OCAMM Seminar Series
Manure Handling and Treatment


    Click on the title to view a summary of the seminar.  Presentation date in parenthesis.

Management of manure from the pig-on-litter system:  A Hong Kong experience
Dr. Sonia Tiquia, Iowa State University  (1999)
High-rise hog facility: Implications for nutrient management
Dr. Richard Stowell, Ohio State University  (1999)
Fly control for confined livestock and poultry operations
Dr. Ralph Williams, Purdue University (2000)
Scale effects in dairy: Economic viability, environmental sustainability, social acceptability
Dr. Normand St-Pierre, Ohio State University (2000)

Wetlands for treatment of milking center waste water
Jeff Lefever, USDA-NRCS and Dr. Tom Zimmerman, Ohio State University (2001)

Mastitis and bedding materials
Dr. Larry Smith, Ohio State University (2002)
Economic comparison of swine production systems
Jon Rausch, Ohio State University (2002)
An ecological treatment system for dairy wash water
Dr. Jay Martin, Ohio State University (2005)
Compost dairy barns in Minnesota
Dr. Marcia Endress, University of Minnesota (2007)


Management of manure from the pig-on-litter system:  A Hong Kong experience
Dr. Sonia M.Tequia, Iowa State University

Pig manure has been found to be the main contributor to stream pollution in Hong Kong, as most of the manure is discharged into the watercourses without any treatment. As a solution to the pig manure problem, the pig-on-litter (POL) system was initiated in 1987.  Also known as in-situ composting, pigs n this system are raised in pens, the floor of which is covered with a 30 cm thick layer of sawdust (bedding material), mixed with bacterial product to aid decomposition.  A 10-month study was carried out to study the specific role of bacterial product on the performance of the POL system.  The findings of these experiments revealed that the success of the system depends on proper management of the system.  It was also found that this in-situ composting process relies on the establishment and maintenance of suitable microorganisms.  This means that the pig manure itself is the source of microbes, and a proper combination of sawdust bedding with pig manure provides the necessary environment for these microbes to propagate.

The spent pig litter disposed from the POL system contains high concentrations of organic matter and nutrients, which can be re-utilized as a fertilizer and/or conditioner, but requires further composting in windrows to reach full maturity.  The time required for the spent pig litter varied with the operation strategies used in the composting process.  This study identified the best operation strategies for efficient composting of spent pig litter.  Thus, less frequent turning was observed to decrease the rate of composting and it took longer time to reach maturity.  On the other hand, moisture content in the range of 50-60% appeared to be suitable for an efficient composting.  Seasonal temperature also affected the rate of composting.  Composting during winter resulted in a lower temperature peak in the piles and thus a slower decomposition rate.  To combat this, the frequency of turning can be decreased such that a satisfactory thermophilic temperature is achieved.

Further composting of the spent pig litter in windrows was found to reduced the phytotoxic effects of the immature spent litter compost since it converted the biodegradable organic matter to a more stabilized product.  The availability of the chemical factors, which affect phytotoxicity of the spent pig litter, was also significantly reduced during composting.  Further composting of the spent pig litter also eliminated the pathogen Salmonella.  Results of this study revealed that a temperature of around 60-65oC for 2-3 weeks is enough to kill the pathogen Salmonella.


Dave Elwell (OARDC, Food, Ag and Biological Engineering) questioned the mixing of litter before sampling and whether or not pigs defecate in a particular area.  Tequia replied that 500 g samples were taken from 20 different areas and combined to form a composite sample.  She also confirmed that urine and feces were concentrated on one side of the pen which sometimes resulted in the addition of sawdust to reduce water content.

Elwell questioned whether the litter was used for more than one batch of pigs.  Tequia replied that this had been considered for economic reasons.  Her conclusion was that the litter could not be used more than 2 times due to increased salt levels.

Harry Hoitink (OARDC, Plant Pathology) commented that testing seed germination by planting directly on the compost is not the best method even though it is commonly used.  He contended that compost is normally used as a soil amendment at a rate of 10 to 15%.  At higher rates nitrate pollution becomes a problem.  Thus, higher salt levels could be tolerated if compost is used as an amendment.

Tequia commented that plants grown in the compost were also analyzed for accumulation of heavy metals because of the practice in Hong Kong of feeding copper and selenium to pigs.  No accumulations were found. 

Ted Short (OARDC, Good, Ag and Biological Engineering) questioned the size of the farms in Hong Kong.  Tonia responded that many were large and located in the new territories in northern Hong Kong.  She reported that approximately 20% of these farms use the pig-on-litter system but that pigs are not put into the system until they have reached 20 kg.  This is to minimize disease in young pigs.

Tequia verified Hoitink’s question that the source of sawdust for the litter is the furniture industry.

Short questioned whether there was a market for the compost.  Tequia replied that while farming has not been common in Hong Kong, ornamental plants and vegetables are grown in the new territories and the compost makes a good potting medium for ornamentals.

Hoitink asked the sale price of the compost, then concluded that it is approximately 10 times higher in Hong Kong than in the U.S.


