Since keeping nutrient cycles intact is one of the most important goals in organic farming, the option of recycling by-products from organic food processing by feeding them to organically raised pigs was analyzed in this study. A more specific objective was to estimate the potential of this nutrient source for reducing the protein deficiency in organic pig nutrition. Sector-specific questionnaires were sent to 321 processors of organic foods in Austria. The information provided was used to estimate the total quantity of the respective by-products available. Proximate analysis, amino acid and mineral analysis were performed for different by-products. These data were combined with the available quantities of the respective by-products, resulting in the amounts of nutrients potentially recyclable for pig nutrition. Each year 2400 t of wheat bran, 990 t of rye bran and 1300 t of residues from the separation of seed grains are already fed to different kinds of livestock. Some 510 t of stale bread are currently disposed of, but could be used as a highly nutritive feedstuff for pigs, once the problem of collection is solved. Relevant amounts of other energy-rich by-products were found: currently, about 11,000 t (2000 t on a dry matter basis) of feed-grade potatoes are composted, resulting in a waste of 27,000 GJ of metabolizable energy (ME). These potatoes could be better utilized as a dietary energy source for approximately 12,300 pigs. Additionally, about 12,900 t of whey from organically produced milk are discarded, which could be used to feed roughly 14,000 pigs. High-protein by-products are scarce. Annually, 80 t and 63 t of expellers from pumpkin seed and sunflower seed, respectively, are produced from organically grown oilseeds. Only small quantities of okara (by-product of the production of tofu from soybeans) and buttermilk are available. Only 4% and 5% of the protein and lysine requirements, respectively, of the pigs currently kept on organic farms in Austria could be covered by by-products rich in protein. Excluding feed-grade potatoes means a loss of 18% crude protein (CP), 18% lysine and 26% ME of the entire nutrient supply available from organic by-products.

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