Brewery spent grains is the solid residue left after the processing of germinated and dried cereal grains (malt) for the production of beer and other malt products (malt extracts and malt vinegar). Brewery spent grains is a readily available, high volume low cost by-product of brewing and is a potentially valuable resource for industrial exploitation.
Nutritive value of brewery spent grains
Wet brewery grains is a good source of protein with protein content that ranges from 25 to 34%. Brewery spent grains are low in calcium and potassium. A well-balanced mineral supplement should be supplied when using wet brewery grains in cattle diets to avoid the negative effects of decreased growth performance experienced when this ratio is not properly balanced. Brewery spent grains from sorghum contains high levels of anti-nutrients such as tannins which are very dangerous to animals if consumed in high quantitates (over 10 kgs/day).
Techniques for brewery spent grains preservation and storage
The high moisture content of brewery spent grains (80 to 85%) makes brewery spent grains particularly susceptible to microbial growth and subsequent spoilage in a short period of time (7 to 10 days). Wet brewery grains can be preserved through: (1) silage making and; (2) dehydration/drying.
Silage is a good method for storing wet brewery spent grains for a long period, particularly since ensiling does not alter their nutritive value. Wet brewery grains silage can be done without additives or other raw material provided that the grains are put in plastic tank or tube; pit/trench silo or plastic tanks as soon as possible. The silo (pit/trench or plastic silage bags) should be protected from rain and tightly packed.
Trench/pit silo containing brewery spent grains
The silo should have proper drainage to collect runoff. Storage time can be improved by storing in a shaded or cool place, and by covering the surface with plastic or some other covering material that minimizes surface spoilage. Brewery spent grains silage is ready within 3 weeks and can be used during 6 months, and even more if a silage additive is used. Adding carbohydrates accelerates fermentation, releasing more acids and resulting in stable silage.
Brewery spent grains silage stored in airtight plastic drums
- Drying wet brewery spent grains
Preservation of wet brewery spent grains by drying method has the advantage of reducing the product volume, and decreases transport and storage costs. Conservation of brewery spent grains in a simple solar-dryer reduces the bulk of the product and does not change its chemical composition.
A simple solar dryer produced by Task Farm, Rubaga (Tel: 0773999934)
The use of brewery spent grains as animal feed
By far the most common use of brewery spent grains is as animal feed, primarily for cattle, but also for pigs, poultry, goats and fish.
(1) Beef cattle
The use of brewery spent grains as a partial replacement for maize silage in beef cattle diets can be adopted as a strategy to reduce feeding costs and also as an alternative source of polyphenols from a material that needs to be recycled.
Beef cattle feeding on brewery spent grains mixed with silage
A supplement of up to 15 kgs/head/day of wet spent grains is adequate to cover the frequent nitrogen deficiency of beef cattle grazing grass only pastures. Calves can be fed 2 to 4 kg daily.
Blending of wet brewery grains with other feedstuffs is an acceptable way to incorporate feedstuffs with other positive characteristics. Soybean hulls or other dry feedstuffs mix well with wet spent grains and reduce the amount of water in the final mix. Because of the low calcium and potassium and high phosphorus contents, an adequate mineral supplement should be offered to growing cattle consuming wet spent grains.
(2) Milking cows
Milking cows benefit from brewery spent grains when offered as a supplement (3 to 4 kg per cow) during milking time. This increases milk production by over 20 percent. The major challenge is a cow getting used to brewery spent grains and if there is a shortage, a dairy farmer faces a problem of a reduction in milk yield of over 40 percent.
Dried brewers grains are an excellent source of high quality by-pass protein and digestible fibre. Dried brewers grains have a good amino acid, mineral and B-vitamin content. This feed ingredient is known for putting “milk in the pail“. Dried brewery spent grains levels can replace up to 75% of soybean meal and can be used to feed lactating cows, since it provides improvements in digestibility, milk production efficiency, and economic return without affecting microbial efficiency. Suggested feeding levels of brewery spent grains are 30-40% of the ration for dairy cows
Small quantities of brewery spent grains can be fed with good results to sows and to pigs after reaching about 35 kg in amounts of 1-3 kg per day (depending on age). The amount that can be included in the diet depends on the age of the pig, but a maximum of 50% of the diet protein can be supplied by brewer’s grains without a reduction in growth rate and feed efficiency.
In chickens, supplementing their regular feed with 10 to 20 percent dried spent grainss has been found to be the most effective.
Chicken supplemented with brewery spent grains
- Goats and sheep
Research results have shown that small amounts of brewers’ grains (5-6% of diet dry matter) confer major benefits on growth performance and health of goats fed cassava foliage as the sole diet. The substitution of sorghum silage by brewery spent grains as roughage has shown to be a viable alternative from the productive and economic point of view for finishing of feedlot lambs.
Brewery waste (brewer’s grains) can be used to replace rice bran in fish diet under a semi-intensive culture system and its impact on the growth of catfish. Growth in terms of body weight gain has been reported to be highest when Catfish is fed on a diet containing 30 % brewery waste in the feed.
Dried brewers’ grains can be included in diet for growing rabbits up to 28% without affecting performance, carcass traits and meat quality of rabbits. The use of this feedstuff could help reduce the inclusion of soybean meal in diets for fattening rabbits, while increasing economic indexes and cutting the cost of feed.
Some important advice when feeding brewery spent grains:
- To prevent mould growth- drain the grains as quickly as possible, pack tightly, and cover well. Use a piece of black plastic and press it down on the top of the grains and then cover that as well. The more you compact the brewery spent grains and limit oxygen, the less likely it will mould.
- Including calcium bentonite adsorbent in the wet brewery spent grains diet (at 2-3%) reduces accumulation of aflatoxin caused by moulding. Aflatoxins are poisonous substances produced by certain kinds of fungi (moulds) that are found naturally all over the world; they can contaminate food crops and pose a serious health threat to humans and livestock. Large doses of aflatoxins lead to acute poisoning (aflatoxicosis) that can be life threatening, usually through damage to the liver.
- Scoop the top layer off before every feeding and smell the grains below it. It should smell like cooked cereal grains.
- A farmer should be extra careful when feeding brewery spent grains from sorghum to cattle. The sorghum contains anti‐nutritional factors like. Feeding too much sorghum brewery spent grains to livestock can be lead to death of animals.
- Clean water is extremely important for animal health. If the water is dirty, intake will be less than needed. Clean water troughs will also help limit the spread of diseases. Your water mineral balance can negatively affect the absorption of minerals by the animals. Provide mineral supplements.