Chapter 6 Animal housing features.
After completing the study of this chapter, you should be able to
* list and describe key features of a freestall barn.
* understand how each feature affects cow comfort.
* understand how each feature affects facility operation and maintenance.
* evaluate an existing dairy operation to determine if adequate freestall features exist or can be constructed.
* incorporate construction of freestall features into a dairy modernization plan.
alley-scraper drive unit
This chapter covers some features of freestall barns that are common across barn types and that have ramifications for cow comfort and labor efficiency. The following examples are only a subset of the total range of options available when constructing a new facility or retrofitting an existing building.
Modern dairy housing facilities are often large because they house large herds. These large barns must be designed for easy access by human traffic and equipment for feeding, bedding, manure removal, and animal movement. In cold climates, manure may freeze during severe weather conditions and require large equipment, such as a pay loader, to remove it. Plans on how to handle this type of situation must be considered in designing the building. Entry doors and connector barns must have enough clearance to allow such equipment to enter the barn.
Access to the barn by people should minimize walking distance, save time, and minimize exposure to outside elements. Review barn plans before construction. Consider all the activities required in the dairy, and then determine if the barn supports those access requirements. For example, providing a walk lane beside the holding pen and any connector barns will enable people to pass stalled groups of cows; including normal-sized doors at the end of each barn can eliminate the need to open large overhead doors whenever entry is required (Figure 6-1). Ventilation
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Dairy cows need a constant source of fresh, clean air to achieve their production potential. High moisture levels, manure gases, pathogens, and dust concentrations present in unventilated or poorly ventilated structures create an adverse environment for animals. Stale air also adversely affects milk production and milk quality. Proper ventilation consists of exchanging barn air with fresh outside air uniformly throughout the structures. The required air exchange rate depends on the temperature and moisture level of the outside air, and animal population and density.
Most modern dairy barns rely on natural ventilation to remove heat and humidity from the animals' environment. Natural ventilation of freestall dairy barns is widely used because it provides a very economical means to cool cows. A 1 mph wind is equivalent to a velocity of 88 feet per minute. Natural ventilation for a barn depends on building openings and building orientation. Barns should be oriented to maximize the airflow into the barn. In naturally ventilated freestall barns, exhausted air leaves predominantly though the sidewall during the summer and through the ridge opening during the winter. Since most barns are longer than they are wide, the length of the barn should be positioned perpendicular to the most prevalent wind during the time of the year with the highest heat patterns (i.e. if summer winds normally come from the south, the barn should be built with east-west orientation to take advantage of this wind). Openings on the sidewalls allow air to enter and escape, taking heat and humidity with it. Curtain sidewalls in cold climates enclose the barn on cold days and control the amount of air movement into the barn. Barns should never be completely enclosed; some barn openings should always be provided. Buildings should be designed with a minimum of one inch of eave opening on each side of the barn and two inches of roof opening at the top for each ten feet of width. During cold weather, curtains can be closed to this minimum amount, and then opened as temperature increases. During hot weather, the barn should be as open as possible to maximize the amount of air flowing thorough it. To accomplish this, sidewall heights of 12-14 feet are recommended. People considering higher sidewall heights should take into account the tradeoff between additional airflow and the light and heat radiated or reflected into the barn. Wide barns and barns in areas where wind directions change should be designed to be open at both ends (Figure 6-2). With naturally ventilated open-front freestall barns, an eave opening should be provided on the back wall to prevent swirling of air from the front.
Another factor to consider when attempting to maximize airflow is the proximity of the barn to other structures or land features. A high hill, wooded area, or adjacent building can serve as a wind shield and prevent airflow to the barn. The higher the obstructing object, the farther it should be from the barn being built. As a general rule, freestall barns are built about 100 feet from such obstructions. In many parts of the country, birds can be a problem when they enter the barn to roost and eat. Often barns are built with wooden trusses (Figure 6-3a) that provide a natural roosting place for birds, and this wood structure can also retard airflow within the barn. Other barn structure types, such as steel-framed barns (Figure 6-3b), minimize bird roosting, enhance airflow within the building, and increase visibility within the structure. Local prices, the intensity of the bird problem, and your objectives determine your choice of structure. One way to reduce bird problems is to install bird netting on the barn sides and over the roof opening, but this solution is not recommended. Birds often enter through open doors, and covering the roof opening can severely retard airflow during cold weather when frost builds up on the mesh (as shown in Figure 6-4).
