Expanding organic pig feeding options

A closer look at using organic food processing by-products for organic pork production

By Laura Sayre

January 27, 2005: High organic feed costs have led organic livestock producers in many parts of the world to investigate alternative feeding strategies. Among these strategies, especially for those rearing organic pigs, is to source feed components from organic food processors. As the number and variety of processed organic food products continues to grow, so too does the quantity of organic food by-products. Use of these materials as organic feed, however, seems to be limited by a lack of knowledge of the feed value of various by-products, lack of communication between processors and farmers, and transportation and organizational constraints.

New research from Sonja Wlcek and Werner Zollitsch at the University of Natural Resources and Applied Life Sciences in Vienna, Austria (and funded by the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management and by Bio Ernte Austria) examines the quantity and quality of food processing by-products for feeding to organic pigs. Although this research was focused on Austria, Wlcek and Zollitsch's findings should be relevant to organic pigs farmers in the United States and elsewhere.

The researchers began by sending questionnaires to 321 Austrian organic food processors, including bakeries, breweries, grain mills, and fruit and vegetable processors. Questions centered on the types and amounts of products generated, storage and handling methods, and perceived market values. Seventy-eight organic pig farmers were also surveyed concerning their current feeding practices and interest in using by-products.

The processor survey turned up a wide range of potentially useable organic by-products, from pumpkin seed cake and buttermilk to brewers' yeast and okara (a by-product of tofu production). Samples of all identified by-products were then analyzed for a range of nutritional factors, including dry matter, crude protein, crude fiber, metabolizable energy and lysine.

Next, Wlcek and Zollitsch sought to compare the potential supply of organic by-products to the total nutrient needs of Austria's organic pig population, estimated at 25,500 growing-fattening pigs and 3200 breeding sows in 1999. (Little work has been done thus far, the authors note, on the nutrient requirements of organic pigs as opposed to conventional pigs; therefore, conventional performance data--based on a farrowing interval of 171 days and 19 weaned pigs/year--were used.)

Not surprisingly, the available organic by-products varied significantly in nutritive value for pigs--high-fiber products like bran from small grains and sunflower oilcake, for instance, are better fed to ruminants, the authors note. Nevertheless, Wlcek and Zollitsch found that 42 percent of the crude protein, 31 percent of the lysine and 37 percent of the metabolizable energy needs of the 1999 Austrian pig population could theoretically be met by using available organic by-products.

The researchers identified stale bread (509 metric tons/year), feed-grade potatoes (11,100 t/yr), and whey (12,900 t/yr) as the three primary underutilized sources of organic pig feed in Austria. (Stale bread tested out at 66.3 percent dry matter with 16.17 Megajoules metabolizable energy per kilogram of dry matter (MJ ME/kg DM). Crude protein was 11.2 percent of DM and lysine was .33 percent of DM. Feed-grade potatoes were 18.4 percent DM, with 13.36 MJ ME/kg DM, crude protein 12.2 percent of DM and lysine .44 percent DM. Whey was 5 percent DM, 14.06 MJ ME/kg DM, crude protein 13.7 percent of DM and lysine 2.89 percent DM.)

Challenges to using stale bread as an organic feed source include limited shelf-life and the dispersed locations of bakeries. Potatoes are more nutritious if cooked, but cooking requires additional labor and energy. Large amounts of organic whey go unused in Austria because organic pig farmers have yet to get established in the areas where most large-scale organic milk processing plants are located. The researchers calculated that as many as 14,000 organic feeder pigs could be fed with organic whey in their country.

In conclusion, despite the range and volume of available materials, Wlcek and Zollitsch noted a deficiency in high-value protein feed materials among organic by-products. They therefore recommend increased efforts to include additional legumes--such as lupins, lathyrus, or fava beans--in organic crop rotations.

Citation: Sonja Wlcek and Werner Zollitsch, "Sustainable pig nutrition in organic farming: By-products from food processing as a feed resource." Renewable Agriculture and Food Systems 19(3): 159-67.

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