Biofuel co-products as livestock feed - Opportunities and challenges

96Biofuel co-products as livestock feed – Opportunities and challengesdiets or maize-based diets with added tallow (saturated fat)or added maize oil (unsaturated fatty acids). These datasuggest that a portion of the fatty acids are “protected” inthe rumen in WDGS and remain intact at the small intestine.Similar results were observed by Bremer et al. (2010c),where the unsaturated:saturated fatty acid ratio increasedfrom approximately 0.40–0.50 for maize, maize oil, tallowand distillers solubles, to 0.83 for WDGS. All diets in thisstudy were approximately 8.5 percent fat, except the maizecontrol (3.6 percent), and all had greater than 93 percentfatty acid digestibility. The fat in WDGS appears to be protectedfrom bio hydrogenation in the rumen, whereas fats indistillers solubles are not protected. Likewise, all fat sourcesare quite digestible.Fractionation co-products from dry millingThe evolving ethanol industry is continually striving to maximizeethanol production efficiency. Changes associatedwith this progress will provide innovative new co-productfeeds for producers to utilize that may be quite differentnutritionally when fed to cattle. One example of a newco-product feed is Dakota Bran Cake. Bran cake is a distillersco-product feed produced as primarily maize bran plusdistillers solubles produced from a pre-fractionation drymilling process. On a DM basis, bran cake contains less proteinthan WDGS and WCGF, similar NDF to both feeds, andslightly less fat content than WDGS. Bremer et al. (2007)evaluated Dakota Bran Cake in a finishing diet by comparinginclusion levels of 0, 15, 30 and 45 percent of diet DM.Results indicated improved final BW, ADG, DMI and G:Fcompared with feeding a blend of high-moisture and dryrolledmaize, suggesting this specific feed has 100–108 percentof the feeding value of maize. Buckner et al. (2007)compared dried Dakota Bran Cake with DDGS supplementationin diets for growing calves. They fed each of the twoproducts at 15 or 30 percent of the diet, which replaced a70:30 blend of brome grass hay and alfalfa haylage (DMbasis). Animal performance improved as the inclusion of theco-products increased. Dried DGS had improved performancecompared with the dried Dakota Bran Cake at bothinclusion levels. Dried Dakota Bran Cake had 84 percentthe feeding value of DDGS with growing steers. Previousresearch has shown that DDGS has about 127 percent thefeeding value of maize in forage based diets. Therefore,dried Dakota Bran Cake appears to have an energy valueequal to 103 percent of maize. Dakota Bran Cake is onlyone example of how new ethanol industry co-products willperform relative to traditional finishing rations.FUTURE RESEARCH AREASEach new co-product feed is different from the next.Therefore, each new feed needs to be analysed individuallyfor its correct feeding value. Changes to plant productiongoals and production efficiency will probably have significantimpacts on the feeding value of co-products produced.Research has shown differences in cattle performancedue to the interaction between level of DGS and type ofgrain processing. There are probably many interacting factors,including DMI, forage type and inclusion level, anddifferences between calf-feds and yearlings. These interactionsare complex and require further research to explain.The meta-analysis by Bremer et al. (2011) shows a clearperformance advantage for WDGS compared with DDGS.The underlying factors leading to this are not clear andshould be further researched in order to guide the ethanolindustry in producing high quality co-product feeds.Forage replacement values of DGS have been quite variable.Identifying this value will be helpful to producers usingDGS as a supplement for cattle on high forage diets, especiallyin times of drought when forage supplies are limited.CONCLUSIONSBoth dry and wet milling ethanol processes produce coproductfeeds that are suitable for cattle diets, both highconcentratediets and forage-based diets. These feeds areall quite different and require individual analyses to adequatelydescribe their nutritional content. There is also variationwithin feeds among plants, and even within plants.Co-products in a beef finishing diet can be added aseither a protein or energy source, or both. Inclusion ratesof less than 15 to 20 percent of the diet DM serve primarilyas a protein supplement. Distillers grains are an excellentsource of UIP, which can be recycled to the rumen as urea.Inclusion of wet, modified or dried DGS at 40 percent ofdiet DM in a finishing diet maximizes G:F. Maximum ADGand DMI were observed at lower levels. Feeding WDGSis the most beneficial in finishing diets, with 30–40 percentgreater feeding value than maize. Modified DGS has15–30 percent and DDGS has 13 percent greater feedingvalue than maize. ‘Sweet Bran’ inclusion in finishing dietsup to 40 percent of diet DM had a linear increase in G:F.Higher inclusions of DGS decrease these feeding values, butstill give comparable or better performance than a maizebasedcontrol, and may be economically advantageousbecause of decreased input costs. When feeding high levelsof DGS, increased S levels may hurt performance or resultin PEM. Incidences of PEM increase with increasing levels ofdietary S and cattle should be monitored closely if dietaryS is above 0.47 percent. Ruminally degradable S in the dietis a better indicator of H 2 S production in the rumen thantotal S in the diet.Environmental considerations are an important aspectof feeding DGS to cattle. Feeding DGS increases both Nand P in the manure which, if captured, increases the fertilizervalue of the manure. Feeding DGS to livestock alsoincreases the environmental benefit of fuel ethanol relative