Sponsoring Institution
National Institute of Food and Agriculture
Project Status
Funding Source
Reporting Frequency
Accession No.
Grant No.
Project No.
Proposal No.
Multistate No.
Program Code
Project Start Date
Aug 1, 2018
Project End Date
Mar 31, 2019
Grant Year
Project Director
Ashburn, B.
Recipient Organization
Performing Department
Non Technical Summary
The growing craft brewing industry produces significant amounts of spent yeast, trub (grain proteins) and spent hops that are presently treated as waste. Their disposal can be a headache for the brewer and municipal waste treatment authorities. We have created a combination of these materials called THYM (Trub Hops Yeast Mix) and are developing it into an agricultural feed supplement for cattle. Based on our earlier work with spent craft yeast and anti-microbial hop acids, we expect THYM to improve livestock growth and reduce their production of methane. THYM should improve the digestive response and growth of cattle by altering the metabolism of their gut (rumen) microbes in a manner similar to conventional antibiotics. Commercialization of THYM as a feed supplement faces three major hurdles: a high moisture content-which make it difficult to transport and manipulate, an untested growth potential as a supplement, and a limited understanding of how it affects the cow's digestive response/very important rumen microbes. To address these problems, we will 1) evaluate several industrial methods for drying THYM suitable for a midsize craft brewery, 2) run a 2-month growth and metabolism study in Angus steers and 3) further investigate the natural products in THYM and their effects in the rumen. This ground work will help turn craft brewery byproducts into a commercial feed supplement that improves growth, reduces antibiotic use and lowers greenhouse gas emissions.
Animal Health Component
Research Effort Categories

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
Goals / Objectives
Project Goal:Craft Brewery side streams include significant amounts of spent yeast, precipitated grain proteins (trub) and spent hops. Disposal of these side streams is expensive, wasteful, not environmentally friendly, and burdens local municipal wastewater treatment plants. The GOAL of this proposal is to develop a patented process to manufacture an animal feed supplement - THYM (Trub, Hops, Yeast Mix) - with significant economic and agricultural value by repurposing co-products from craft breweries that are presently treated as waste. This mixture provides a valuable protein source, has natural antibiotic properties, reduces methane production in cattle, and can improve the rate of weight gain in animals. It addresses three USDA/NIFA/SBIR FY-2018 Research Priorities for Animal Production and Protection (Program Code 8.3): 1) Increase feed efficiency, 2) Develop alternatives to the use of antibiotics, and 3) Establish a technology that decreases greenhouse gas emissions. Project Objectives:Develop infrastructure at Highland Brewing Company for harvesting THYM.Evaluate cost and labor intensity of several small-scale drying methods to reduce the moisture content to 15% or less.Measure total nutritional parameters of THYM as produced and during experimental drying steps. Evaluate THYM as a feed additive in growing cattle diets.Extend knowledge of the effects of hop- and protein- rich co-products on bovine rumen metabolism using batch anaerobic cultures with bovine rumen microbe samples obtained at slaughter. Consolidate the results of experimentation noted above to develop a final process and product that can be sold or franchised around the world anywhere there are concentrations of breweries.
Project Methods
MethodsEfforts will be concentrated by the separate entities with the goal of developing enough data and knowledge to change the way that THYM is looked at by breweries, cattle producers, municipalities, and institutions of higher learning. Students at both NCSU and Warren Wilson College will be involved with data collection. The following breakdown shows the general arrangements.Develop the mechanical infrastructure at Highland Brewing Company for harvesting THYM. Address the question: Can this equipment be installed at a cost that will not deter other breweries from side streaming this important co-product?Realignment of stainless piping to properly locate pumps that will effectively move the yeast/hop slurry to the mixing tanks.New stainless piping to effectively collect hot trub from the whirlpool and move it to the mixing tanks.Additional glycol lines to temperature control the liquids and solids.Potential new steam line to storage tank to test ability of THYM to withstand high temperatures during storing or killing yeast.Dewatering filter bags: The "wet" THYM will be pumped to various porosity bags to gauge dewatering effectiveness. This will allow for the material to be moved around by shovel, skid steer, or other machines.Addition of organic acids to yeast/hop slurry to inactivate live yeast.Samples of 5, 50 and 500 lb will be stored 4, 21 and 38 ºC and tested for hop acid content, yeast viability and microbial (aerobic) contamination.Lab testing of all waste stream before, during, and after mixing to track the growth of natural yeast and bacteria. Correlate the effects of the time and temperature on the mixed product, thus allowing for variations in product and predictions of its overall effectiveness.At Highland Brewing Company evaluate cost, labor intensity and effectiveness of several small-scale drying methods to reduce the moisture content of THYM. Address the questions: Can this be done on a