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When building a freestall barn, you must pay attention to the concrete surface that the cows are exposed to. This surface must be smooth so that the animals' hoofs are not damaged by rough edges or abrasions, and it must have grooves to prevent cows from losing their footing when they slip. After new concrete is poured, all rough surfaces should be removed before cows are exposed to it. Often a large block of concrete or a metal blade is used to remove the abrasive elements on the concrete surface. Figure 6-5 shows these rough edges being removed with a portable grinder unit. Concrete grooves are normally placed parallel to the barn's manure alleys-to allow water to flow in flush barns and to prevent scraper blades from catching the edges in barns using scraper systems. Grooves should be 1/2 - 5/8 -inch wide and deep, with a sharp edge to catch an animal's hoof when the animal slips. Figure 6-6 shows how this producer chose to cut groves into the concrete after it was poured and dried. This technique often results in cleaner grooves, and may not significantly increase the overall cost of the project. Care should be exercised if grooves are floated into the concrete, to ensure that the resulting grooves have a distinct edge but do not produce abrasive places that can damage an animal's hoof.
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Proper lighting is very important because it must provide the proper environment for many tasks (including office work, cleaning milking equipment, and treatment of animals) and for the health of animals. A good working environment increases efficiency, comfort, and safety. Amounts of light required will vary, depending on the tasks that are being preformed. New buildings should be designed to support the lighting needs of the dairy operation.
All fixtures should be watertight and made of corrosion-resistant materials. Wiring should be surface-mounted cable or nonmetallic conduit. When selecting light fixtures, consider initial cost, efficiency, lamp life, color rendition, and starting characteristics. High illumination levels (100 foot-candles) should be planned for milking parlor operator pits, offices, toilets, milk rooms, and animal treatment areas. The average light intensity in barns must be at least 15 foot-candles at cow eye level; a normal recommendation for new facilities is to install lighting designed to deliver 20 foot-candles to allow for the effect of aging and dirt buildup on light fixtures.
Research trials have shown that supplemental lighting can increase milk production and feed intake. The primary objective of a supplemental lighting system is to provide summer day-lengths all year. Additional light is supplied so that milk cows are exposed to a constant 16-18 hours of light and a minimum of 6 hours of darkness each day (denoted "16-18L:6D"). The expected result of supplemental lighting for commercials herd is an 8 percent increase in milk production coupled with a 6 percent increase in feed intake. Cows do not respond immediately but are expected to adapt in several weeks.
Large herds with several milking groups milked 3X often present a challenge in providing six hours of continuous darkness (Smith, Harner, and Brouk 2003). Lights may need to remain on at all times to provide lighting for cattle moving to and from the milking parlor. Low-intensity red lights may be used in large barns to allow movement of animals without disruption of the required dark period of other groups.
Dry cows benefit from a different photoperiod than lactating cows. Recent research (Dahl, 2000) showed that dry cows exposed to short days (8L:16D) produced more milk (P G .05) in the next lactation than those exposed to long days (16L:8D). Based on the results of these studies, dry cows should be exposed to short days and then exposed to long days post-calving.
A producer planning a new facility should select a barn design that supports current recommendations for grouping of animals based on stage of lactation, breeding status, production level, and so on, but the design also should be flexible enough to be used differently if the need arises. Some operators have built five-row barns to house low-producing cows on the three-row side and high-producing cows on the two-row side; others have built barns with a long end (two large pens) and a short end (two small pens) to accommodate the different-sized groups expected. Some producers have built parts of the barn with smaller stalls to accommodate heifers. All of these decisions limit the ways in which the facilities can be used in the future. One way to build flexibility into a freestall barn is to design it with equal-sized pens that can be subdivided into multiple pens. When this is done, island waterers are often used at the dividing points. Figure 6-7 shows an island waterer that allows cows access from each pen to a single waterer. Management can easily change from housing two small groups to one large group simply by removing two gates.
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All of the approaches mentioned here have advantages and disadvantages. One thing to consider with the five-row option is how the roof will be designed. If each side has the same slope, rain and snow may be deposited on the feed. If the roof opening is placed at the center of the barn, each side will have a different slope. If a long-end-short-end barn is built, balancing the pens with the parlor size becomes more difficult. If pens are divided using island waterers, the back pen of animals will need to pass through the front pen to be milked.
