Trade-offs between milk production potential, tannin content and plant diversity depend on grassland mixtures

Summary in the original language of the document

Temporary grasslands are crucial for addressing dairy cow sector challenges, including milk production, methane emissions mitigation, and biodiversity enhancement. In this study conducted in Frick, Switzerland, we investigated four distinct temporary grassland mixtures, replicated across 16 plots. These mixtures comprised: 1) pure grasses, 2) a combination of grasses and legumes, 3) a combination of grasses and tannin-rich plants, and 4) a combination of grasses and plants rich in essential oils. Over the course of six grazing rotations in 2022, our research encompassed botanical surveys and vegetation chemical analyses for each mixture. We calculated three pivotal variables: the potential milk production for a hypothetical dairy cow, the plant species diversity, and the condensed tannin content. Principal component analyses (PCA) were employed for each mixture to highlight the tradeoffs among these variables. Grass mixture correlated potential milk production with species diversity. Essential-oil mixture correlated milk production to tannin content. Grass-legume and tannin mixtures traded species diversity for tannin content. These findings underscore the importance of designing specific temporary grassland mixtures at the plot and farm scale to effectively address the predominant challenges facing the dairy cow sector.