Agroecological transition may reduce the fat content of Fourme de Montbrison cheese

The Fourme de Monbrison (FM) is a blue type PDO cheese from the French Massif Central area made with unskimmed milk. Since 2011, the dairy farmers are moving towards more agro-ecological practices, promoting in particular a transition from form Holstein to Montbéliarde (Mo) breed and from maize silage to herbage as forage base, maximizing grazing. In parallel, since2018, the share of cheeses having a low fat in dry matter (F/DM) content (< 52% which is the minimum threshold in the specifications of FM cheese) increased and reached 10% and the milk fat content decreased by -0.25 g/kg milk per year, especially at the beginning of the grazing period. An experiment was set up in 20 FM farms to monitor the evolution of milk fat and protein contents and fat to protein ratio (FPR) during the grazing season, in relation to farming practices and herbage characteristics. Milk fat was negatively related to pasture energy content and organic matter digestibility (R < -0.37) and positively to its fiber contents (R > 0.40). Milk protein was positively related to pasture protein content (R > 0.35) and negatively to the time elapsed since the beginning of the grazing season (R = -0.40). This suggest that grazing at an early vegetative stage can depress milk fat content and FPR and therefore cheese F/DM content. The proportion of Ho in the herd was positively related to FPR (R = 0.33) and negatively to milk protein (R = -0.57). In order to tackle these issues, some farmers are willing to test corrective practices in their own farm in the frame of the EU H2020 INTAQT project’s “living-labs” activities.