A building should be designed to allow future expansion. Table 6-1 shows the capacity of a freestall barn built with one end longer than the other (a long-end-short-end barn). This barn initially had two pens on the long end that could be milked with a double-8 parlor in 60 minutes, and the short end had two smaller pens that could be milked in 47 minutes. When the herd was expanded and the parlor enlarged to a double-12, only one end of the barn needed to be extended to keep the same milking time relationship with the new parlor. Planning ahead for future expansions can save money in the long term, since land preparation is most economical if done with the initial construction.
Another growth factor to consider when a new facility is planned is the manure-removal method to be used both initially and in the long term. Producers often use a tractor scraper initially, to reduce capital investment, and plan to install automated manure-removal equipment later. By knowing which automated system will be selected, you can select the proper barn floor slope and reserve space for any additional equipment needed. In cold climates, reserve space inside the barn (Figure 6-8) to protect alley-scraper drive units and workers performing routine maintenance.
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Gates should be designed to allow quick and easy movement of animals and people throughout the facility. Opening and closing gates can be time consuming and frustrating when properly designed gate latches are not selected. Figure 6-9 shows two different types of gate latches. The quick-release latch can be quickly opened from either side with one hand and the gate moved in either direction. If the gate is rigid enough, this system allows a gate to be swung toward the latch and for it to latch automatically. The chain shown would have to be manually wrapped around the post and then hooked on the bolt head provided. Any latch system (as well as people-passes), should allow a person to move easily throughout the barn with minimal time and effort.
One problem with island waterers is where to store the divider gates when not needed. Scissor gates that fold up and out of the way help solve this problem. Figure 6-10a shows how scissor gates are used around island waterers, and Figure 6-1 Ob shows how scissor gates are used to form a drover lane across a freestall barn's feed alley. These scissor gates have also been effectively used for temporary or permanent separation of pens of animals.
Proper design of pens in the special-needs portion of a freestall barn allows one person to catch and restrain an animal for treatment. Figure 6-11 shows how a gate placed near the head-lock can be used to help direct the animal into the head-lock for treatment.
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Feed mangers should have smooth surfaces to encourage feed intake. Cows dislike an abrasive surface, and decomposed feed can accumulate on it, causing a foul smell. Smooth surfaces also allow for easy removal of uneaten portions of the diet. Constructing curbs like the one shown in Figure 6-12, which allow easy removal of feed, can improve labor efficiency and prevent buildup of feed in corners. Coating the surface (with an epoxy sealant, ceramic tile, or plastic panels) provides a smooth and easily cleaned surface. Any surface materials applied to the feed platform should be installed flush with the surface to prevent feed-scraping equipment from catching an edge of the material.
Most freestall barns are designed with four pens of cows that exit the barn through a center crossover alley. This requires animals to cross the drive-through feed alley. Scissor gates, electric gates, cattle guards, and many other systems are used to prevent cows from entering the feed alley. If cattle guards are used, they should be deep and the feed alley designed to prevent feed from accumulating under the rails. Figure 6-13 shows how the feed alley near the cattle guards can be boxed to allow cows to eat, but prevent feed from falling through the guardrails. This boxed feed area complicates feed delivery and cleaning of the feed alley, however.
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High-producing cows require large quantities of high-quality water. Each pen of cows should have at least two waterers, with a minimum of 1-2 inches of water access space per cow. Large pens should have a crossover every length of 15-20 stalls, which allows cows to move between feed alleys, waterers, and the freestall alley. A waterer should be placed at each crossover. Many different kinds of waterers are used. Commercially available models, like the one shown in Figure 6-14, are often easy to clean because of the smooth factory surface, whereas poured concrete waterers are more porous and more difficult to keep clean. As Figure 6-14 shows, water can be contaminated with manure if animals are allowed to stand in or near a waterer. Installation of a cattle guard over a tank, as shown in Figure 6-15, can prevent animals from standing in the tank, and a four-inch sanitary step around the waterer can keep cows slightly away from the tank and prevent them from defecating into it.
