (an alkaline) has a buffering effect on the stomach (an acidic environment), the team believes this imbalance likely contributed to ulcer formation in the stomach.

Previous study results indicated that alfalfa hay also has a buffering effect on adult horses' stomachs. Saliva can't be produced if the horse is not eating; thus, large amounts of time spent with an empty stomach (i.e., between feedings with little to no forage provided) can encourage ulcer development in horses. Therefore, most veterinarians and equine nutritionists recommend continual forage intake for horses.

Kline suggested that if young horses must be pushed to grow and gain weight for reasons such as showing in futurities or in preparation for an early sale, then the feeding of additional processed concentrates should be divided into several small feedings throughout the day and accompanied by plenty of good-quality forages.

Providing a pre-weaning creep feed that contains a high concentration of forage in addition to grain products can help weanlings adjust to consuming some grain before they are weaned. Starting with high-quality forage provides weanlings with most of their nutrient requirements, according to the researchers, reducing their need for additional concentrates.

The study, "Effect of Feed Processing Method on Average Daily Gain and Gastric Ulcer Development in Weanling Horses," was published in the March 2011 issue of the Journal of Equine Veterinary Science. The abstract is available online.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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