High-rise hog facility: Implications for nutrient management
Dr. Richard Stowell, Ohio State University

The high-riseTM hog facility, located at Four M Farm in Darke County, was designed to permit conventional production practices while meeting three objectives: 1) reduce moisture content, 2) decrease odors and 3) create a product with increased value and acceptability.  Conventional practices include fully slatted floors, standard pen size and arrangement, and much of the ventilation system.  Innovations implemented to meet the objectives include an above-ground manure collection and modifications to the ventilation system.  An in-floor duct network forces air through the bedding material and manure to promote drying, maintain aerobic conditions, and encourage composting.  Exhaust fans on the lower level pull air in through the attic and distribute it, reducing odors on the upper level and enhancing drying of the manure.  Results from the first year of operation (three groups of hogs) indicate a 62 to 75% reduction in volume, a drier product, and a higher nutrient content per ton.  Ammonia and hydrogen sulfide levels on the upper floor were significantly reduced.  Pig performance in rate of gain and days to market was similar or better to a deep pit facility.  The challenges to be resolved include compensating for dunging habits that result in non-uniform wetting which inhibits composting.  Also, air quality in the lower level could be improved.


Dan Mahan (OSU, Animal Sciences) asked if the hogs had been fed yucca.  It has been shown to be effective in trapping ammonia.  Stowell replied that this has not been studied at the facility because of the need to limit the number of variables in the initial study.  However, there is the possibility of studying the effect of yucca or another feed or manure additive on ammonia release.  Harold Keener (OSU, Food, Agricultural and Biological Engineering) noted that the extent to which ammonia is a problem at the facility needs to be documented before it is corrected.

Fred Michel (OSU, Food, Agricultural and Biological Engineering) asked how ammonia levels compare to deep-pit manaure storage.  Stowell noted that comparison data is from different years and a different location.  A hoop-house facility in Minnesota showed close to 20 ppm of ammonia compared to a mean of 4.3 ppm (range 10 – 19 ppm) in the upper level of the high-riseTM   facility.  Air quality studies from a flush or pull plug facility, which is supposed to reduce ammonia levels, would provide a better comparison.

Sonia Tequia (OSU, Food, Agricultural and Biological Engineering) questioned whether the reuse of the swine bedding and manure for two groups would result in an accumulation of salts and heavy metals that could limit the product’s use as a compost.  Stowell responded that the acceptability of reusing the bedding and manure was based on moisture absorption and air distribution.  Keener noted that, after the second group of hogs, the product was brought to Wooster and composted.  Keener’s understanding was that it was  considered acceptable as a soil amendment.

Tequia questioned whether layering of manure and bedding would be more effective than an initial application of 18 to 30 inches of bedding.  Stowell replied that as a standard practice layering is not feasible due to labor requirements and spreading limitations.  However, one to two times during grow out, bedding was added to heavily dunged areas.  The current focus is to develop a method to mix the manure to achieve even moisture distribution that will promote composting.  Keener also noted that the design of the duct network requires a minimum of 18 inches of bedding for effective air distribution.

Michel asked if odors increased after removal of the product.  Stowell noted that there was a spike in gas levels during clean out.  Four M Farm is doing on-site composting of the product and odors are difficult to detect.

Tequia commented that producers seem to focus on whether or not the facility can increase production performance rather than minimize environmental impacts.  Stowell observed that many producers currently have a low environmental impact as they have enough land for spreading manure.  Thus, there is little incentive to change without increased performance.  However, this situation is changing as less land is available and urban encroachment continues.

Tequia inquired about the preferred bedding material.  Stowell responded that wood shavings and corn stover were most effective.  The bedding material must be porous to absorb liquids and not too fine.  Preliminary data on chopped wheat straw indicate that it is not as absorbent.  Keener noted that wood shaving can be recycled through the system whereas straw and some other materials can be used only once.  Stowell commented that the market for the end product must also be considered and the yard and garden markets prefer a wood component.

Ted Short (OSU, Food, Agricultural and Biological Engineering) asked about changes in the design for new facilities.  Stowell replied that the single alley located down the center of the original facility has been changed to two alleys – one on each side.  Dunging habits will concentrate the manure toward the center axis of the building.  Also, removal of centralized pillars on the lower level will improve manure handling.  Another change being evaluated is heat recovery from the aeration system.  During cold weather, this should improve drying and reduce heating costs.

Short asked if there were any plans to use biofilters on exhaust fans.  Stowell responded that they are a high priority for secondary research.

Mahan asked if the nutrient content comparison had been made on a dry matter basis.  If this is not the case, would such a comparison result in less of a difference?  Stowell replied that nutrients measured on a dry matter basis would probably be closer due to dilution effect of bedding: however, it would have little meaning as it does not reflect the producer’s needs.  An “as is” basis must be used because that is how the producer will handle the product.


Fly control for confined livestock and poultry operations
Dr. Ralph Williams, Purdue University

Integrated pest management (IPM) is the most effective strategy for controlling flies in livestock manure but requires an understanding of fly’s life cycle and behavior as well as control methods. Flies are most vulnerable during the larval and adult stages.  Houseflies prefer pure manure with over 30% moisture and rarely migrate more than ½ to 1 mile from preferred breeding sites.  Primarily a nuisance, houseflies have the potential to transmit disease and can leave spots of fecal matter or vomit on eggs in heavily infested laying facilities.  The little housefly is slightly smaller and prefers a dryer manure and shadier site and can migrate 10 to 15 miles from the site.  While both species of houseflies are common to poultry facilities, the stable fly is more common in livestock facilities with bedded present.  These flies can suck blood, which can have a negative impact on beef and milk cattle.

