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

Abstract

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.

Challenges in the nutrition of organic pigs

“…Unlike in conventional animal production, only small amounts of easily utilisable organic industrial by‐products with a high nutritional value are available as feedstuffs for monogastric animals 24. These by‐products could serve as a supplement for legume grain‐based diets and thereby increase the value of the dietary protein.…”

“…high moisture content, short shelf life, necessity to process them before feeding, etc.). Overcoming obstacles such as the incomplete separation of organic from conventional by‐products in the processing units, the eventually necessary adaptation of processing and feeding techniques and the poor knowledge of farmers about the actual feeding value of such ‘unconventional’ feedstuffs will help to increase the amount of by‐products in the diets of organic pigs and therefore to close the nutrient cycles and improve the sustainability of organic pig production 24…”

“…If by‐products are to become a quantitatively important nutritional source for organic pigs, the range of potential feedstuffs needs to be extended to include further ‘unconventional’ diet components such as protein extracts from plants used for different purposes, etc 24…”

Peruna- ja vihannesjätteen käsittely ja käyttö maatilalla

“…Peruna-ja vihanneskuorijätteen käytöllä karjan rehuna on monia etuja. Se säästää luonnonvaroja, lisää paikallisten tuotteiden käyttöä ja ylläpitää ravinteiden kiertoa (Wlcek & Zollitsch 2004). Kuorimassan arvo karjanomistajalle riippuu mm.…”

Okara as a protein supplement affects feed intake and milk composition of ewes and growth performance of lambs

“…Consumption of okara by humans is further confounded by the high fiber content of okara, which makes it much less able to be consumed in mass quantities by humans. Okara is used as animal feed ( Wlek and Zollitsch, 2004 , Sinha et al., 2013 ), but in some areas it is also burnt as fuel or even dumped in landfills ( O'Toole, 1999 ).…”