What Are Compost Bedded Dairy Barns?
In the U.S., the first compost bedded loose housing (CBP) dairy barns were developed by Virginia dairy producers in the 1980’s to increase cow comfort and longevity. The key component of a CBP dairy barn is a large, open resting area generally bedded with sawdust or dry, fine wood shavings that is tilled to support aerobic composting. Studies in Minnesota in the early 2000’s built a knowledge base which researchers in Kentucky have utilized during the past 5 years as the foundation for our research and extension activities on the CBP barns, herds housed within them, and assessing compost fertility. CBP barns fit within goals of sustainable agriculture for dairies with less than 500 lactating cows because of benefits to the cow (space, rest, exercise, and social interaction – Videos 1 & 2), the farmer (low investment, labor-extensive, reduced manure storage costs with composted manure under roof), milk production (milk quality, milk yield), and the environment (reduced ammonia and greenhouse gas emissions, odor and dust emissions, reduced energy consumption, improved manure fertility and flexibility to meet nutrient management plans). Operator experiences and research results of completed and on-going CBP barn projects are presented.
What we did
Our first activity was to assess the existing CBP barns in KY to establish the reasons for success. Fifty-five known existing CBP dairy barns in KY were visited from September 2010 to March 2011 to determine the management, barn construction details and management factors that lead to successful operation and herd improvements. Five areas of research were subsequently identified. Critics have expressed concerns about mastitis risks in barns. Environmental mastitis has been the main concern due to the bacterial load in the CBP barn compost. A study was conducted of mastitis incidence and milk Somatic Cell Count (SCC) of CBP barns relative to “gold standard”, sand bedded free stall barns. Dairymen also wanted to have more certainty of the compost nutrient value for land application. A study was initiated to determine N and P in compost and their release for plant uptake during the first year. For one year, bed data for temperature, moisture, nutrient content by depth, and barn climate were collected to understand the seasonal climatic effects on the compost bed and how quickly these effects are seen. Finally, bed tillage, using cultivators or rototillers, was evaluated for effects on bed performance.
What we learned
Facility design, ventilation, timely addition of fresh, dry bedding, frequent and deep stirring, and avoidance of overcrowding are the keys to a good working CBP barn. Poor management may lead to very undesirable compost bed conditions, dirty cows, elevated SCC, and increased clinical mastitis incidence. Most Kentucky dairy producers listed increased cow comfort and welfare as the main benefit to the CBP barn system, while others cited increased cow cleanliness, low maintenance nature of the system, and the barn’s usefulness for special needs and problem cows. Evaluation of annual bed performance data led to development of new compost bed management strategies. Instead of using the hygiene score for cows or bed temperature, moisture content was viewed as the primary measure since it was a leading indicator of the bed before failure. The time between a good performing bed and a poor performing bed was a matter of days when the moisture content exceeds 60% – wb. The comparison of CBP barns to sand bedded freestall barns validated producers’ observations of comparable SCC and mastitis incidence prevalence in CBP barns. Finally, CBP compost added to soil differs in P dynamics depending on soil test P level. In Low Soil Test P (STP) soils the CBP tended to slowly mineralize, and like inorganic P fertilizers, was subject to adsorption. In High STP soil, P in compost was first adsorbed, but then slowly released with time.
- Computational Fluid Dynamics (CFD) modeling of the compost bed management and barn design alternatives for demonstration to dairymen for planned and existing facilities.
- Effect of Rapid Eye Movement (REM) sleep on cow health, production and comfort.
- Mastitis incidence as affected by microbial ecology of the cow udder and compost bedded pack.
- Life Cycle Assessment (LCA) and economic analysis of system: milk production, barn, and compost disposal.
Joseph L Taraba, Extension Professor, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY – firstname.lastname@example.org. 859.218.4353.
Jeffery M Bewley, Associate Extension Professor, Animal Food Sciences, University of Kentucky, Lexington KY
George B Day, Adjunct Instructor, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY
Mark S Coyne, John H. Heick Professorship, Plant and Soil Sciences; University of Kentucky, Lexington KY
Michael Sama, Assistant Professor, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY
Randi A Black, PhD Graduate Student , Animal Sciences, University of Tennessee, Knoxville TN
Flavio A Damasceno, Professor (Associate), Departamento de Engenharia, Universidade Federal de Lavras, Lavras, MG – Brasil
Elizabeth A Eckelkamp, Graduate Research Assistant, Animal Food Sciences, University of Kentucky, Lexington KY
Leslie A Hammond, Graduate Research Assistant , Plant and Soil Sciences; University of Kentucky, Lexington KY
John Evans, Graduate Research Assistant, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY
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