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Fans and Sprinklers
High-producing dairy cows must be kept at comfortable temperatures. Heat stress occurs when a cow's heat load is greater than its capacity to lose heat. The heat load includes the cow's own body heat as well as external heat from air movement and temperature, humidity, and solar radiation. Dairy cows do not perspire heavily, so they must rely on evaporation through respiratory heat loss. Heat-stressed cattle have high respiratory rates that result in reduced feed intake and low rumination, which negatively affect milk production. Modern freestall barns allow cows to take advantage of shade, fans, and sprinklers to reduce heat stress. Figure 6-16 shows a new freestall barn with fans installed. Smith et al. (2003) reported that cow cooling by evaporating water from the skin surface is a very effective method of relieving heat stress and decreasing milk loss during times of high heat. The use of low-pressure sprinkler/soaker and fan systems to effectively wet and dry the cows will increase their heat loss. Dairy cows can be soaked in the holding pen, exit lanes, and on feedlines. The goal should be to maximize the number of wet-dry cycles per hour. In the summer of 2001, a study was conducted at Kansas State University to determine the effects of soak frequency and airflow on respiration rates, skin temperature, and vaginal body temperature of heat-stressed dairy cattle (Brouk, Smith, and Harner, 2003). Sixteen heat-stressed lactating cows (8 primiparous and 8 multiparous) were arranged in a replicated 8 x 8 Latin Square design. Cattle were housed in freestall dairy barns and milked 2X. During testing, cattle were moved to a tie-stall barn for a two-hour period from either 1:00-3:00 P.M. or 3:00-5:00 P.M. on eight different days in late August and early September. Average afternoon temperatures were 88[degrees]F, with a relative humidity of 57 percent. During the testing period, respiration rates were determined every five minutes by visual evaluation. Skin temperature of three sites was measured with an infrared thermometer and recorded every five minutes. Treatments were four different soaking frequencies, with and without supplemental airflow: soaking frequencies were control (no soaking), and every 5, 10, and 15 minutes; supplemental airflow was either none or 700 cfm (cubic feet per minute). Each wetting cycle provided similar amounts of water for all treatments. Initial data were collected for three initial five-minute periods prior to the start of the treatments.
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Cows soaked every five minutes with supplemental airflow (5 + F) responded with the fastest and largest drop in body temperature and respiration rate, reducing the initial respiration rate by 47 percent at the end of 90 minutes of treatment. Soaking cows every five minutes without airflow (5) resulted in a similar response to soaking cows every 10 minutes with airflow (10 + F). Soaking cows every 15 minutes with airflow (15 + F) and soaking cows every 10 minutes without airflow (10) resulted in similar responses until the last 30 minutes of the study. Supplemental airflow without soaking (0 + F) resulted in little improvement over no soaking or airflow (0). Wetting had a greater effect on respiration rate and vaginal body temperature than airflow; however, the combination of wetting and airflow had the greatest effect. Respiration rates and vaginal body temperature were highly correlated. When cooling heat-stressed dairy cattle, the most effective treatment included continuous supplemental airflow and wetting every five minutes.
This data suggests that different cooling strategies could be developed for different levels of heat stress. Under severe heat stress, soaking every five minutes with fan cooling will be the most effective; under periods of moderate stress, soaking every 10 minutes with fan cooling may be adequate. Reducing soaking frequency when temperatures are lower could significantly reduce water usage. Data clearly indicate that the combination of soaking and supplemental fan cooling is superior to either single treatment. Used alone, soaking has more impact than fan cooling. The data indicate that about s of the total reduction in cow respiration rates was due to airflow, and the remainder due to soaking. Under periods of severe heat stress, soaking every 15 minutes with airflow is inadequate, and soaking frequency must be increased.
