Reducing feed-food competition: impact of by-products and grazing in ruminant feeding

World population and global food demand are expected to increase in the next decades. Although some improvements have been achieved, livestock sector remains a major contributor to the impacts of agriculture. One of the sustainability themes that has recently seen an increasing interest is the conflict between feeding edible crops to people or to livestock. Large amounts of cereals and legumes used in conventional systems could instead be used more efficiently by monogastric animals or be consumed directly by humans. Therefore, reducing human-edible crops in animals’ diets represents a promising way to increase the sustainability of ruminants with noticeable ethical implications. Two indicators are available in literature to assess the potential human-edible content in animal diets. In two experimental trials carried out with dairy cows, these two indexes improved significantly both when hazelnut skin, a by- product from hazelnut industry, was included in the diet of cows and with increasing level of grazing in mountain dairy farms. Ruminants play a major role in food supply chain: thanks to the microbiota in the rumen, they are able to convert fibrous feedstuffs (unsuitable for human consumption) into high valuable and nutrient-dense food (i.e. milk and meat), with increased nutraceutical quality of the products if grass or by-products are used. Moreover, the use of grasslands and pastures by ruminants, especially when land is unsuitable for crop production like in mountain areas, provides ecosystems services. It preserves land abandonment and provides a livelihood for populations living such areas, conserves local traditions and cultural heritage related to cheese-making activity, enriches biodiversity of pastures consequently increasing the accessibility for tourists. Using by-products in livestock diets transforms waste into source of nutrients, feeding the virtuous cycle of circular economy. Confirming previous findings, our results show that both grass-based feeding and use of by-products are effective feeding strategies to make dairy systems more sustainable, considerably reducing the feed-food competition as well as providing ecosystem services with relevant ethical and socio-cultural advantages.