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-The aim of this study was to verify the variation in fatty acid composition of milk, and derived cheese, when dairy cows were grazed on different alpine vegetation types. An experimental design was developed to highlight the effect of pasture composition on milk and cheese fatty acid profiles, thereby mitigating the other variables (altitude, animal physiology, and animal management). Two dairy cow groups were grazed on two different key alpine vegetation types (Type 1: Trifolium alpinum, Nardus stricta, and Carex sempervirens and Type 2: Festuca nigrescens, Alchemilla xanthochlora, and Phleum alpinum). Bulk milk was collected separately from each group for 6 days, from which 12 artisanal cheeses were produced and ripened for 60 days. The fatty acid (FA) composition of the bulk milks and cheeses varied with the type of vegetation. Milk and cheese derived from cows that were grazed on Trifolium alpinum-dominated pastures were richer in long-chain FAs, unsaturated and monounsaturated FAs (particularly oleic acid), and odd-chain saturated FAs (such as C15:0 pentadecanoic and C17:0 heptadecanoic acids) while those from Festuca nigrescens pastures contained more short-and medium-chain FAs, saturated FAs, and α-linolenic acid. Furthermore, our results showed that in alpine grazing systems, milk and cheese FA profiles changed when cows were grazed on pastures with a different botanical composition, probably due to differences in forage quality and concentration of bioactive secondary metabolites. These results have to be taken into account for the valorization of the nutritional characteristics and for the traceability of grass-fed dairy products.fatty acid / milk / cheese / grassland biodiversity / alpine pasture / grazing acide gras / lait / fromage / biodiversité des pâtures / pâture alpine / pâturage

Thermal time (Tt, °C days) was used to quantify germination, emergence and leaf appearance of temperate grassland species from natural and commercial seed populations. Germination requirements of six clovers (Trifolium arvensis, T. dubium, T. glomeratum, T. striatum, T. subterraneum, T. repens) were determined from constant temperatures from 5 to 35°C. The base temperatures (T b ) were all less than 2.5°C, except for B. erectus (5.8°C). The four grasses had slower rates of germination and a wider tolerance of high temperatures than the clovers. All five annual clovers had a lower thermal time requirement for emergence and seedling development than the perennial T. repens. For four of the species used, the internationally recommended seed testing procedures that requires prechilling was found to be unnecessary and for two others the currently recommended optimum temperatures are higher than the optimum found. The thermal time approach has provided a robust summary of large datasets generated from controlled and field conditions. These easily transferable coefficients can be used to quantify seed and seedling responses to temperature for individual species and should form the basis for redefining seed testing regimes.

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