Feeding selectivity for diet abrasiveness in sheep and goats

Tooth wear can be a considerable factor in shortening the lifespan of herbivores. It is mainly caused by the ingestion of silica particles, either phytoliths - internal to the ingested plants - or external abrasives, such as dust or grit. The avoidance of these abrasives can therefore be favourable to maintain healthy teeth, though it is not known to what extent herbivores are able to select diets based on the level of abrasive contamination. In order to better understand herbivores’ selective capabilities, controlled feeding trials were performed on goats and sheep, offered a choice between high- and low-abrasive pelleted diets. Adding coarse grit resulted in the goats avoiding the diet, whereas the addition of finer dust, yet in high proportion, did not elicit any diet preference response in the sheep. Though preliminary, the experimental results provide an insight into the possible reactions of goats and sheep in response to dietary contamination by external abrasives and suggest that below a certain grain size, abrasives may no longer be detectable by these animals.