Question of the Week
Answer:. I am pleased to provide you with information on dairy energy efficiency, including housing, feed storage, and small scale methane capture.
Modernization of the following systems provides the most cost-effective means of reducing energy use on the farm, including the dairy barn itself;
• water heating and space heating systems,
• ventilation fan motors,
• milking equipment (pre-coolers, energy efficient compressors, variable speed pumps),
• electrical component cleanliness (clean contacts waste energy and pose a fire hazard),
• solar fencing,
• solar or wind generated water pumps, and
• timers on heating components (OMAFRA).
After addressing these areas of concern, you can begin to ascertain other areas that need treatment, such as manure handling.
Compost Bedding Dairy Barns are an integrated approach solving many farm problems, including the problem of manure handling. This design also utilizes the heat of aerobic fermentation to heat the barn space. Compost is spread on fields seasonally, and nutrient loss is much less than with spreading raw manure. However, the compost bedding process requires aeration twice a day and ventilation to remove moisture. Maintaining a compost bedding space requires constant attention, and sufficient equipment to aerate the pack twice daily. Compost bedding barns reduce the need to purchase and ship bedding materials such as wood shavings, which represents not only a cost savings but an energy savings as well. Endres and Janni (2008) suggest the following practices to ensure a successfully composted bedding pack:
Keys to Success with Compost Dairy Barns
• Provide at least 80 to 85 sq. feet per cow for Holsteins and similar-sized breeds and 65 sq. feet for Jerseys. Some producers provide 100 sq. feet per cow.
• Use fine, dry wood shavings or sawdust for bedding. Alternative bedding materials are being investigated.
• Aerate the pack twice daily 10 inches deep or deeper to keep it aerobic and fluffy. Biological activity helps dry the pack.
• Add bedding when it begins to stick to the cows (Have bedding supply available so you don’t end up adding fresh bedding too late).
• Enhance biological activity to generate heat to drive off moisture, and ventilate the barn well to remove the moisture.
• Use excellent cow prep at milking time.
Whether a compost bedding barn or a conventional barn with timely manure removal is more efficient depends on your own particular circumstances, such as frequency of removal, available land for disposal, pasture nutrient load (namely phosphorus), and personal preference. In addition to considering the energy and monetary cost of inputs such as bedding and time, consider the amount of tractor time needed to remove manure vs. aerating compost bedding twice daily.
To assist you in determining energy efficient practices, you can access the on-line NRCS Energy Estimator for Animal Housing at http://ahat.sc.egov.usda.gov/. This interactive tool will allow you to input your farm data and energy costs. The tool with then recommend practices to conserve energy and estimate savings based on your location.
Winter Forage Storage Options
There are many factors that go into determining which forage storage system has the least carbon footprint. Energy is used in forage production and storage to
• prepare the field,
• bale or ensile,
• and feed the forage.
Ineffiencies in any of these tasks can increase the carbon footprint of the evolution.
Factors that influence energy use in harvested and stored forage systems
• Harvest management – produce high quality forage by harvesting at proper stage of maturity. Efficient harvest management can ensure that the highest amount of solar capture through photosynthesis actually makes it to the feed bunk.
• Minimize storage losses – nutrients in stored hay can be preserved with proper storage, reducing the energy costs associated with supplemental feeding
• Scale-appropriate forage handling system – choose the type of system (hay bales, silage, and baleage) appropriate for your farm scale
Corn silage systems have a higher potential than hay systems to maximize energy use on a per unit basis, because the energy captured in silage is denser than in hay, although more overall energy may be used in producing silage. Grass or alfalfa silage would require less energy inputs than corn silage, due to the perennial nature of these crops. Grass or alfalfa silage does not require annual tillage, planting, or fertilization. However, the ratio of energy output per unit input is slightly lower than corn silage. High quality grass or alfalfa silage can be an excellent source of energy for lactating dairy cattle if properly produced and fed.
Round Hay Bale Storage Options
• Shed storage – longest life, least amount of dry matter loss
• Tarp on bales stacked outside – short life, low dry matter loss
• Plastic wrap with bales stacked outside – shortest life, low dry matter loss
• Stacked bales outside on rock pad – long life, intermediate dry matter loss
• Stacked bales outside – least cost, most dry matter loss
Long-cut Grass Silage – a low input method of making high quality feed
Unwilted, long-cut grass has been successfully ensiled in piles and covered with white plastic. According to Allan Nation (2005), the grass is cut and blown with equipment such as an Alpha-Ag Lacerator and blown into a wagon, then stacked on the ground and covered with plastic. The plastic is weighted along the sides with rock or soil, and the air is then vacuumed from the plastic enclosure. Silage made this way can produce high quality feed and will not spoil during feeding as long as it is fed out every day.
