Biosolids and livestock manure are valuable high-carbon soil amendments, but they commonly contain antibiotic residues that might persist after land application. While composting reduces the concentration of extractable antibiotics in these materials, if the starting concentration is sufficiently high then remaining residues could impact microbial communities in the compost and soil to which these materials are applied. To examine this issue we spiked biosolids compost feedstock with ciprofloxacin at a concentration (19 ppm), approximately 5-fold higher than normally detected by LC-MS/MS (1-3.5 ppm). This feedstock was placed into mesh bags that were buried in aerated compost bays. Once a week a set of bags was removed and analyzed (treated and untreated, three replicates of each; 4 weeks). Addition of ciprofloxacin had no effect on recovery of resistant bacteria at any time point (P = 0.86), and a separate bioassay showed that aqueous extractions from materials with an estimated 59 ppm ciprofloxacin had no effect on the growth of a susceptible strain of E. coli (P = 0.28). Regression analysis showed that growth of the susceptible strain was diminished when compost was spiked with a wide range of ciprofloxacin (0-160 ppm; P<0.007), consistent with adsorption as the primary mechanism of antibiotic sequestration. Because bioassays reflect the bioavailability of residues whereas analytical assays do not, we recommend that similar bioassays be incorporated into studies of other antibiotic residues to better assess the risk that these residues pose for proliferating resistant populations of bacteria.
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.
The purpose of this project was to study and promote the use of compost as an alternative horse stall bedding and encourage horse owners and managers to think more creatively about manure management. Our objective was to reduce bedding use, and improve manure management practices at equine facilities in Snohomish County, Washington State.
Recreational and professional horse owners contribute to maintaining agricultural open space and supporting the agricultural infrastructure and local economy. Horse owners have historically been overlooked as contributors to animal agriculture, and as a result many horse owners lack a basic knowledge about manure and nutrient management. They are not aware of their impact on water and soil quality. Disposal of used stall bedding is costly for horse owners in northwestern Washington State, and has a potentially large impact on water quality. Disposal practices often include filling in low spots and ravines, or building massive piles. Composting manure at high temperatures eliminates pathogens and parasites, stabilizes nutrients, and reduces odors and vector attraction.
What did we do?
The Snohomish Conservation District (SCD) worked with ten commercial and two private equine facilities to test the use of compost as an alternative horse stall bedding material. Facilities ranged in size from 5 to >20 stalls. The primary system used for composting and reusing bedding involved a micro-bin composter (O2 Compost, Snohomish, WA) and a Stall Sh*fter® (Brockwood Farm, Nashville, IN). Micro-bins were assembled on-site and filled with used stall bedding (Fig.1-2).
After 30 days of composting, the bin was emptied and the manure was separated from the bedding (Fig. 3). The composted bedding was then used in a stall (Fig. 4). Equine facility managers provided feedback on the effectiveness, perception, and impacts of using the compost as stall bedding. Results varied between trial sites based on type and quantity of bedding used, season, and stall management practices.
What have we learned?
Composted stall waste makes a soft absorbent bedding for horses or other livestock. Composted bedding is less dusty than shavings or wood pellets, darker in color, and has a pleasant earthy odor. There were no reports of composted bedding increasing stall odors or flies, or negatively impacting horse health. The best results were reported when mixing the composted bedding with un-composted bedding in equal proportions or two parts compost to one part bedding. There were some reports of horses with skin and respiratory conditions improving during the time they were on composted bedding, including thrush in the feet, hives and “rain rot” on the body, and “scratches” on the legs.
When separating the composted manure from the bedding, the amount and type of bedding determines the effectiveness of a bedding re-use system. Concern about appearances was more prevalent than concern about disease or parasite transfer. Even though barn managers were not entirely ready to make the switch to composted bedding, this project helped start many conversations (in person, through publications, and social media) about manure management and resource conservation. It was a great opportunity to help horse owners make the mental leap from “waste” to “resource”.
Future Plans
This project demonstrated that compost is a safe and effective horse stall bedding. Future work should be focused in three areas:
1. Developing systems for making composted bedding that are practical on a large scale and provide an economic incentive for large equine facilities to recycle their waste.
2. Outreach and education programs directed at horse owners who board their animals at commercial facilities. Would some horse owners be willing to pay a premium to board their horses at a facility that is managed in an environmentally sustainable manner?
3. Clinical trials to examine the effects of composted bedding on skin and respiratory conditions.
Author
Caitlin Price Youngquist, Agriculture Extension Educator, University of Wyoming Extension cyoungqu@uwyo.edu
I would like to thank all of the farm owners and managers who very graciously participated in this project and were willing to try something new. The contribution of time and energy is very much appreciated.
Thanks also to the staff at O2 Compost for their efforts, ideas, and creativity. This would not have been possible without them.
And Mollie Bogardus for helping take this project to the next level, and explore all the possibilities.
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.
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.
Future plans
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.
Authors
Joseph L Taraba, Extension Professor, Biosystems and Agricultural Engineering, University of Kentucky, Lexington KY – joseph.taraba@uky.edu. 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
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.
Managing horse manure may involve mechanical equipment, physical labor and conveying of manure. It is generally practiced outdoors in all types of weather. Composting is the aerobic decomposition of organic materials by microorganisms under controlled conditions. Microorganisms consume oxygen while feeding on organic matter and as a result, give off heat and CO2. In conventional composting, composters manage the process variables, feedstock, air, moisture and shelter, to optimize the natural decay process. Green, wet, nitrogenous feedstocks are mixed with brown, dry, carbonaceous material creating a carbon to nitrogen (C:N) ratio in the range of 20 to 30:1 along with the proper amount of moisture.
Horse manure happens to be one of the easiest manures to compost. There are several methods in and out of structures that can facilitate the compost process. The process can be simple properly shaped static piles, aerated and turned; and you can even compost to capture and use the heat or energy. Imagine capturing the heat from your manure to warm barns! The windrows or piles are then managed via monitoring and/or turning for proper air-flow and temperature in order to speed up decomposition, eliminate odors and destroy pathogens and weed seeds. Composting horse manure can be as simple or complicated as you choose. It can be used on site or exported for sale.
Authors
Bonhotal, Jean jb29@cornell.edu Cornell Waste Management Institute
The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2015. Title of presentation. Waste to Worth: Spreading Science and Solutions. Seattle, WA. March 31-April 3, 2015. URL of this page. Accessed on: today’s date.
