Biofuel co-products as livestock feed - Opportunities and challenges

Utilization of co-products of the biofuel industry as livestock feeds – a synthesis 511northern Australia. The integration of trees into pasture landhas many potential benefits for sheep and cattle (Braid, 25).In India, four strategies were proposed to overcome theshortage of protein for livestock: (1) restricting exports ofoilseed meals; (2) increasing areas of cultivation for growinghigh quality green forage crops; (3) increasing efficiencyof use of existing protein feeds; and (4) identifying nonconventionaloilseeds and, if necessary, taking measures todetoxify the resulting seed cake (Dutta, Panda and Kamra,22). This last approach matches the Indian government’spolicy of increasing production of biodiesel without aggravatingthe conflict of interest between biofuel and foodproduction, and resulted in identification of karanj andneem. In the past, the karanj plant (Pongamia glabra) hashad many uses, including as a traditional medicine, withthe oil supplying heat and light (Dutta, Panda and Kamra,22: Table 1). However, extraction of the oil results in a seedcake that at present is often used as fertilizer, but whichneeds detoxifying before feeding to livestock (Dutta, Pandaand Kamra, 22). Abbeddou and Makkar (19) discuss nineoleaginous crops suitable for oil extraction but that leavebehind toxic co-products, which after detoxification couldbe used as protein feeds. The authors stress that detoxificationtechniques need to be suitable for up-scaling ifsufficient material is to be handled to have an impact inthe market. Makkar, Kumar and Becker (21) outline thepotential for Jatropha spp., a hardy shrubby tree that growsin wild or semi-cultivated areas, often on degenerated landin Africa, Asia, and Central and Southern America. Its seedscontain 55–60 percent oil that yields good quality biodieseland the residue is rich (60–66 percent) in CP (Makkar,Kumar and Becker, 21).With the increased use of algae for oil production,research into technical aspects of using these sources isneeded. Currently there is no commercial activity withalgae, but as an industry suited to development in coastalregions of the world, it could be developed in Australia,with the co-products being used for energy generation orpossibly in livestock nutrition (Braid, 25).Biodiesel co-productsCrude glycerine is an important co-product from thebiodiesel industry (Table 3). Its purity is measured by theamount of water it contains. Pure glycerol has less than5 percent water and is also colourless. Crude glycerol containsincreasing amounts of water and other impurities thataffect the colour, with increasing shades of brown as thewater and impurities increase (Shurson et al., 10; Drouillard,8; Cooper and Weber, 1). In the USA in 2010, 48 percentof glycerol was sold for high value uses, while 33 percentwent to the livestock feed industry (Cooper and Weber, 1).Glycerine at different purities may help to stabilize thehygienic quality of pelleted feeds without affecting thephysical quality of the pellets. Mature cattle can consume1 kg of glycerine per day, as a source of rapidly fermentablecarbohydrate, while it is not clear if the sweet taste of thisproduct acts as an intake stimulator (Hippenstiel et al., 11).Drouillard (8) estimates that the yield of glycerine is approximately10 percent of that of the oil or fat from which it isderived, with pure glycerine being used in human food andindustrial processes including; beverages (glycerine contains60 percent of the sweetness of sugar); pharmaceuticals;synthetic polymers; cosmetics and personal care products;and, after modification, as an emulsifying agent. Glycerinealso has humectant properties beneficial in both food andfeed production systems, in the latter for texturing propertiesand dust control, although reduced production costsof pellets and improved hygiene have also been noted(Drouillard, 8).Camelina meal contains 36–40 percent crude protein,11–12 percent fat and 4600 kcal/kg gross energy. Its proteinis rich in essential AA, including lysine and methionine.The fat is rich in alpha-linolenic acid, the parent fatty acid ofomega-3, and the antioxidant tocopherol, both necessaryfor healthy, productive poultry and quality poultry productsfor humans (Cherian, 17).Castor cake is a high-protein product, but its use aslivestock feed is restricted because of toxins, especially ricin,which means that a large proportion of the residue cakeproduced is used as organic fertilizer. However, treatmentsinvolving heat, water and alkali, especially the use of NaOH,have reduced the problem (Anandan, Gowda and Sampath,20; see also Table 6 of Chapter 20 for a summary). If marketedat the current (2011) price, plus the cost of treatment,it would still be competitive with other protein feeds.The authors suggest that the use of castor cake, through itspromotion and marketing, should be handled by a unitedapproach involving all interested parties. All the major castorproducing countries, namely India, China and Brazil,also have large numbers of livestock and therefore a largedemand for protein feeds, to which detoxified castor cakecould make a significant contribution (Anandan, Gowdaand Sampath, 20).Pongamia cake (karanj) is available in two forms,from either a mechanical-extraction process or a solventextractionprocess, but both contain anti-nutritional factors(Braid, 25). The use of karanj cake, both expeller andsolvent extracted, is limited by the presence of three typesof toxins: furanoflavones, tannins and trypsin inhibitors(Dutta, Panda and Kamra, 22). The AA profile of Karanjcompares favourably with traditional proteins, and it containsmore Ca, P and Na than soybean meal, but less Cuand Fe (Dutta, Panda and Kamra, 22).Neem oil has traditionally been used for soaps, creams,toothpaste, etc., with the cake, which contains 35–49 percentCP, used as fertilizer or as a pesticide (Dutta, Panda