Wet brewers’ grains, the abundant residues of the brewery industry, show promise as a potentially cost-effective, high-nutrient feed replacement for dairy heifers, according to new research from the New Hampshire Agricultural Experiment Station at the University of New Hampshire.
The brewery industry uses malted primarily barley to produce beer, leaving behind a protein-rich residue known as “beer waste” that is suitable for dairy cattle feeding.
“With the rising cost of energy and protein feeds, particularly corn and soybean, dairy farmers are looking for alternative feed sources.” One approach would be to use less expensive feeds, such as wet brewers grains, which appear to be feasible due to their nutritional value, availability, and low cost.
The brewery industry primarily uses malted barley to produce beer, leaving behind a protein-rich residue known as “beer waste” that can be fed to dairy cattle. Researchers discovered that incorporating these wet brewers’ grains into the diet of dairy heifers at a rate of 20% can completely replace soybean or corn-based feed while providing comparable growth performance to diets containing those concentrates. Feeding costs typically decrease, but this is not always the case in India. Previously, this waste was discarded in the garbage, but when farmers take it with them to feed animals, they sell it for 50p per kg which has since increased to 15Rs per kg. But still, it is way cheaper than maize and soyDOC-based feed. concentrate feed available in the market has no authenticity, in that scenario, such feeding regimes have good opportunities to reduce the cost of feeding.
A potential problem with beer waste is the quick development of fungus and the production of mycotoxins.
“Due to their high moisture content, ranging from 65 to 75 percent, improper grain storage frequently results in significant loss of dry matter and nutrients due to mould and yeast growth.” These produce various mycotoxins that are even harmful to cattle.” Brewer’s grains are byproducts of the brewery industry, which produces beer primarily from malted barley, leaving behind a protein-rich residue. Brewer’s grains have been used in dairy cattle feed and, with the exception of starch, have higher nutrient contents than barley. Brewer’s grains are high in methionine and lysine and a good source of NDF and RUP. The brewery industry generates massive amounts of waste, which are difficult to manage economically. Their accumulation in the environment is also an ecological concern.
- The major waste generated during beer production is brewer’s spent grain (BSG), which accounts for approximately 85% of all residues produced by the brewing industry. BSG is formed during the mashing process and removed prior to the brewing process’s boiling step. This solid byproduct of wort production is made up of barley grain husk. BSG is a heterogeneous material consisting of lignocellulosic biomass and is rich in proteins (20-30%), fibre (30–70%), lipids, vitamins, and minerals. It contains ca. 12–28% of lignin, 12–25% of cellulose, and 28% of non-cellulosic polysaccharides, mainly arabinoxylans.
- Brewer’s residual yeast is the second largest by-product from the brewing process. This slurry residue accounts for a maximum of 15% of the total by-products generated during the brewing process. The quality of barley distillery by-products depends on the malting and extraction process that the malt undergoes in the distillery. Germination: enzymes reduce starch into soluble and fermentable sugars Kilning: the germinated grain is dried and converted into malt. Mashing: the ground malt is immersed in hot water and then filtered so that soluble sugars are extracted, yielding a sugar-rich liquid (wort). The wort is cooled and distilled, which yields alcohol. A liquid by-product, the pot ale, is evaporated to produce pot ale syrup. Pot ale is a protein-rich liquid containing sugars, yeasts and trace copper.
- Several byproducts of malt whisky production are used in animal feed: The wet residues of malted barley after mashing are known as malt distillers. This wet product is either sold directly to farms from distilleries or mixed with other by-products at a later stage. Excess draff that is not consumed by livestock is ensiled during the summer, often with grass, for the following winter. Barley distillers used in the production of ethanol follow the same procedure as other grains. The ground grains are combined with water and enzymes (amylases) to create a mash in which starch hydrolysis takes place (liquefaction stage). Enzymes are added to the mash to transform starch into dextrose (saccharification stage). After saccharification, yeast is added to start the fermentation process, which produces a “alcohol” and CO2. After removing alcohol by distillation process wet grains and thin stillage are left. Wet grains may be fed to livestock directly or they can be dried to produce dried distillers grain.
- Thin stillage can be used as high-moisture feed or dehydrated to make condensed distillers solubles. Wet or dried distillers’ grain and solubles are frequently prepared by combining condensed distillers solubles and distillers grain (WDGS or DDGS). About 70-80% of fresh distillery waste is water. It is high in protein (17-23% DM), high in fibre (NDF greater than 60% DM), and has a relatively high oil content (more than 8% DM). It contains little starch and sugar. Many soluble minerals, particularly sodium, magnesium, and potassium, are extracted from the grain during mashing, resulting in a by-product that is mineral deficient and requires supplementation when used in large quantities in ruminant diets.
- Enzymes are added to the mash to transform starch into dextrose (saccharification stage) After saccharification, yeast is added to start the fermentation process, which produces a “alcohol” and CO2. After removing alcohol by distillation process wet grains and thin stillage are left.
- Wet grains may be fed to livestock directly or they can be dried to produce dried distillers grain.
- Thin stillage can be sold as high-moisture feed or it can be dehydrated to produce condensed distillers solubles. Condensed distillers solubles and distillers grain are often blended together to prepare wet or dried distillers grain and solubles (WDGS or DDGS). Fresh distillery waste contains about 70-80% water. It is rich in protein (17-23% DM), has a high fibre content (NDF of more than 60% DM) and a relatively high oil content (more than 8% DM). It is low in starch and sugars. During mashing, many soluble minerals, notably sodium, magnesium and potassium are extracted from the grain, resulting in a by-product that is mineral deficient and needs supplementation when it is used in large quantities in ruminant diets.
- The lack of homogeneity in the fermentation and distillery processes results in high variability in barley distillers composition, particularly for protein (15 to 32% DM) and fibre (NDF 38 to 79% DM). In a comparison of barley distillers produced in a pilot ethanol plant, distillers from hull-less varieties contained 35-36% protein vs. 24% for distillers from hulled varieties.
- BFW has a moderate OM digestibility of about 50-54% due to its large concentration of fibre. Its energy value is disputed, with reported ME values in the 9-12 MJ/kg (2100 to 2400kcal/kg) DM range. BFW is fed fresh to ruminants, or ensiled for later use. Because it contains only small amounts of available carbohydrates, BWF has little effect on rumen acidity and can been fed ad libitum to cattle and sheep, though higher performance can be expected when BFW is fed with an energy source such as cereals. A maximum inclusion rate of 30% in the diet DM is recommended. The addition of minerals is generally beneficial for livestock consuming draff-based diets.