The New England Small Farm Institute and UC Extension has also done some research with this system and has resulted in successful deployment of this technology by many farmers in New England (Markesich, 2002). Please see these resources (listed below) for more information on making long-cut grass silage.
Methane Digesters for Small Dairies
Methane digesters can are less feasible for dairies with herds under 100 cows. The capitol investment required limits this technology to herds approaching at least 300 cows in size, although some resources suggest herds as low as 100 cows may be feasible (Barker, 2001). I have annotated several on-line resources below, including a paper from Jones, et al (1980) that includes a worksheet for determining the feasibility of methane digestion. You can download the form and enter you data to ascertain the feasibility of a methane digester for your operation.
I have also referenced a publication by Gary Baron on a small-scale digester that was constructed in the Philippines. The paper includes design details and instructions, including a link to a design chart. This small design might be feasible for small dairies and could produce enough gas to power barn lighting, domestic hot water, or cooking.
Dairying in the U.S. has traditionally produced milk on a year-round basis with a feeding system of silage, hay, and grain. However, seasonal dairying is becoming more popular. It was first practiced in New Zealand where little grain is grown and government subsidies disappeared years ago. Seasonal systems match the reproductive cycle of the cows to availability of forage. The highest nutrient requirements of the cow—during calving and lactation—are timed to occur in the season of highest forage quality and quantity, usually spring and summer.
In seasonal dairying, since all the cows dry off at once, it is not necessary to milk for a couple of months during the year. The idea is to avoid the period of highest cost milk production. In very hot, humid climates, summer might be the time to dry off the cows. In northern latitudes, this will likely be the winter months. Seasonal dairying can be a tool to increase dairy energy efficiency by maintaining dry cows during the peak energy-use months of the year.
Keys to Success for Transitioning to Seasonal Production
• Estrus synchronization
• Heat detection
• Get cows bred within narrow window of time (approx 6 weeks)
• Maintain cows on high plane of nutrition from growing pasture and high quality stored forages
• Adequate facilities for calving, calf raising, and breeding in one season
• Culling of late breeders
References and Resources:
Balsam, John. 2006. Anaerobic Digestion of Animal Wastes: Factors to Consider. Updated by Dave Ryan. Butte, MT: NCAT-ATTRA.
Barker, James C. 2001. Methane Fuel Gas from Livestock Wastes: A Summary. Biological and Agricultural Engineering, North Carolina State University, Raleigh, NC.
Composting Bedded Pack Barns for Dairy Housing. University of Minnesota Extension.
Endres, Marcia I and Kevin A. Janni. 2008. Compost Bedded Pack Barns for Dairy Cows. University of Minnesota, St. Paul.
65 Millet Street, Suite 105
Richmond, VT 05477
EnSave, Inc. is an agricultural energy efficiency consulting firm. Since 1991, EnSave has supported the American agricultural sector with innovative energy efficiency and resource conservation solutions. EnSave provides agricultural producers and food processors with cost-effective ways to reduce operating costs while saving energy and conserving our nation's natural resources by designing and implementing energy efficiency programs. EnSave also provides energy audits directly to producers. EnSave's clients include state and federal energy and environmental agencies, investor-owned utilities, and rural electric cooperatives. EnSave implements its programs by developing relationships with equipment manufacturers, local equipment dealers and the local agricultural community. Ultimately, these programs promote economic investment in the rural economy and improve the quality of America's land, air, and water.
Jones, Don D., John C. Nye, and Alvin C. Dale. 1980. Methane Generation From Livestock Waste. Department of Agricultural Engineering, Purdue University.
Includes a worksheet for determining the feasibility of methane digestion.
Markesich, Kim Colavito. 2002. Farmer research groups tackle real world issues, in Journal, vol.9 no 2. University of Connecticut College of Agriculture and Natural Resources.
Nation, Allan. 2005. Tips on how to make direct-cut vacuum silage. The Stockman Grassfarmer, November issue.
NRCS Energy Estimator: Animal Housing. http://ahat.sc.egov.usda.gov/
Ontario Ministry of Agriculture, Food, and Rural Affairs (OMAFRA). Options to Reduce Energy use on the Farm.
University of Wisconsin Extension Forage Resources. Silage Harvesting & Equipment.
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