Controlled feeding experiments with diets of different abrasiveness reveal slow development of mesowear signal in goats (Capra aegagrus hircus)

Abstract

Dental mesowear is applied as a proxy to determine the general diet of mammalian herbivores based on tooth-cusp shape and occlusal relief. Low, blunt cusps are considered typical for grazers and high, sharp cusps typical for browsers. However, how internal or external abrasives impact mesowear, and the time frame the wear signature takes to develop, still need to be explored. Four different pelleted diets of increasing abrasiveness (lucerne, grass, grass and rice husks, grass, rice husks and sand) were fed to four groups of a total of 28 adult goats in a controlled feeding experiment over a six-month period. Tooth morphology was captured by medical CT scans at the beginning and end of the experiment. These scans, as well as the crania obtained postmortem, were scored using the mesowear method. Comparisons between diet groups only showed few significant differences after six months, irrespective of whether CT scans or the real teeth were scored. Only when assessing the difference in signal between start and end did relevant, significant diet-specific effects emerge. Diets containing lower phytolith content caused a more pronounced change in mesowear towards sharper cusps/higher reliefs, while the feed containing sand did not result in more extreme changes in mesowear when compared to the same feed without sand. Our experiment suggests that the formation of a stable and hence reliable mesowear signal requires more time to develop than six months.