Sustainable pig nutrition in organic farming: By-products from food processing as a feed resource

Summary

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 in 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 available of the respective by-products. 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 2,400 t of wheat bran, 990 t of rye bran, and 1,300 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 (2,000 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 (byproduct 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 to lose 18 %, 18 % and 26 % of crude protein (CP), lysine and ME , respectively, of the entire nutrient supply available from organic by-products.