Byproducts from the agro-food industries: quality feedstuffs not to be neglected

For decades, agro-food chains have been producing either first or second transformation byproducts, which represent in France a significant amount of resources (12 million tons of dry matter, Reseda 2007). These byproducts come mainly from the crushing sector (29 %), sugar refinery (14 %) and starch industry (13 %). Most of these resources (75 %) are used in animal feeding, including about 80 % via the compound feed industry and 20 % directly on the farms. Hence, agro-industrial by-products, which are clearly defined as non-waste products by French and European regulations, have become raw materials used in animal feed and must therefore comply with the regulations applicable to such products. The availability of these byproducts can vary considerably over time with a marked seasonality for certain sectors, as well as spatially according to the distribution of agro-food factories on the territory and the overlap with the animal production areas. The technological processes generating these byproducts can differ from one sector to another. Botanical and chemical composition of byproducts depend on the process implemented, which can evolve over time but also from one factory to another within the same agro-industry sector. Making the most of these byproducts in animal feeding is largely conditioned by the precise knowledge of the quality of the various organic (essentially cell walls and proteins) or mineral fractions accumulated in the byproducts, and of their utilization efficiency which can change strongly according to the animal species (ruminants vs monogastrics) and according to the types of processes applied. Some feeding recommendations and sanitary rules must be enforced to ensure an optimal utilization of byproducts by the animals without decreasing their performances. Therefore, these byproducts have a real economic value that can be determined, even for ruminants, using the low-cost linear programming formulation tools commonly used for monogastrics.