Co-products from biofuel production for farm animals – an EU perspective

The first part of this chapter presents a brief history of co-products from bio-ethanol production. Co-products, such as distillers grain, are well known for their beneficial nutrient composition and have been used in animal nutrition since the early 1900s. Recent animal trials have shown that wheat-based dried distillers grain with solubles (DDGS) can replace protein supplements like soybean or rapeseed meals in dairy cow diets up to about 200g/kg dry matter (DM). In contrast to maize-based DDGS in North America, which is higher in fat, European wheat-based DDGS has not influenced milk fat content negatively. Moreover, trials with fattening bulls showed that DDGS as a main protein source is able to sustain high productive performance. Trials with grower-finisher pigs suggested that DDGS up to 200g/kg diet did not influence growth performance, fattening and slaughtering variables. similarly, laying intensity of hens as well as egg quality and health were not affected by inclusion levels ranging from 150g/kg to 300g/kg diet. Trials with broilers suggest that diets that contain more than 100g/kg DDGS may reduce performance. Hence, it is recommended to add non-starch polysaccharide (NSP)-degrading enzymes (e.g. xylanase or xylanase mixed with other enzymes) to poultry diets rich in DDGS. In the second part, a brief review and summary of data is presented on the use of glycerol for farm animals, with emphasis on ruminants, which will cover quality criteria for glycerol, rumen events and effects on feed intake and performance of dairy cows. As a fail-safe usage for glycerol in diets of all farm animals, methanol should be removed from the glycerol as far as technically possible. Glycerol at different purities may help to stabilize the hygienic quality of pelleted compound feeds without compromising pellet physical quality. Glycerol is a versatile feedingstuff, in particular for ruminants. Data on ruminal turnover of glycerol would suggest that it could replace rapidly fermentable carbohydrates and thus is not a direct competitor of propylene glycol. Previous studies have shown that glycerine may help to prevent ketoacidosis in high yielding dairy cows by increasing glucose precursors. Mature cattle can consume considerable quantities of glycerol (1kg/day). However, greater dry matter intakes by cows supplemented with glycerine often did not result in increased milk or milk component yields. Further effort is thus required to fully explore the potential of glycerol in dairy cow diets, but type of diet and route of glycerol administration seem to play important roles. In the third part, again putting an emphasis on ruminants, the feeding value of rapeseed products such as rapeseed meal (solvent-extracted) and rapeseed cake (mechanically extracted) is reviewed. Rapeseed meal compares well with soybean meal for dairy cows if fed on an isonitrogenous basis. Milk and milk component yields were similar for diets containing soybean meal or rapeseed meal. The value of rapeseed cake would benefit from standardization of the composition, because varying crude fat and crude protein concentrations makes the feeding value difficult to predict and could also affect storage stability of the cake. Even though the amino acid composition in rapeseed products is quite well balanced and favourable to non-ruminant animals, the sensitive reaction of pigs and poultry to glucosinolates in rapeseed meal and cake are still of concern. Therefore, it is recommended to add iodine, since glucosinolates act as antagonists. However, if glucosinolates are present in high concentrations, the negative effects may not be compensated, even if iodine is supplemented at high levels. Concluding, it is evident that a more widespread use of rapeseed meal and rapeseed cake in diets for pigs and poultry requires further reduction of glucosinolate levels. Finally, energy utilization efficiency and sustainability of co-products from biofuel are addressed. To date, no definite regulations exist in order to assign emissions either to the main product or the co-product(s). Applying a causation principle, the producer or the responsible party should be accountable for all emissions. However, drying of DGS is only of interest if the products will be utilized as feedstuffs for animals, and thus emissions associated with processing of co-products are not of interest or necessity for biofuel producing companies.