IPM requires a systems approach to fly control that uses a combination of various methods, such as cultural controls, manure management, biological controls and mechanical methods.  Providing good sanitation and reducing moisture in the manure create an environment not conducive to fly breeding.  By maintaining a heterogeneous fauna in the manure, living organisms minimize flies by feeding on or competing with them.  While insecticides can be effective, they need to be applied correctly and during the proper stage of development as well as selectively to minimize genetic resistance. 


Ben Stinner (OSU) asked how the C:N ratio (carbon:nitrogen) or composting affects cultural control.  Williams noted that the heat generated during composting has the greatest impact in reducing fly populations.  Anaerobic bacteria and the pH of compost may also play a role but more research is needed.  Stinner commented that a change in C:N ratio will have a greater effect on the heat than on the environment.

Harold Keener (OSU) questioned the time frame needed to break the fly cycle.  For example, at Daylay Egg Farm, manure is removed via belts to the composting facility 3 days after it is generated. Williams responded that the breeding cycle is approximately 4 to 7 days but noted that a belt system may leave some manure behind.

Keener asked if flies could develop at temperatures above 42 degrees C.  Williams agreed and added that the anaerobic conditions that can develop during composting may also have an impact.

Paul Painter (OEPA) questioned the economics of pest control.  What would be the cost/dozen eggs to a large producer which uses biological methods, pesticides and a consultant?  Williams commented that the most recent study was 10 to 15 years ago.  At that time, a cost of 6-8 cents/bird/year was calculated.  Williams noted that IPM costs are not prohibitive and presented, as an example, a large egg producer that used an expensive insecticide program to control flies.  By implementing biological control, the producer was able to significantly reduce its cost.

Kevin Elder (ODNR) asked if the break out of flies commonly seen in the spring is predictable.  Williams replied that there is a yearly increase in the spring.  During the cold, winter months, the pupae develop very slowly.  As temperatures warm in the spring, the conditions are right for adults to emerge.  Williams recommended watching weather patterns and being prepared to use insecticides at this time.  Elder questioned whether feeding Larvadex at this time would be effective.  Williams noted that this pesticide affects newly emerging larva not pupae.  Also, it is only effective when it is being fed, not as an accumulation in the manure.

Ted Short (OSU) asked what the method for control is if climate changes can be predicted.  Williams recommended maintaining good moisture control to minimize the number of pupae.  However, winter months can make moisture control difficult due to condensation.

Keener asked if pheromones are effective in keeping flies inside a facility.  Williams noted that they compete with other odors that are attractive to flies and that many are very volatile.  The most effective use is in fly bait.

Billie Lindsay (OSU) asked it houseflies harbor bacteria that cause human diseases.  Williams responded that Salmonella and E. coli have been removed from flies in the lab, but there no literature or data pinpoint flies as the source for a disease outbreak.  Although it is difficult to link flies to human disease, they are considered a potential vector for pathogens.

Elder questioned whether the bacteria and molds that seem to be very effective in controlling fly populations in Europe are being studied in the US.  Williams noted that researchers in California and North Carolina are studying fungi mold for fly and beetle control.  The molds have potential but are slow acting and, currently, there is no commercial production.  In addition, a couple of bacterial subspecies of a product used to control mosquitoes, shows promise for fly control.

Scale effects in dairy: Economic viability, environmental sustainability and social acceptability
Dr. Normand St-Pierre, Ohio State University

Economies of scale can be realized on livestock farms due to improved technology and automation.  Data collected from 253 New York dairy farms for more than 50 years indicate variances in terms of tillable land, labor efficiency and capital efficiency.  Large farms (>300 cows) show a decrease in acres required for feed per cow, primarily as the result of an increase in hay production per acre.  Milk production per tillable acre on large farms is twice as much as on small ones (40 – 55 cows).  Labor is more efficient for larger farms with 45 cows per full-time equivalent position (FTE) for large farms compared to 35 cows per FTE for small farms.  Technology favors capital efficiency for large farms that can track individual cows and provide the most efficient milking system.  While small farms may appear to be economically viable, this is due to small debt and large equity which is not included in evaluating capital costs.  However, they are not economically sustainable in the long term.

The economics of milk production are also affected by whether the objective is economic performance or nitrogen efficiency.  Analysis of income over feed costs are $5.86/cow/day if the objective is maximizing income/feed cost but are $5.16/cow/day is the objective is nitrogen efficiency.  However, studies indicate that a diet containing high-lysine crude protein of 16.9% complemented with ??? results in the same milk production as a diet containing crude protein of 19.3% and reduces nitrogen excretion.  Grouping of cows to ensure greater uniformity for selective feeding can also improve nitrogen efficiency, with six groups maximizing efficiency.

Although current economics indicate that the smallest, efficient milking parlor is 650 cows milked 3 times per day, Ohio is experiencing resistance to new or expanding or farms of this size.  While public education and hearings have been promoted to overcome this barrier, their effectiveness has been limited.


Steve Loerch (OSU) asked if the trends seen in the New York data continue for 5,000 head herds.  St-Pierre responded that only about 5 of the herds in New York have more than 2,000 cows making extrapolation difficult.  Topography affects farm size as the hilly terrain requires manure to be carried larger distances for application, reducing economics..  Dairies in flatter terrain, such as the Western U.S., do see economies of scale with herds greater than 2,000 head.

Ted Short (OSU) questioned whether the economic analysis included the cost of the land needed for manure application and whether a nitrogen or phosphorus standard was used.  St-Pierre noted that the opportunity cost of holding land was included but that nutrient balance is a different question and was not addressed. While the analysis was a business summary, the 2 acres per cow available should be able to allow P balance.

