Strategies for Energy Use on the Dairy Farm
by David B. Fischer
TAKE HOME MESSAGES
- Supplemental lighting with energy efficient lamps can increase milk production 5 to 16 percent.
- Relieving heat stress with a combination of sprinklers and fans can increase the cooling effect and improve energy use.
- Well planned manure nutrient management plans will reduce the use of commercial fertilizer and energy costs associated with the manufacturing.
Monitoring energy cost and usage on the dairy farm often takes a back seat to the many other expenditures involved in producing milk. Usually it is feed, labor, and capital investment related costs that concern producers the most. This is understandable because these costs account for 75 to 80 percent of the total cost to produce milk. However, energy usage also deserves close attention as the dairy producer attempts to produce the most amount of milk for the least cost possible. There are some things that dairy producers can do to reduce energy usage and/or improve milk production through adopting practices that will yield increased net returns. This paper will focus on three management practices relating to energy conservation and use of energy for maximizing profits.
SUPPLEMENTAL LIGHTING IMPROVES MILK PRODUCTION
Increasing the number of hours that lactating cows are exposed to light can increase milk production by 5 to 16 percent. This data is derived from a summary of eight research studies conducted to determine the response of lactating cows to supplemental lighting. The research concluded that cows exposed to a longer photoperiod can achieve an average milk production increase of 8 to 10 percent when compared to cows receiving no additional daily supplemental light. Depending on the geographical location and time of year, normal daylight hours will vary from 9 to 14 hours. This is significantly less than the 16 to 18 hour block of light suggested for stimulating increased milk production. Keep in mind that the response to the extra lighting triggers a hormonal effect caused by the cow's body perceiving the extra light. In order to create the photoperiod necessary to stimulate the increase in milk production, three criteria need to be met:
- provide 16 to 18 hours of continuous light
- provide 10 to 20 foot candles of illumination from the supplemental lighting
- provide a 6 to 8 hour block of darkness
Increased milk yields have been observed using a variety of lighting fixtures. Some energy savings can be obtained by selecting the right type of lights. When replacing old fixtures or building new facilities, consider replacing the standard incandescent light bulb with fluorescent or high-intensity-discharge (HID) lights. These energy efficient lights are designed to be left on for longer periods. Fluorescent lights are recommended for stanchion/tie stall barns where the mounting height is usually 8 to 9 feet and are located in warm buildings. Since fluorescent lamps are hard to start in cold conditions and the light effect decreases greatly when mounted over 10 feet high, the use of HID lamps are suggested for freestall barns and outside feedlots.
The mounting height of these HID lamps should be 12 to 16 feet above the floor depending on the size (wattage) used. The HID lamps recommended include high-pressure sodium and metal halide. These lights may require 5 to 10 minutes to start but are a good choice for saving energy while providing large amounts of illumination. It is suggested to install a timer on the lighting system to maintain a uniform on and off schedule and reduce the human element of forgetfulness. In addition, the timers are set to turn lights off during daylight hours thereby reducing energy usage.
The response to the extra lighting is a hormonal response triggered by the cows body perceiving the extra light. Providing the proper light intensity, which hits the cow's eye, is important to create the hormonal response effect. Recent research indicate that long days increase the insulin-like growth factor-1 (IGF-1) which influences milk production. Responses from the supplemental light has been seen at 10 to 12 foot candles, however it is recommended to provide up to 20 foot candles of light. Foot candle is a measurement of the quantity of light that hits a designated area (i.e. a 60 watt incandescent light bulb placed 6 feet above the surface will provide about 20 foot candles). Lamps are rated by lumens and a foot candle equals 1 lumen per square foot. The goal is to have 20 lumens per square foot of target area. The type of building and mounting height will be a factor in how much of the light is diffused before it hits the target area. Precise measurements can be made with a light meter that measures foot candles.
Incorporating supplemental lighting for the feeding area should be the first priority. This not only encourages the cows to eat additional feed during the evening hours, but it also provides the continuous lighting effect while the cows are at the bunk. This is especially important when the feeding area is separate from the housing area. After determining the layout of fixtures over the feed bunk, place additional fixtures over the stalls to provide the required illumination to all parts of the housing area. Spacing requirements of the light fixtures will depend on lamp size, desired foot candle of light and indoor versus outdoor lighting conditions. Specific lighting recommendations are available from manufacturers and lighting specialists.
