A review on the use of agro-industrial CO-products in animals’ diets

The use of agro-industrial co-products in animal nutrition could represent an opportunity to reduce the environmental impact of the food production chain. Co-products can decrease the feeding cost and improve animal products in terms of quality and sustainability. To evaluate the use of co-products as animal feed, 57 studies published in the last 11 years on agro-industrial residues were considered. In vitro trials demonstrated that some co-products, such as ginseng meal, grape pomace and olive cake, in animal diets could affect fermentation parameters decreasing the gas production, particularly the methane emission. Indeed, thanks to their chemical composition and the presence of some bioactive compounds, such as tannins, these co-products seemed able to modify the ruminal and the intestinal environment and consequently fermentation kinetics and end-product. Furthermore, fruits, vegetables and oil extraction co-products could be valid sources of energy, fibre and protein, respectively. The remaining studies, conducted in vivo on different animal species, evidenced as some fruits and oil extraction co-products (e.g., prickly pears, olive, and hemp cake) could improve milk and/or meat fatty acid profile. Moreover, the antioxidant compounds of these co-products could have beneficial effects on gut microbiota and animal health status. The replacement of traditional feedstuffs with agricultural or industrial co-products could represent an interesting prospect for animal production. However, it is important to individuate the right dosage of supplementation in the animal diet, considering that all fruit and vegetable residues showed high variability in chemical composition.Highlights Reduce animal production environmental impact Increase animal welfare Reduce nutritional costs