Loerch requested a summary of the social concerns prevalent in Ohio and speculation as to why they may be different from other states.  St-Pierre responded that, traditionally, there have been few livestock operations in the croplands of northwestern Ohio.  However, as crop profitability has decreased, farmers are looking for additional markets such as livestock for their grain.  Also, during the 70’s and early 80’s, high milk prices provided little incentive to increase efficiency of dairy operations.  In the western U.S., there have been greater incentives to improve efficiency because lower milk prices have been more common.  Ohio also has a greater population density than many states, allowing small farms to supplement income in the local job market.

Jody Tishmack (Purdue) described observations of a Southern California dairy reserve with 5,000-10,000 cows.  The ammonia and fly populations were noticeable and a guide commented that nitrate pollution of the groundwater is affecting animal longevity but not production.  She questioned the regulatory climate.  St-Pierre responded that without first-hand knowledge it is difficult to respond.  The area is traditionally concentrated with dairy operations and it may be that, even with some pollution, neighbors find it preferable to L.A.  In general, California has stringent environmental regulations.

Kevin Elder (ODNR) asked if similar data on phosphorus efficiency are available.  St-Pierre said no as it is more difficult to analyze.  Phosphorus may accumulate in the short term (“bone storage”) so it does not move in and out of the system as quickly as nitrogen.  Historically, phosphorus has been cheap and recommended amounts are often increased by up to 30 %.  In addition, by-products used in dairy feed are often high in phosphorus.

Wetlands for treatment of milking center wastewater
Jeff Lefever, USDA-NRCS
Results on monitoring wetland for treatment of milking center wastewater
Dr. Tom Zimmerman, Ohio State University

Treatment wetlands are an option for treating milkhouse wastewater for dairies with fewer than 100 cows.  The stems of wetland plans filter suspended solids and provide a substrate for the microorganisms that can reduce biological oxygen demand (BOD), nitrogen, phosphorus, trace metals and pathogens.  Prior to construction of a wetland, the topography, soil characteristics, hydrologic activity, farm enterprise, aesthetics and cultural resources of the site must be evaluated.  Pretreatment of milkhouse wastewater via a settling basin, lagoon, or dilution may increase the effectiveness of the wetland to meet target levels of 1,500 milligrams/liter (mg/l) total solids and 100 mg/l ammonia.  The size required for a treatment wetland may be determined by the evaluating the BOD produced by the animal and uptake by plants or by maintaining a hydraulic residence time of at least 12 days.

Surface flow treatment wetlands were constructed on three small dairy farms (~60 head) in Wayne County to evaluate the effectiveness of treating milkhouse wastewater.  Wastewater drained to a holding pond on one farm before entering the wetland while the other two drained directly to the wetland.  All three farms used a series of three wetland cells with water following a sinuous pathway through each cell before reaching the next.  Water leaving the third cell drained to a filter strip to prevent discharge to waters of the state.  The results of the study indicated that treatment wetlands can be effective in treating milkhouse waste and that a holding pond may provide pre-treatment.  Water in the third cell often met or exceeded drinking water standards.  However, as the wetland ages, its effectiveness diminishes and vegetation and accumulated sediments may need to be removed to rejuvenate it.


Mike Monnin (NRCS) asked if the hydraulic retention time correlated with tests or whether some water was moving more quickly through the cells.  Lefever responded that it was difficult to follow water directly through the system, but a short circuit was never detected.  The wetlands were designed for a hydraulic retention time over 24 days (more than 2x the requirement).

Monnin questioned whether levels of pollutants in the wastewater varied with rainfall.  Lefever noted that the color of the water in the cells varied with the seasons but not with rainfall. 

Lynn Willett (OSU) questioned how precipitation and evaporation were accounted for assuming the milkhouse wastewater load was consistent.  Zimmerman responded that while the wastewater load was consistent, the evaporation/precipitation was not taken into account and may have resulted in some discrepancies in the data.

Maurice Watson (OSU) noted that the duckweed tested in the study had 1700 ppm manganese.  Because this is a toxic level for many plants, Watson suggested duckweed is an accumulator. 

Jay Martin (OSU) questioned whether the halo growth pattern of cattails in one wetland cell was a function of water depth.  Zimmerman responded that the reason for the halo is not known.  The maximum depth of the cell is approximately 2 feet.   Although the sides are shallower, cattails can usually withstand depths of 2 feet.

Jody Tishmack (Purdue) asked if any subsurface flow wetlands (gravel media with no water visible at the surface) have been successful in treating wastewater.  Lefever reported that none had been used in a cold environment.  The University of Texas in Stephensville has been developing and monitoring a subsurface flow system to treat domestic wastewater. 

Lucy Ward (OSU) asked if there were any recent data on the dairy treatment wetlands.  Zimmerman noted that the data presented is about 5 years old and no follow-up has been done.  Currently, only one of the three dairies is still in operation.

Fred Michel (OSU) asked if treatment of the wastewater occurs during the winter when there is little plant growth and whether the surface freezes.  Zimmerman noted that the cattails are dormant but there is some treatment although it is reduced.  A thin crust of ice can form on the water.

Michel questioned the composition of the base of the wetland cells.  Zimmerman explained that the native soil is compacted using standard methods.  Martin asked for an elaboration on the design and vegetation of the wetlands.  Lefever noted that the cells were primarily dug into clay based soil which was compacted to reduce permeability.  On one farm, the cells were benched into a hill with a dam constructed on the downslope.  Vegetation was obtained locally, primarily from ditch diggings.