Cow cooling with soaking and supplemental airflow is very effective in reducing respiration rate. Many systems may be ineffective because they do not deliver adequate water to soak the cow or have an inadequate soaking frequency. To adequately cool cows in a four-row barn, Smith recommends that fans be mounted above the cows on the feed line and above the head-to-head freestalls. If 36-inch fans are used, they should be placed no more than 30 feet apart, and if 48-inch fans are used, they should be placed no more than 40 feet apart. Fans should be operated when temperature reaches 70[degrees]F, and they should create an air velocity of 4-6 mph and airflow of 800-900 cfm per stall or head-lock. Feedline sprinklers should be used in addition to fans. Feedline sprinklers should wet the back of the cow and then shut off to allow the water to evaporate prior to the next cycle. Application rate per cycle should be .04 inches per feet', and sprinklers should operate when temperatures exceed 70[degrees]E
High-Volume Low-Speed Fans
HVLS (high-volume low-speed) fans are configured as large diameter paddle fans with 10 blades. The blades range from 4-12 feet long, making the diameter of the fan approximately 8-24 feet. Such fans operate at speeds of 50-117 rpm (from larger to smaller diameter) and have been used in industrial buildings to circulate ventilation air at a low velocity (3 mph). They have also been used in poultry and livestock barns to provide supplemental cooling of animals by increasing air circulation and air velocity in the barn. A study conducted in several California freestall barns (Haag, 2001) used HVLS fans placed approximately 60 feet apart, mounted in the middle of the barn over the feed driveway. Research results found no difference in respiratory rates and milk production between the barns with HVLS and those with high-speed fan systems.
Kammel et al. (2003) reported that 20-to-24-foot HVLS fans installed in Wisconsin in 2001 were mounted at a height of 16-18 feet, which was typically one foot higher than the overhead garage door at the ends of the center drive-through feed lane, and were approximately 60-70 feet apart. The cost was approximately $4,000-5,000 per installed fan. Air velocities were measured at a height approximately six-inch above the cows' backs when they were lying or standing. Velocities of 200-299 fpm (feet per minute) were found over a 20-foot diameter from the center of the fans, which coincided with the feed bunk line. Air velocities of 100-199 fpm were found within 30 feet of the center of the fan, which coincided with interior freestall platforms. Horizontal velocities of approximately 100 fpm were found 40 feet from the fan center, which coincided with the outside alley and freestall platforms. Horizontal velocities in the barn were turbulent, similar to a light breeze. Air movement normally was above 100 fpm over most of the barn area (which is much less than recommended). Farmers reported improved air quality, reduced noise, drier alley floors, reduced bird populations, and less cow crowding, and they felt that the fans reduced loss of milk production during periods of high heat and humidity, compared to no fans.
Tunnel ventilation is a special yet simple summer ventilation system. Its goal is to concurrently provide air velocity and air exchange in a barn. "Tunnel fans" are placed in one endwall of a building. Fans are operated to create a negative pressure in the barn, causing air to be drawn into the opposite endwall opening. Once in the barn, the fresh inlet air travels longitudinally through the structure and is exhausted by the tunnel fans. For tunnel ventilation to function at maximum potential, all sidewall, ceiling, and floor openings must be sealed to form the "tunnel."
Tunnel ventilation is not generally appropriate for use in cool and cold periods because it can create cold and drafty conditions. Since tunnel ventilation is a summer-only ventilation system, another means of providing air exchange must be in place the remainder of the year. Natural ventilation is the most logical choice. One concern with tunnel ventilation is that as the air that moves longitudinally through the barn, it becomes increasingly contaminated with air pollutants, and at some point the air may no longer be fresh.
Gooch (2001) states that research has shown that air movement between 400 and 600 fpm can successfully reduce heat stress in dairy cattle. The tunnel fan system for a barn should provide a total fan capacity to achieve this 400-600 fpm air velocity and 1,000 cfm exchange rate per cow. Inlets should be sized to provide a minimum of one square foot of area for every 400 cfm of fan capacity. Recommended fan controls should turn on a pre-defined band of tunnel fans when the barn air temperature reaches 65-68[degrees]F, and additional fans at 71-74[degrees]F
Observation of tunnel-ventilated freestall barns shows that insufficient air movement may take place in the row of stalls adjacent to a completely closed sidewall. Opening the curtain wall slightly (2-4 inches) by raising the lower curtain from the bottom allows a small amount of air to enter along the length of the barn at cow level.
Since the key to making tunnel ventilation work properly is to move large volumes of air, installing a ceiling in the barn improves the performance of the tunnel ventilation system. This is contrary to the needs of a naturally ventilated barn, which uses the high ceiling area to dissipate and discharge stale air. To solve this problem, barns that will be tunnel ventilated in hot weather and rely on natural ventilation the remainder of the year can place baffles laterally across the barn at about 100-foot intervals.
