Biofuel co-products as livestock feed - Opportunities and challenges

Impact of United States biofuels co-products on the feed industry 53two nutrients of greatest concern in fish farm effluentwater are nitrogen and phosphorus. Soybean meal andDDGS are relatively high in protein, but much lowerin phosphorus than fishmeal. As a result, substitutingDDGS and soybean meal for fishmeal in aquaculture dietsreduces the total phosphorus level in the diet and lowersthe level of phosphorus in fish farm discharge water.There have been a considerable number of researchstudies conducted on the effects of feeding various levelsof DDGS to different species of fish, but, unfortunately,DDGS use in aquaculture feeds has been limited. Basedupon the following research studies, maximum dietaryinclusion of DDGS in aquaculture diets are shown inTable 9.• Channel catfish (Ictalurus punctatus) – Wilson and Poe,1985; Shiau, Chuang and Sun, 1987; Jauncey and Ross,1982; Robinson, 1991; Tidwell, Webster and Yancey,1990; Webster, Tidwell and Yancey, 1991; Webster etal., 1993; Robinson and Li, 2008; Lim, Yildirim-Aksoyand Klesius, 2009.• Rainbow trout (Oncorhynchus mykiss) – Cheng andHardy, 2004a, b; Cheng, Hardy and Blair, 2003; Stoneet al., 2005.• Freshwater prawns (Macrobrachium rosenbergii) –Tidwell et al., 1993a, b; Coyle, Najeeullah and Tidwell,1996.• Pacific white shrimp (Litopenaeus vannamei) – Lim,Yildirim-Aksoy and Klesius, 2009.• Tilapia (Oreochromis niloticus) – Wu et al., 1994; Wu,Rosati and Brown, 1996, 1997; Tidwell et al., 2000; Limet al., 2007.• Sunshine bass (Morone chrysops × M. saxatilis) –Thompson et al., 2008.TABLE 9Current, revised recommendations for maximum dietaryinclusion rates of DDGS for various species of fishSpecies % DDGS CommentsCatfish Up to 30%Trout Up to 15% Without synthetic lysine andmethionine supplementationTrout Up to 22.5% With synthetic lysine andmethionine supplementationSalmon Up to 10%FreshwaterprawnsUp to 40%Can replace some or all of thefishmeal in the dietShrimp Up to 10% Can replace an equivalent amountof fishmealTilapia Up to 20% Without synthetic lysine andsupplementation in high proteindiets (40% CP)Tilapia Up to 82% With synthetic lysine andtryptophan supplementation in lowprotein diets (28% CP)Horses, rabbits and companion animalsThere are significant opportunities to increase the use ofDG co-products in non-traditional markets for use in horse,rabbit and companion animal feeds. Based upon the limitedresearch information available, it appears DDGS is avery suitable ingredient for use in horse (Bonoma et al.,2008; Hill, 2002; Leonard, Baker and Willard, 1975; Ormeet al., 1997; Pagan, 1991), rabbit (Villamide, de Blas andCarabano, 1989) and dog (Allen et al., 1981; Corbin, 1984)diets. However, very little DDGS has been used in diets forcompanion animals, primarily due to current perceptionsabout the risk of mycotoxin contamination.Human foodsOne potentially large, undeveloped market for distillersco-products is the human food and neutraceutical market.DG is suitable for human consumption provided that themaize used to produce ethanol and DG is food grade andthe production facility is approved for food production.Components in DG that are a potential concern for usein human foods include: amount of yeast cells (nucleicacids), bacteria, low lysine relative to protein levels, metalcontamination and antibiotic residues. However, considerableresearch must be conducted to determine appropriatehuman food applications for DG.DG has many nutritional components that give it potentialfor use as a functional food in human nutrition, and italso has nutraceutical properties (Plate and Gallaher, 2005).Unfortunately, there is limited information on the effectsof distillers co-product consumption on human health.Some of the important nutritional components found inmaize distillers co-products include unsaturated fatty acids;antioxidants and phenolic acids; beta glucans; fibre; andxanthophylls.Several components of maize (i.e. arabinoxylans, phytosterolsand xanthophylls) have been shown to be effectivein lowering cholesterol, which may have benefits forreducing cardiovascular disease in humans. Maize and itsco-products are higher in natural antioxidants (e.g. ferulicacid) than other grains, and these antioxidants have beenshown to be effective in reducing colon cancer and controllingtype 1 diabetes. Maize distillers co-products are highin carotenoid pigments called xanthophylls. Two of thesepigments, lutein and zeaxanthin, are uniquely concentratedin the macular region of the retina and are associated withpreventing macular degeneration, several types of cancer,and coronary artery disease.Research is being conducted to evaluate therapeuticuses for maize-based distiller’s co-products, thereby increasingthe value of these co-products. The value of distiller’sco-products will be increased if it can be demonstrated thatthey have functional food or nutraceutical properties beneficialfor human health, rather than being strictly used as