Controlled food trials

Although early studies made important contributions to the field of dental microwear textural analysis, they failed to pinpoint to which extent each food item contributed to the different types of textures. Such issues can only be resolved by the development of controlled-food trials. The TRIDENT project conducts a monitored food testing on several dozens of domestic sheep clustered into different dietary classes. These trials were carried out at a farm under the supervision of the Centre InterrĂ©gional d’Information et de Recherche en Production Ovine (CIIRPO) and the Institut de l’Elevage (Idele). The sheep were kept inside a covered sheep hold, and fed during a minimum period of 70 days. The sheep were not kept on hay, which they would have eaten, but rather on dust-free wood shavings. Feeding troughs were covered with a plastic film and daily cleaned out to avoid contamination. All studies were conducted on cull ewes, meaning sheep no longer suitable for breeding and sold for meat. None of the ewes were put down solely for the purpose of the monitored food test. None of the studies required the sheep to be handled and sheep had full access to foods with which they were familiar.

Each group corresponds to a different diet: clover silage alone to simulate soft leaf browsing, clover silage with chestnuts, barley, or corn (i.e., grains of different size and hardness) to simulate different types for fruit browsing, rye grass silage to simulate grazing habits, and several groups with different proportions of silage to evaluate the effects of different type of mixed diet.

This unique set of dual data (diet composition and dental microwear textures) constitutes the raw data to identify the relationship between diet properties (toughness, silica content, hardness) and dental microwear textures (see figure). Turnover timing of dental microwear textures, exploration of textural parameters, sample size, sampling processes, representativity of a given scan size or dental facet or tooth are explored through this unique dual dataset.

Figure. The controlled food trials on sheep in combination with dental microwear textural analysis on their cheekteeth make up a model in which data issued from fossil species or from modern and wild species may be integrated to interpret their feeding habits.