Answer: I am pleased to provide you with information on uses of excess whey from cheese production.
Whey is a byproduct of cheese production and contains mainly lactose, minerals, and water (6-7% total solids). Approximately nine pounds of whey are produced and a gallon and a half of water is used for every pound of cheese produced. In some regions a market has been developed for the whey, but most producers find the whey to be a liability, with costs associated with shipping for land application as much as $30 to $40 per ton. There are some alternatives, and they all require the development of some new type of farm infrastructure. This letter will describe some work that has been done looking at whey as a cattle feed, a pasture fertilizer, and as a biogas feedstock.
Feeding Liquid Whey to Cattle
Direct feeding of liquid whey: Liquid whey can be fed to cattle much the same way water is delivered to cattle in dairy stall barns. A closed, gravity fed system would work well as it combines a simple, low-input system with the benefits of fly control. Whey has a low pH (around 3 or 4) and this helps to prevent spoilage as well.
Cattle drink liquid whey much the same as any liquid feed supplement, but will consume as much as 80 to 100 pounds of free-choice whey per head per day. It is important to substitute whey for other concentrates because large consumption of whey can reduce forage intake. Always change cattle rations slowly, as bloat or acidosis may result. Although a liquid, whey is nutrient dense and will not replace water in the diet. Provide clean, free-choice water at all times (Shaver, no date).
Whey silage: Another feeding method mix whey with chopped low quality forage in a feed mixer to make whey silage for cattle. After about a month the silage is completely fermented and stable, as long as it remains covered and protected. Whey silage has a dry matter of 30 to 40%, and crude protein (CP) of around 11 to 13% (ZoBell and Burrell, 2002). The energy content is usually 98% of the energy value of ear corn.
Application to Pasture as a Fertilizer
See New Zealand Journal of Dairy Science and Technology article, "Utilization of Whey as a Fertilizer Replacement for Dairy Pasture." Of particular interest is Table 1, which contains a chemical analysis of three kinds of whey: lactic casein, suphuric casein, and cheese; and Table 2, which lists the approximate amount of plant available nutrients in kilograms per hectare contained in the recommended application rate of 40,000 liters/ha [4278 gallons per acre]. The New Zealand authors concluded that whey can replace conventional fertilizers in dairy pastures, and provide suggestions for application equipment and storage pits.
Biogas from Anaerobic Digestion
Organic matter can be decomposed by bacteria in an oxygen-free environment, yielding methane that can be used as an energy source. Just about any organic substance will do, but some feedstocks are more efficient at yielding methane than others. It so happens that whey is an excellent feedstock for producing methane, and has some potential for contributing to the energy needs on the farm.
According to the European Anaerobic Digestion Network (2005), “the digestion process takes place in a warmed, sealed airless container (the digester) which creates the ideal conditions for the bacteria to ferment the organic material in oxygen-free conditions. The digestion tank needs to be warmed and mixed thoroughly to create the ideal conditions for the bacteria to convert organic matter into biogas (a mixture of carbon dioxide, methane and small amounts of other gases).
“There are two types of AD processes:
Mesophilic digestion: The digester is heated to 30 – 35 degrees C [86 – 95 degrees F] and the feedstock remains in the digester typically for 15-30 days. Mesophilic digestion tends to be more robust and tolerant than the thermophilic process, but gas production is less, larger digestion tanks are required and sanitization, if required, is a separate process stage.
Thermophilic digestion: The digester is heated to 55 degrees C [131 degrees F] and the residence time is typically 12-14 days. Thermophilic digestion systems offer higher methane production, faster throughput, better pathogen and virus ‘kill’, but require more expensive technology, greater energy input and a higher degree of operation and monitoring.
“During this process 30-60% of the digestible solids are converted into biogas. This gas must be burned, and can be used to generate heat or electricity of both. It can be burned in a conventional gas boiler and used as heat for nearby buildings including farmhouses, and to heat the digester. It can be used to power associated machinery or vehicles. Alternatively, it can be burned in a gas engine to generate electricity. If generating electricity, it is usual to use a more efficient combined heat and power (CHP) system, where heat can be removed in the first instance to maintain the digester temperature, and any surplus energy can be used for other purposes. A larger scale CHP plant can supply larger housing or industrial developments, or supply electricity to the grid.
“As fresh feedstock is added to the system, digestate is pumped from the digester to a storage tank. Biogas continues to be produced in the storage tank; collection and combustion may be an economic and safety requirement. The residual digestate can be stored and then applied to the land at an appropriate time without further treatment, or it can be separated to produce fiber and liquor. The fiber can be used as a soil conditioner or composted prior to use or sale. The liquor contains a range of nutrients and can be used as a liquid fertilizer which can be sold or used on-site as part of a crop nutrient management plan.
“AD products can, therefore, help farmers reduce their requirement for non-renewable forms of energy such as fossil fuels, and the digestate, if correctly used, can reduce demand for synthetic fertilizers and other soil conditioners which may be manufactured using less sustainable methods” (The European Anaerobic Digestion Network, 2005).
Amaral-Phillips, Donna M., and R.. W. Hemken. 1997. Using Byproducts to Feed Dairy Cattle. University of Kentucky Cooperative Extension.
Balsam, John and Dave Ryan. 2006. Anaerobic Digestion of Animal Wastes: Factors to Consider. Butte, MT: ATTRA, the National Sustainable Agriculture Information Service.
European Anaerobic Digestion Network, The. 2005. AD Basics; How Does it Work.
McGinnis, Laura. 2007. New Uses for Dairy Byproducts. Agricultural Research, May/June.
MDA. 2005. Opportunities, Constraints, and Research Needs for Co-digestion of Alternative Waste Streams with Livestock Manure in Minnesota. Minnesota Department of Agriculture, Agricultural Resources Management and Development Division.
Radford, J.B., D.B. Galpin, and M.F. Parkin. 1986. Utilization of whey as a fertilizer replacement for dairy pasture. New Zealand Journal of Dairy Science and Technology. Vol. 21. p. 65-72.
Shaver, Randy D. No date. By-Product Feedstuffs in Dairy Cattle Diets in the Upper Midwest. College of Agricultural and Life Sciences, University of Wisconsin -Madison
ZoBell, D.R., and W. C. Burrell. 2002. Producing Whey Silage for Growing and Finishing Cattle. Utah State University Extension.
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