Michel asked if neighbors complained of increased mosquitoes.  Zimmerman noted that there were no complaints.  An increase in mosquitoes was not noted during testing but there was some odor.  The sites were located to minimize odor problems with neighbors.

Michel asked if there is a simple method for measuring the volume of wastewater entering the system.  Lefever responded that flow meters used for sanitary wastewater systems had been investigated but they are designed for a consistent flow.  Milkhouse waste has large, intermittent flows.  Zimmerman noted that flow meters are very expensive.

Susan Mykrantz (Farmshine Publication) recalled that fish had been used at one farm to control mosquitoes.  Lefever agreed but the fish were tropical and did not survive.  Zimmerman noted that wildlife at the sites included turtles, mallard ducks, frogs and muskrats.

Mastitis and bedding materials
Dr. Larry Smith, Ohio State University

Mastitis is an inflammation of the mammary glands which is primarily caused by bacteria entering through the teat end and causing an infection.  The more bacteria placed on the teat end the greater the probability that infection and inflammation will occur. Mastitis, the most costly disease in animal agriculture, results in a reduction of milk yield and milk quality.  The major bacterial pathogens causing the disease can be categorized as either contagious or environmental pathogens.  Contagious pathogens are transmitted from infected glands to uninfected glands primarily during the milking process.  Contagious pathogens tend to cause subclinical infections that are most often detected by increased milk somatic cell counts (SCC) and are often the cause of high herd bulk milk SCC.  Significant control of contagious pathogens is achieved by post milking teat dipping in effective germicidal teat dips, total dry cow therapy and culling.  Bedding materials play little or no role in contagious mastitis.

The environmental bacteria are transferred to teat ends by contact with the environment and a major environmental contact with the teat end is bedding materials.  Infections caused by the environmental bacteria are likely to cause a case of clinical mastitis in addition to high SCC in infected quarters.  Clinical mastitis is visually abnormal milk and is generally not added to the herd bulk milk.  Thus, the impact of environmental pathogens on herd bulk milk SCC is reduced by comparison to the contagious pathogens.  Cows are susceptible to new environmental pathogen infections during all stages of lactation and the dry period and increased rates of
new infection are noted at the beginning of the dry period, around calving, during summer months and rates are higher in housed cows than cows on clean, green pastures.  Risk factors associated with housing are bedding materials, stall design, ventilation and management of the stalls, manure in alleyways, etc.

Organic bedding materials, such as straw, sawdust, manure solids, pelleted corncobs and recycled newspaper, provide a food source for bacteria and absorb moisture whereas inorganic materials, such as sand, do not.  Research indicates that bacterial contamination of teat ends is higher when cows are bedding with organic materials compared to inorganic bedding.  Particle size and other properties of the bedding can also influence the amount of teat end contamination.  Sawdust and wood products in general are known to contribute to coliform mastitis problems while straw bedding is often associated with increased amounts of environmental mastitis caused by Streptococcus uberis.  For cows that must be housed, sand that is dry, free of clay and well maintained is preferred over organic bedding.


Ted Short (OSU) questioned whether mats used in lieu of or with organic bedding materials are effective.  Smith commented that mattresses are not a solution to environmental mastitis as some form of bedding must be used (generally sawdust) or the backs of stalls will become heavily contaminated with manure and it is know that hock problems will develop if some bedding is not placed on the surface of the mattresses.

Harold Keener (OSU) noted that 60 pounds of sand are needed per cow per day which becomes a materials handling issue.  Smith replied that if stalls are properly designed, 40 to 50 pounds is more typical.  Many farms feel that the reduction in mastitis infections is worth it. However, help is needed to find ways to handle the manure/sand mixture removed from barns.

Keener asked if data were available for a New York dairy which reportedly uses composted manure as bedding.  Because composting changes the characteristics of the manure, the incidence of mastitis is reduced.  Smith replied that compost is still an organic material so can serve as a food source.  A couple of studies using compost as bedding were inconclusive due to small samples and short duration.

Fred Michel (OSU) asked how pathogens are quantified in the various studies of bacteria counts and suggested counts should be on a volume rather than weight basis.  Smith replied that the standard measure is number of organisms per gram of bedding material.  The best test and far more expensive, is to determine the number of bacteria contaminated the teat end.  This is done
by swabbing the teat ends and growing the bacteria on an appropriate medium.  He suggested that because sand is more dense than other bedding, counts should not be on a volume basis.

Keener suggested that for the farmer, the final proof is in the somatic cell count.  Smith noted the two primary measures of mastitis in dairy herds is herd bulk milk SCC and cases of clinical mastitis.  It is illegal to add milk from clinical quarters to the bulk tank so many infections caused by the environmental pathogens have minimal impact on the bulk milk SCC.  Thus, the somatic cell count in the bulk tank does not always reflect the degree of infection in a herd.

Michel asked if any dairies clean and recycle the sand.  Smith replied that, while there have been inquiries, no data exist.  Joe Christner (OSU) mentioned that a Wisconsin study is using recycled sand.

John Pecchia (OSU) noted that for samples taken from a local dairy producer's sand separation lagoon system, organic counts vary significantly depending on the sample location.

Willett questioned why it's not feasible to wash such large quantities of sand.  Michel noted that large volumes of water are needed.  Keener referred to a Michigan dairy which tried cleaning the sand 3-5 years ago, but the large volumes were a problem.