Tunnel ventilation systems add measurable capital and operation costs to those of a naturally ventilated system, which must be offset by additional milk production in order for the investment to deliver a positive return. Naturally ventilated structures that provide adequate air exchange (and are outfitted with cooling fans placed over rows of stalls and the feeding area) remain the preferred system, but tunnel ventilation may be justified in new and existing barns that otherwise would provide poor cow environmental conditions.
When a freestall barn is being designed, its style and features should complement the management style of the operator. Initial capital cost as well as long-term operating cost, cow comfort, and convenience of animal handling should be considered. Financial constraints will often influence which features will be selected and the best time to implement them. Each operation is different, so priorities and decisions will vary.
1. What are three features of a freestall barn that affect ventilation?
2. What is the primary objective of supplemental lighting?
3. What is the function of cattle guards and where are they often used on a dairy farm?
4. What is the most effective way to cool heat-stressed dairy cattle?
5. Identify two reasons for the ineffectiveness of cow cooling and soaking systems.
6. List the primary issues that must be considered when designing a freestall barn that will later be expanded.
Brouk, M. J., Smith, J. F., & Harner, J. P, III. (2003, January 29-31). Effect of sprinkling frequency and airflow on respiration rate, body surface temperature and body temperature of heat stressed dairy cattle. In Fifth international dairy housing-proceedings (pp. 263-268). St. Joseph, MI: American Society of Agricultural Engineers.
Dahl, G. E. (2000). Photoperiod management of dairy cows. In Proceedings of the 2000 dairy housing and equipment systems. Managing and planning for profitability (NRAES 129, pp. 131-136). Ithaca, NY: Natural Resources, Agriculture, and Engineering Service.
Fulwider, W., & Palmer, R. W. (2003). Factors affecting cow preference for stalls with different freestall bases in pens with different stocking rates. Abstracts from the American Dairy Science Association. Journal of Dairy Science 86 (Suppl. 1), 158.
Gooch, C. A. (2001). Natural or tunnel ventilation of freestall structures. What is right for your dairy facility? (pp. 1-13). Ithaca, NY: Cornell University.
Gooch, C. A. (2003). Floor considerations for dairy cows. In Building freestall barns and milking centers. Methods and materials (NRAES 148, pp. 1-19). Ithaca, NY: Natural Resources, Agriculture, and Engineering Service.
Haag, E. (2001, May, 24). Cool cows for less: High-volume, low-speed fans offer huge energy savings. Dairy Today Magazine, 24.
Kammel, D. W., Raabe, M. E., & Kappleman, J. J. (2003, January 29-31). Design of high volume low speed fan supplemental cooling system in dairy freestalls. In Proceedings from the fifth international dairy housing conference, Fort Wayne, TX (pp. 243-252). St. Joseph, MI: American Society of Agricultural Engineers.
Palmer, R. W., & Bewley, J. (2000, January 29-31). The 1999 Wisconsin dairy modernization project--Final results report. Madison: University of Wisconsin.
Palmer, R. W. (2003, January 29-31). Cow preference for different freestall bases in pens with different stocking rates. In Proceedings from the fifth international dairy housing conference, Fort Wayne, TX (pp. 155-164). St. Joseph, MI: American Society of Agricultural Engineers.
Smith, J. F., Harner, J. P., & Brouk, M. J., (2003, July 9-10). Dairy facilities--Putting the pieces together. In Four-state applied nutrition and management conference, Lacrosse, WI (pp. 34-45). MWPS-4SD16. Ames, IA: Midwest Plan Service.
Smith, J. F., Harner, J. P., Brouk, M. J., Armstrong, D. V., Gamroth, M. J., & Meyer, M. J. (2000, January). Relocating and expansion planning for dairy producers. Manhattan: Kansas State University.
TABLE 6-1 Housing capacity (before and after expansion) of a freestall barn built with one end longer than the other. Initial Expanded Parlor size double-8 double-12 Parlor throughput 72 cph 108 cph One end 72 stalls 72 stalls Milking time 60 min 40 min Other end 56 stalls 108 stalls Milking time 47 min 60 min Total stalls 256 360 Herd size w/dry 305 hd 430 hd
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|Author:||Palmer, Roger W.|
|Date:||Jan 1, 2005|
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