BackgroundFeeding alfalfa hay is often recommended for its buffering components, like protein and calcium, to prevent lesions of the gastric mucosa in horses. Until now, there has been no information regarding the influence of alfalfa particle size on the gastric mucosa. The aim of this study was to investigate the effects of feeding two alfalfa preparations with different particle sizes (alfalfa chaff vs alfalfa pellets) in comparison with grass hay on the gastric mucosa in weanling horses. We hypothesized that feeding a high proportion of fine alfalfa particles would negatively impact gastric mucosa and that feeding long alfalfa chaff would improve gastric mucosal health in weanlings.ResultsBefore weaning, the prevalence of gastric mucosa lesions (one or more lesions considering all locations in the stomach) was 84.3 %; at 14 days after weaning, it was almost 100 %. Before and after weaning, most of the lesions were found at the greater curvature of the squamous mucosa and at the lesser curvature. After weaning, gastric mucosal lesions at the pylorus were significantly more severe in the group fed alfalfa chaff (p = 0.002). In the other regions, no differences related to the feeding regimes were observed.ConclusionsFeeding alfalfa failed to improve gastric mucosal lesion scores in weanlings. Furthermore, foals fed alfalfa chaff had higher lesion scores at the pylorus. Alfalfa leaves contain a superior protein source and high amounts of calcium and magnesium, providing extra nutritional advantages in growing horses. At this time, either traditional grass hay rations or grass hay with alfalfa pellets can be recommended.

Summary: Feeding alfalfa hay is often recommended because of its buffering properties associated with substances, like protein and calcium, to prevent lesions. However, the particle size of the alfalfa preparations seems to have an influence on gastric mucosa in weanlings. We hypothesized that feeding alfalfa chaff with harsh particles would negatively impact glandular gastric mucosa in adult horses under maintenance conditions. The study was performed as a cross-over 2 × 2 Latin square design with 16-days washout intervals over 8 weeks. Six geldings (19 to 21 years of age) were kept in individual boxes (10.85 m 2 ). The horses were fed 1.5 kg per 100 kg BW of alfalfa chaff or grass hay, offered twice a day. Horses were subjected to a gastroscopy immediately before the feeding period (T= 0), after the first feeding period of 12 days (T =12), after the first washout period (T = 28), after the second feeding period of 12 days (T = 40) and after the second washout period (T = 56). When horses were fed alfalfa chaff the median score of the antrum raised from 0 to 2 (p = 0.07). And after the washout period the median score of the antrum decreased to 0.5 (p = 0.04). In conclusion feeding alfalfa chaff induced glandular mucosal lesions at the antrum. Lesions of the antrum induced by feeding alfalfa chaff seem to be reversible and to heal within 16 days. Keywords: alfalfa, particle size, gastric lesions, gastroscopy, EGGD, nutrition Citation: Vondran S., Venner M. , Coenen M., Vervuert I. (2017) Effects of alfalfa chaff on the gastric mucosa in adult horses. Pferdeheilkunde 33, 66-71;