Michel asked if the long-term supply of sand is limited. Smith was not aware of any problems.  Tom Noyes (OSU) noted that he'd heard of more problems with a shortage of sawdust.

Short noted that although sand is beneficial for mastitis control, some farms, such as a large Pennsylvania dairy, have returned to organic bedding to allow for methane generation.  Smith noted that it depends on priorities with some farms willing to have some reduction in milk quality as a trade off.  It should also be noted that the majority of new farms being constructed in
Ohio are using sand bedding.

Economic considerations for swine production systems
Jon Rausch, The Ohio State University

The evaluation of different feeder pig production systems must take into account non-market impacts, such as odors, pathogens, particulate matter, as well as production parameters, revenues and fixed costs.  The three systems studied were the: 1) conventional system (CS) with full confinement, liquid manure and mechanical ventilation; 2) high-rise hog (HRH) system with full confinement, solid manure and mechanical ventilation; 3) hoop house (HH) system with full confinement, solid manure and natural ventilation.  The production factors analyzed included starting and ending weight, days on feed, average daily gain, feed efficiency, days to market, mortality, and turns/year.  Although the HRH demonstrated higher daily gain, fewer days to market and higher feed conversion, it had the highest fixed costs and electricity/fuel costs.  When manure handling cost, including bedding, hauling and equipment, were considered, the HRH had the lowest cost.  In the final analysis, the return to management per pig was highest for the HH, primarily due to the low capital investment required.  However, this analysis does not account for potential costs to protect the environment or address neighbor’s concerns.  For example, the HRH system reduces odors by 53%.  To achieve a comparable reduction in a CS, biofiltration, at a cost of $2.44 per pig space, would be needed.  As environmental and social issues become more prevalent, their costs will need to be considered.


Harry Hoitink (OSU) asked the source of the nutrient values.  Jon noted that for the solid manure systems, the values were from laboratory analysis, and for the liquid manure systems, the values were averaged from databases. 

Hoitink noted that nutrient concentrations do not necessarily reflect the value of the manure.  For example, HRH manure was sold at a nursery for $12 to $22 per cubic yard ($24 to $44 per ton).  As the manure becomes dryer and more stable, that value increases.  In field agriculture, the manure provides more than just nutrients.  He suggested that value-added markets need to be pursued before farmers will adopt more costly technologies.  Jon agreed and noted that if the land base does not increase as animal density increases, manure needs to be in a more solid form to reduce the expense of hauling. 

Hoitink suggested that biofiltration can be used to control odor during storage, but that there is also an “odor cost” during field application.  Dave Elwell (OSU) noted that composting can significantly reduce the odor for field application.  A study of HRH manure that had been composted for 3 to 4 weeks resulted in a 98% reduction in odor.

Harold Keener (OSU) asked Rausch to comment further on why the hoop house is not being readily adopted in spite of its lower capital cost.  Rausch noted that there is an economic advantage to the hoop house for small, contact farms or niche markets.  However, for large commercial facilities, the number of houses required compared to conventional or HRH buildings results in increased labor.  There is also greater difficulty in sorting and handling the hogs since the bedding and manure pack causes problems in operations such as opening gates.  He speculated that there could also be a stigma attached since there is less curb appeal.

Hoitink questioned whether increased disease is a factor for the hoop house.  Rausch noted that it’s possible after numerous cycles if sanitation is not adequate.  However, such a problem has not been indicated in conversations with Iowa researchers nor from the number of losses due to death.

Hoitink asked whether the management issues and costs of the conventional liquid system will eventually lead to it no longer being a viable alternative.  Jon replied that alternative systems are needed but costs must be a consideration. 

Hoitink commented that where high mortalities were noted in two of the six operations observed in the HRH, more replications are needed to evaluate whether they are coincidental or whether the system had an effect.  Rausch agreed and noted that the mortalities in the conventional system were based on 66 operations with only 6 for the HRH.  Thus, spikes in the conventional system have less impact on mean values.

Hoitink questioned the average life for a HRH building.  Rausch noted that 7 to 10 years was used based on IRS depreciation factors but that 10 years is probably realistic.  Hoitink noted that OWDA (Ohio Water Development Authority) has funds available to help finance HRH facilities because the system reduces the risk of water quality impacts as compared to a conventional system.

Ted Short (OSU) asked if there were any differences in feed efficiency.  Rausch replied that there were, but they were not significant.  (conventional – 2.62 lbs of grain per lb of gain; HRH – 2.64 lbs of grain per lb of gain; hoop house – 3 lbs of grain per lb of gain)

Keener noted that other manure issues at the HRH facility have arisen based on operational experiences.  Although early observations indicated good drying of the manure, additional data has indicated that turning of the manure is needed to meet initial expectations.  Commercial facilities have not been as successful as the original research facility in keeping manure dry which may reflect variances in management.  A different approach such as using bedding in a system that allows liquids to drain to a holding tank may produce dryer manure.

Keener also suggested that ammonia losses are also becoming an issue for livestock facilities.  Although the HRH facility has reduced odor, ammonia losses need to be reduced via capture within the building or by controlling its release from the manure.  If liquids can be separated from the feces, ammonia emissions should decrease.

