This barn style started in the 1980s in Virginia, with the idea to improve cow comfort and longevity. Eliminating stalls and curbs allows cows to move freely. The barns have a concrete feed alley and open, natural ventilation with a 4-foot fence all the way around. The cows lay in the bedding when not being milked or eating.
Is compost bedding pack right for you?
Compost barns may require more upkeep than other barns, and climate should be considered. Central and eastern Texas have a longer hot season and are more humid than other regions in the U.S., causing more microbial action, so extra upkeep and extra bedding might be necessary.
Barn design considerations
A common barn style has a feed alley on one side with a concrete wall and a 4-foot fence around the other three sides. Sixteen-foot walls are also best for ventilation and machinery entering the feed alley. The roof should overhang 3 feet – 6 feet above the feed alley to avoid runoff into feed. Adding gutters to your barn will also help with runoff. Having open side walls is good for ventilation to remove moisture and heat.
What is composting?
The goal of composting is to produce heat, moisture and carbon dioxide through microbial breakdown of organic matter. Optimum moisture for a compost barn is 40% to 60%. The best temperature range of compost is a constant 110º to 140℉ measured 6-12 inches below the bedding surface. If the temperature is below 110℉, the microbial activity is too slow and vice versa for above 150℉. The nutrients in a bedded pack (carbon, nitrogen, moisture and microorganisms) come from the bedding, feces and urine of the cows, while the bedding encourages the microbial activity.
Bedding material options
Kiln-dried sawdust is the best option to stimulate the biological activity of compost because it has the best carbon to nitrogen ratio (30-to-1). Another good option is wood shavings because they encourage microbial activity. However, cedar shavings do not allow for microbial growth and therefore, are not a good option. Conversely, hay is not an ideal option as the absorption rate cannot maintain an ideal moisture level. Lime and sand are poor options as well because of their low absorption rate and inorganic properties, which limit microbial activity.
The main benefit of a compost-bedded pack barn is cow comfort. An open-facility design without curbs and side rails allows for easy movement, especially for lame or transition cows. Well-managed compost barns might also result in a reduction of somatic cell count and, subsequently, an increase in milk production. There is also more flexibility to house different breeds in one barn, compared to barns with stalls designed to a specific size suitable for only one breed. Another benefit is the two-in-one manure management. With a compost barn, the manure and bedding are managed in one place.
One downside of a compost barn is the increased area per cow needed. In a freestall barn, the area per cow is about 80 square feet, whereas in a compost barn, it is at least 130 to 140 square feet per cow. Additionally, bedding may be expensive or even hard to find at times, making management of your compost difficult. Another downfall is upkeep of bedding. Tilling the bedded pack is necessary at least twice daily.
A new bedding should start four to six weeks prior to temperatures dropping below 50℉ because the compost may not be able to keep heat production up otherwise.
To start, you need 1 to 2 feet of bedding. The biggest factor in upkeep is tilling two to three times daily using a rototiller (or modified skid steer attachment) at a 10 to 12-inch depth to expose oxygen. Tilling is crucial because oxygen is needed for aerobic fermentation for suitable composting. Air and moisture affect oxygen as well. Cows are using the compost as a bed and compacting it down, taking out the oxygen. If moisture is above 70%, more compaction will occur, reducing oxygen in the bedding. Moreover, cows will become dirty as the compost begins to stick to them.
Depending on your geographical location and the season, bedding may be needed more often because of moisture. Lastly, the compost-bedded pack should be completely cleaned out once or twice a year. In conclusion, deciding if a compost barn is right for you is a personal decision. If you have extra time and space for the upkeep and want longevity and cow comfort, a compost barn may fit your needs.
References omitted but are available upon request. Click here to email an editor.
This originally appeared in the Texas Dairy Matters newsletter.
L. Paige Bielamowicz is an undergraduate research assistant at Tarleton State University. Barbara Jones is an assistant professor at Tarleton State University, the director of the Southwest Regional Dairy Center and a research scientist at Texas A&M AgriLife Research in Stephenville, Texas.