Calf muesli or the total mixed ration (TMR) for calves contains different types of grain and other ingredients. In addition, different particle sizes of feed are suggested in the literature to stimulate the physical and digestive functions of the rumen and gastrointestinal tract. Coarse particle sizes are recommended to promote fermentation and the development of papillae in the rumen. The feed should stimulate butyrate formation in the rumen and thus promote the development of papillae.

The project will evaluate the nutrient digestibility, fermentation kinetics and microbiome of total mixed rations with different amounts and particle sizes (milled and crushed) of hybrid rye using the rumen simulation system (Rumen Simulation Technique - RUSITEC).

Subsequently, in the following in vivo experiment, the effect of a rye-based total mixed ration on the development of the rumen and the gastrointestinal tract in unweaned calves will be investigated.