An Ecological Treatment System for Dairy Wash Water
Dr. Jay Martin, Ohio State University

Ecological treatment systems are similar to natural wetlands in which the sun is the primary energy source and microbial interactions in aerobic and anaerobic environments degrade waste.  The difference is that the treatment is controlled and occurs in tanks in a smaller area.  Although ecological systems have been successful in economically treating municipal wastewater, dairy wash water presents a challenge due to BOD (biological oxygen demand) and ammonia levels that are 3-10 times higher.   A small-scale system was designed with four replicated lines to treat 340 gallons of wash water per day from the OSU Waterman dairy barn.  The wash water was collected from the manure holding pond and added to the system consisting of the following components:  1) anaerobic digester to break down BOD; 2) anoxic reactor with low levels of dissolved oxygen for denitrification of ammonia; 3) aerobic reactor with additional oxygen for nitrification; 4) open aerobic reactor with vegetation to break down BOD, nitrify ammonia and uptake phosphorus; 5) stratifier for settling of solids; and 6) marsh for denitrification and phosphorus uptake.  The wash water circulated between components 1 through 5 before moving to the marsh and had a total hydraulic retention of 16.6 days.  The system was in operation from June through October 2004and resulted in significant reduction in ammonia, BOD and coliform bacteria as well as a reduction in nitrates and phosphorus.   However, as the adsorption of phosphorus to mineral matter is expected to decrease over time, an additional additive or replacement of mineral matter may be needed.  Continued research on the system will address the challenges of plant die off during winter, separating solids before adding the wash water to the system, identifying plants that add value to the system and increasing loading of the system to allow for larger scale use.

Mike Monnin (NRCS) asked why the process begins in an anaerobic digester.  Martin replied that the high carbon concentration (BOD-biological oxygen demand) needs to be reduced at the beginning so that denitrification and re-nitrification is not inhibited.

Lynn Willett (OSU) asked if BOD or COD (chemical oxygen demand) was measured.  Martin responded that BOD was monitored as the process is less time consuming; however, he is willing to discuss monitoring COD if there are benefits to doing so.

Fred Michel (OSU) asked how much methane was produced in the anaerobic digester.  Martin noted that the amount has not been quantified as yet.

Diane Borger (OSU) questioned the selection process for plant materials in the open aerobic reactor.  Martin replied that a good root environment is needed to sustain the microbes that degrade the nutrients.  Thus plants that continue to grow root mass even with high nutrient concentrations were used.  These plants had been identified in other systems.  Additional research is needed to identify plants that could have on-farm uses such as silage.

Maurice Watson (OSU) asked if solids accumulated in the system.  Martin noted that the solids that accumulated were about 20% less than found in conventional treatment systems.  He speculated that the roots may trap the sediments.

John Smith (OSU) asked how long the plants survive in the system.  Martin noted that the amount of nutrients assimilated by the plant is less than 2% of the material in the system as their main role is to provide an ecosystem for the microbes.  In the Waterman study, tropical plants were used and did not survive winter temperatures as there was no additional heat added to the greenhouse.

Kip Gardner (OSU) asked if the methane generated in the anaerobic digester could be used for heating.  Martin responded that the digester used was low tech and did not provide enough methane for heating.  Gardner suggested that a pond system could work.

A Columbus participant asked what total percentage of wash water from the Waterman farm was treated in this system.  Answer: about 5%.

Smith suggested that Martin contact Bill Bickert at Michigan State University.  Bickert has been working on a new style digester at Green Meadows Farm that moves the liquid through more quickly, increasing the methane produced.

Richard Moore (OSU) asked if an Amish dairy farm with about 30 cows could use the system and noted that some have access to free gas that could be used for heat.  Martin responded that the current system could probably be used for 30-40 cows as the four replications would not be needed.  As to the gas, the preference is to use the outputs of the system to provide heat.

Watson asked is artificial light is used in the greenhouse.  Martin noted that the only light used is if work needs to be done at night; it is not used for growing purposes.

Gardner asked if the effect of the system on viruses had been studied.  Martin replied that only coliform bacteria had been analyzed.  Future plans are to evaluate the effect on salmonella.

Gardner asked about Ohio impediments to permitting the treatment system.  Martin noted that the OEPA would be responsible for regulation.  Data indicating that the discharge meets or exceeds water quality standards would be required if there is a discharge.  Permitting is not required if there is zero discharge from the system which may be attained by using the treated liquids in a greenhouse or for irrigation.

Tom Noyes (OSU) asked for a clarification of the wash water being treated.  Is it from the milking house or the barn?  Martin noted that it is from the tie barn and includes the manure as well as  sawdust used for bedding.  These materials are flushed into the pit during cleaning.

Michel asked how more nitrogen could be used by the vegetation to increase yield.  Martin responded that it depends on the vegetation.  He currently is not familiar with any that would “hyper-accumulate” nitrogen.

Ted Short (OSU) noted that the air temperature in the greenhouse can affect the vegetation but suggested that the water temperature also be monitored and controlled.

Willett asked if the mass of manure needed to yield the necessary methane to maintain temperatures had been determined.  Martin responded that it has not yet been evaluated and noted that the optimal temperature for the greenhouse is 45-50o F.

Michel questioned a diagram showing the loss of ammonia and appearance of nitrate.  Why does nitrate not accumulate in the first few tanks?  Martin replied that in the first tanks, nitrification is quickly followed by denitrification due to the low oxygen levels in those tanks.

Willet asked about the pH of the system.  Martin responded that it is approximately 7 with little variation.

Larry Brown (OSU) questioned how the dairy staff perceived the impact of the system on dairy operations.  Martin noted that he thought there was little impact, but had not had feedback from them.  The dairy staff was not involved in collecting the wash water from the pit or operating the system in any way.