non-industrial, moderate scale? Can enough water be removed to keep material handling and transportation costs down?Test one or all of the following: belt press/filter press/centrifuge dewatering systems - These systems are designed to dewater to 15% moisture content. At this moisture content, the material can be pelletized and shelf stable.Drum drying trials by shipping THYM samples to a vendor that will evaluate the suitability of atmospheric, steam heated drum dryers for this material. Testing various drying techniques including rotary dryers, fluid bed dryers, agitated mixing dryers, flash dryers, and spray dryers.At NCSU facility, after dewatering goal is complete,the goal is to screen a new and novel brewer's byproduct feed (THYM) and assess its potential for producing high body weight gains, efficiency of feed to gain conversions, and an altered ruminal volatile fatty acid and plasma metabolite profile when compared to monensin (Rumensin®) in beef cattle diets. Address the question: Does THYM improve cattle performance and can it be used as an alternative to monensin?This study will be conducted at the NC Department of Agriculture's Mountain Research Station in Waynesville, NC, utilizing a half-covered drylot feeding facility with 45 weaned Angus steers (272 ± 11 kg). Dietary treatments will consist of 1) total mixed ration control diet (negative control), 2) total mixed ration with Rumensin® (positive control), and 3) total mixed ration with THYM (test diet). Experimental diets will primarily consist of corn silage with the addition of soybean meal and other by-product feeds, to balance protein level, and a mineral supplement to meet the animal's minimum requirements. Diets will be balanced to support a growth rate of 0.91 kg/hd/d. Rumensin® will be included in a formulated premix to offer 200 mg per head daily while THYM will be added to the total mixed rations at 2% (DM) to provide approximately 10 g per head daily of total hops bitter acids. A 14 d adaptation period will be used to acclimate steers to the pens and a silage-based diet, and will be followed by a 63 d experimental period. Sample collection:Both feed and feed refusals will be collected and analyzed for nutritive value. Steers will be weighed on two consecutive days at the beginning and end of the experimental period, and one weight will be obtained on day 21 and 42.Blood samples for analysis of blood urea nitrogen concentrations will be collected via jugular venipuncture.Ruminal fluid collected via stomach tube will be obtained two hours after the morning feeding, three times during the experiment.Response variables of average daily gain, dry matter intake, gain to feed ratio (feed efficiency), blood and ruminal metabolites will be statistically analyzed for significance.Investigators at Warren Wilson College will determine the variability in hop acid and prenylated flavonoid content between batches of THYM. They will extend our understanding of THYM potentials through batch anaerobic incubations with rumen microbes, measuring effects of THYM on ammonia, pH, short-chain fatty acid, and methane production for various substrates. Results with THYM will be compared to protein control incubations using baker's yeast and soy to normalize protein content and monensin as a positive control. Profile the hop acid and prenylated flavonoid content of THYM by HPLC analysis of extracts using UV detection and authentic standards.Conduct in vitro metabolism studies with bovine ruminal microbes obtained at slaughter from a local abattoir. Use anaerobic, batch 24 hr. incubations with substrates mimicking the feedlot studies. Compare the production of fermentation products including methane, ammonia, and acetate/propionate ratios with varying amounts of THYM supplement vs baker's yeast, soy protein and monensin controls. Examine the relationship of microbial metabolite production +/- THYM as a function of incubation time, pH and substrate composition in comparison to a standard monensin response. Evaluate potential for conversion in the rumen of xanthohumol to estrogenic 8-prenylnaringenin during microbial incubations with THYM.EffortsHighland Brewing CompanyLead the outreach to local citizens, environmental groups, and municipality to build momentum towards the potential Phase II of the project. Phase II will help create a true business model that will solve the many negative aspects of brewery waste.Representatives from Highland will join team members at conferences and presentations.NC State University/ Animal Feeding TrialScientific findings presented at national, peer reviewed conferencesResults disseminated at extension sponsored events and county cattlemen's meetingsExtension fact sheets on THYM handling and feedingWarren Wilson College in vitro bovine rumen microbial studiesInterest undergraduates in participating in these anaerobic studies Present at ACS and university-sponsored local science meetingsSubmit research findings to national microbiology or agricultural journalsConsider participating in a national rumen biology meeting in 2019Evaluation/MeasurementKey MilestonesAttain a THYM-related side stream productFind a process to reduce THYM water content to 50%Further reduce water content to 85%Supplementing feed at 2% THYM is practical and acceptable to stockMinimize loss of alpha and beta hop acids to <20% during drying Achieve steer growth enhancement with THYM over control dietsAchieve steer growth in THYM group comparable to monensin-treated groupDemonstrate that THYM improves P/A ratios and reduces methane production by rumen microbes in vitro to extent a similar to monensin.