Seasonal nutritional values of Rubus fruticosus leaves as a sustainable alternative feed for goat in mountain regions

Rubus fruticosus leaves, renowned for their medicinal and veterinary uses, have been insufficiently studied for their nutritional value. This study investigates their chemical composition and ruminal degradability in goats and across seasons. Leaves) were collected from two valleys in the NW Italian Alps at an altitude of 700m, throughout the year (3 samplings/valley/season). Chemical analysis and in vitro tests to measure true and apparent dry matter degradability (TDMD, ADMD), and fiber degradability (NDFD) at 48h were tested using rumen fluid from slaughtered goats. Results revelated the potential of Rubus fruticosus leaves as a promising alternative protein feed with high-fiber compound, but limited NDFD. Seasonal variability significantly affects moisture, crude protein content and degradability. Spring emerged as the optimal season with the highest nutritional value, including the high crude protein content (21.6% dry matter-DM), moisture (76.2% fresh matter), ADMD (50.3% DM), TDMD (73.2% DM) and NDFD (25.0% neutral detergent fiber-NDF). Conversely, mineral and fiber compounds, such as NDF, acid detergent fiber and lignin, remained relatively stable across seasons, averaging 6.3, 37.5, 22.4 and 8.4%, respectively. In conclusion, Rubus fruticosus leaves offer a valuable and sustainable alternative goat feed, particularly in mountain regions, especially during spring. This presents an opportunity to diversify feed resources, reduce reliance on conventional feeds, mitigate the impact of feed shortages and improve the sustainability of the mountain goat production systems.