Brown suggested a demonstration test plot using the wash water for drip irrigation.  Martin noted that the wash water collected in the pit is usually disposed/treated via the sanitary sewers.

Martin commented on Ann Christy’s research using manure in a microbial fuel cell to generate electricity.  It may be possible to use this electricity to power the blowers used to aerate the tanks and the airlift pumps that move water between tanks, thus decreasing energy inputs from outside sources.

Monnin asked if the treatment system could work for smaller farms that have a more solid manure or for milkhouse wash water which has a high BOD plus some detergents and disinfectants.  Martin responded that it could work, especially if settling to decrease the solid content was the first step.  Research on municipal treatment systems indicated that ecological systems are fairly resilient; the key is biodiversity of microbes to allow adjustment to system inputs.

Tom Zimmerman (ATI), citing a study he conducted 10 years ago, used wetlands to treat dairy milkhouse wash water.  The raw wash water had a BOD of 1500 ppm and included some acids.  Martin replied that it is a high BOD and would need to be tested.  He will have a class this year that will evaluate the effect of adding acid to the manure treatment system.

Compost Dairy Barns in Minnesota
Dr. Marcia Endres, University of Minnesota

Compost dairy barns offer an alternative to handling dairy manure as a solid rather than a liquid.  Although often compared to older bedded pack systems, the compost dairy barns have two significant modifications:  1) use of sawdust as bedding and 2) increased ventilation.  Although the barn designs vary, they share several features, including bedded pack on a clay base, 4-foot perimeter wall surrounding the pack, two or more walkways for cows and equipment to enter the pack from the feed alley.  Water troughs are in different locations but designed to keep water away from the pack.  The concrete feed alleys may be in the center or outside lane and are scraped twice each day.  Management of the pack includes maintaining a depth of 4 feet of sawdust or fine wood shavings, with additions every 2-5 weeks, and aerating the top 8-10 inches twice daily. The bedding is removed yearly, usually in the fall, and land applied or further composted.

A 2005 University of Minnesota field study evaluated the impact of the 12 different compost barns on cow comfort, health and performance. Although the top layer of pack was biologically active, the temperatures were elevated only slightly, indicating minimal composting activity.  Somatic cell counts in milk were highly variable between farms but compared favorably to the Dairy Herd Improvement Association (DHIA).  Mastitis infection rates dropped significantly for 6 of the 9 herds that changed from traditional facilities to the compost barn.  Researchers noted that excellent cow prep at milking time, management of the barn and cow cleanliness are key to maintaining good milk quality and udder health.  The average pack area per cow in the study (90.2 sq-ft) was higher than the recommended 80-85 sq-ft/cow and possibly had a positive effect on cow social behavior.  In addition, the prevalence of hock lesions and lameness was lower than in other systems.  In general, the producers were satisfied with the system, including reduced management time, with the only concerns being the dust when replacing the pack and the cost and availability of sawdust for bedding.  A pilot study is underway to evaluate the effectiveness of other materials as bedding options.

Additional Resources:  UM Compost Dairy Barns website 

Dr. Keener (OSU), referring to reduction in somatic cell counts, asked if all the herds had previously been housed in tie-stall barns.  Endres replied that all but one herd had previously been housed in tie-stall barns, with only one coming from a free-stall barn. That farm had both a free-stall and compost barn with separate bulk tanks for a period of time, allowing direct comparison of somatic cell counts for the systems. The compost barn had consistently lower counts.

Brian Gwin (Wayne Economic Development Council) asked about the design and orientation of the barns with respect to air flow.  Endres reported that most were oriented east to west and some had 5-ft overhangs to minimize rain on the pack.  While most had 14-16-ft sidewalls, some were only 12-ft high and ventilation was not as effective.

Harry Hoitink (OSU) suggested that the high temperatures recommended for most composting are not needed for this type of system as it may contribute to high ammonia levels.  He suggested aerating more frequently and determining which management methods result in the healthiest cows, then evaluate what is happening biologically.

Mike Klingman (OSU) asked if there were issues with cows choosing different areas.  Endres noted that the choice seems to be where not to lie down, particularly to avoid of cow pies.

Web link question:  How much bedding is needed on a per cow per day basis?  It is approximately 30 lbs/cow/day.

Mike Monnin (USDA-NRCS) asked if the density of cows would need to change for Ohio which has a warmer climate.  Recommendations are currently 90-100 sq-ft/cow which is more than the 80-90 sq-ft/cow recommended for the compost barn.  Endres responded that the effects of density in Minnesota were based on observation not research criteria, but did note that the summer of 2006, during the study, was unusually hot with temperatures in the 90’s (0F).

Keener asked if udder injury had been observed as that was a common problem in older bedded pack systems which recommended 70 sq-ft/cow.  Endres noted that it was not a problem and suggested that it may have been the result of more space. 

Gwin asked if the area per cow included the feed area.  No, only the bedded pack area.

Hoitink asked if any of the manure from the feed alley is composted and how many farms are composting the pack that is removed.  Endres was not aware of any composting the manure from the feed alley, but a couple are composting the pack and selling it to garden centers.

Hoitink noted that if the sawdust has been composted less than 100 days, it should not be spread on the fields as it will increase the risk of nitrogen immobilization, although the timing may vary with particle size.  Endres noted that the first farm, built in 2001, has reported increased yields although they may be waiting before application.