Based on the research, it is critical to provide 6 to 8 hours of darkness each day in order to get the full effect of the added light. Lactation studies, completed at the University of Maryland, comparing 24 hours of continuous lighting versus 16 hours light - 8 hours dark, showed no additional milk yield for the 24 hour lighted period. This is important to note as a means of reducing electrical usage and costs by merely turning the lights off for 8 hours during the night. As mentioned earlier, the use of timers is recommended to shut down the lights at night and restart in time for the pre-dawn chores the next morning and turn off again once adequate natural day light occurs. Incandescent low wattage lighting can be maintained throughout the dark hours in order to provide some visibility for cow movement.
What is the bottom line? Based on the research, the potential increased milk production minus the daily electrical use and increased feed cost would yield a net profit of 35 to 40 cents per cow per day. Assuming a total installation cost of $25 to $50 per cow (new vs. remodeled), the payback period would be 71 to 142 days. It is important to note that the increased milk production efficiency will vary from farm to farm based on the total management level. However, the addition of supplemental lighting is a management tool that both small and large herds can benefit.
FANS AND SPRINKLERS REDUCE HEAT STRESS
Hot weather, decreased milk production and increased energy bills continue to plague dairy producers throughout the summer months. There are a number of cooling strategies available to reduce heat stress and minimize effects on milk production and cow health. Certainly the use of fans to move air is the most used strategy and the most demanding on energy usage. Fans consume substantial electrical energy and will not provide adequate cooling when the air temperature is equal to or higher than the animal's body temperature. Sprinklers can help achieve maximum cooling effect and provide a greater return on energy costs. Air movement from fans and water from sprinklers can provide a powerful cooling combination.
Sprinklers in the feeding area, holding pen, and parlor exit alley will greatly increase the cooling power of the fans and further reduce the effects of heat stress on the cow. This cooling is coming from water evaporating from the haircoat and skin of the cow. Sprinkling with large water droplets is required to penetrate the haircoat. Sprinkling systems that are regulated by a timer and thermostat will provide adequate wetting without over-wetting the cow, udder, or footing area. A cycle of 2 to 3 minutes water spray and off 10-15 minutes will provide an adequate job of conserving water usage while sufficiently wetting the animal. There are a number of nozzle types that can work, depending on how close to the cows the sprinkler is mounted. Sprinklers over the feed bunk should have a 180 degree spray pattern, low pressure (10 pounds per square inch) spray nozzle and capable of delivering the equivalent of about .5 to 1 gallon per minute. The nozzles should be spaced 5 feet apart to get an overlapping coverage over the cows.
Fans will need to run continuously and should be capable of handling air flow rates of 11,000 to 20,000 cubic feet per minute. Fans can be hung above the sprinklers and tilted downward to 30 degree angles to direct the air flow on the cows. A rule of thumb for placing horizontal-axis fans is to mount 36 inch fans to move air 30 feet and 48 inch fans to travel air 40 feet. Fans should also be mounted in this manner over the freestalls.
REDUCING ENERGY INPUTS WITH A NUTRIENT MANAGEMENT PLAN
A major consideration for a manure nutrient management plan is to get the most possible plant nutrient value from the manure applied on cropland. As we see an increasing concentration of dairy animals per farm, an added concern dairy producers must deal with is the impact of excess nutrients on environmental quality. Nitrogen and phosphorus are the primary nutrients of concern. Excess nitrogen in the soil can leach down to the groundwater thus raising the nitrate levels in drinking water. Surface movement of nitrogen (N), phosphorus (P) and potash (K) in runoff increases the potential for surface water pollution. With these concerns in mind, a well planned manure management program will reduce the energy costs associated with crop fertility and the maintaining of a quality environment.
With the increasing public interest in environmental regulation for livestock operations comes the need for producers to have a well documented livestock waste management plan. Current Illinois law requires all livestock operations over 1000 animal units to have a written manure nutrient management plan. However, it is a good management decision for all livestock producers to prepare a manure plan. Producers who have a top-notch plan can improve their profits while protecting the environment and have a stronger defense in case of a pollution complaint.
Emphasis needs to be placed on maximizing the value of livestock manure. As energy costs continue to increase so will the cost of commercial fertilizers used for crop production. It is important to credit manure applications as a prime source of N, P and K for the growing crops. By using commercial fertilizer as a supplement, costs of crop production can be reduced and the increased value of these manure nutrients can be credited to the dairy enterprise. In addition, with less purchased fertilizer energy costs associated with its manufacture can be reduced.
In order to set up a manure management plan, producers need to:
- Know what nutrients are available from the dairy herd.
- Select fields based on crop needs and soil tests.
- Calculate amount of manure N P K actually available for crops.
- Determine and record manure application rates needed by field and amounts applied.
A plan should include location of farm, maps, manure inventory and provisional statements relating how livestock waste will be handled.
This topic is sponsored by the Illinois Department of Commerce and Community Affairs, Bureau of Energy and Recycling.