Compositional and Nutritional Differences Among Major Forages in the Po Valley: A One-Year Analysis

Forage in the Po Valley is critical to the Northern Italian agricultural economy, providing the foundational feed for the region's intensive dairy sector, particularly for Protected Designation of Origin (PDO) cheeses like Parmigiano Reggiano (PR) and Grana Padano (GP). Dairy production for PR cheese mainly uses forages such as hays since silage is banned to prevent Clostridium contamination and potential swelling defects in the cheese with the lengthy seasoning period. While for fresh milk and GP cheese, maize silage is the mainstay forage base production. The system is characterized by high-input and high-yield, with about 80% of Italy's dairy cattle located here. However, this system faces significant challenges due to high nutritional variability in forage, driven by climatic extremes and management decisions. Accordingly, the objective of this study is to analyse the nutritional composition and variability within each forage species used in the Po Valley. The Regional Breeders Association of Lombardy has been conducting a survey program to monitor forage nutritional composition over the last year (2025). During the last agronomic season (11/2024 – 11/2025), 4250 forage samples were analyzed for their nutritional traits. Nutritional composition was determined by NIRs, while dry matter was determined by oven drying. One third of the samples studied for gross analysis were represented by maize silage; other samples analysed were, in descending order: earlage, grass silage, mixed meadow hay, sorghum forage silage, wheat forage silage, and alfalfa hay. To provide a general overview, two typical forages were considered, namely maize silage and mix meadow hay. As expected the nutritional composition of both maize silage and mix meadow hay were in line with mean values reported in literature. Considering variability within forage type, the most variable nutrient in maize silage was starch with a range of value between 10% and 47%. While in the case of mix meadow hay, the most variable nutrient was protein with a range of value between 4% and 18%. In conclusion, the present study confirmed the extend of nutritional variability in the main forage crop varieties used for dairy nutrition in the Po Valley (Italy). Thus, it is essential to monitor the feed nutritional values for precise nutrition. As a future perspective, long-term nutritional studies are recommended to evaluate the impact of climatic factors on nutrient composition, potentially enabling the prediction of nutrient variability over time.