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Washington State University Dairy News

June 2015 WSU Dairy Newsletter

Cool Temperatures and Large Particle Solids Affect Ammonia Emissions from Land Applied Dairy Manure

We have been studying the factors affecting the emission of ammonia from dairy manure for the past eight years. The major factors that affect ammonia emission at the time of application appear to be: the ambient temperature, manure treatment (anaerobic digestion of manure), large particle solids, and incorporation.

During the summers of 2010, 2011 and 2012 we conducted twenty-two manure application studies looking at the effect that various types of dairy manure had on ammonia emissions when applied to grass which was to be harvested as silage. In particular, we wanted to understand the impact that anaerobic digestion and large particle manure solids had on ammonia emissions. Figure 1 shows the typical pattern of ammonia concentration throughout the day of manure application.

Graph showing NH3 emissions by time of day following application.
Figure 1. Typical NH3 measurement on day of manure application.

Due to the cooler climate of the Pacific Northwest, it is common to apply manure at ambient temperatures below 60 degrees Fahrenheit. We found the that 60 degrees Fahrenheit was a critical temperature as we were not able to observe ammonia emissions on the day of manure application when it was cooler than 60 degrees.

We know from studies with anaerobic digestion (AD) of dairy manure that the amount of ammoniacal nitrogen can be greater in AD manure. This is due to the conversion of organic-nitrogen to ammonia-nitrogen by microbes in the anaerobic digester. This observation led us to assume that AD manure would lose more ammonia when land applied, when compared to non-AD (or raw manure). What we found in 2010 was that since AD manure had the large particle solids removed prior to storage, the AD manure actually had less ammonia emitted after land application than non-AD manure with large particle solids (see Figure 2). The reduced NH3 losses from liquid manure without large particle solids was due to the promotion of manure infiltration into the soil, consequently reducing the manure exposure time on the ground surface.

In 2011, we added an additional manure type, non-AD with large particle solids removed. When this manure type was compared to AD manure, and non-AD manure with solids, it was clear the effect that manure solids have on increasing ammonia emissions. Our data suggest that the ammonia emission were reduced by ~40% (see figure 2) when large particle solids had been removed.

Bar graph showing ~40% increase in ammonia emissions when large particle solids are not removed from manure.
Figure 2. Average ammonia concentrations for manure treatments, ADWOS = anaerobically digested manure without large particle solids, NADWOS = non-AD manure without large particle solids, and NADWS = non-AD manure with large particle solids.

Complete data published in Sun, F., J. H. Harrison, P. Ndegwa, and K. Johnson. 2014. Effect of manure treatment on ammonia and greenhouse gas emissions following surface application. Water, Air, and Soil Pollution. DOI 10.1007/s11270-014-1923-z

Joe Harrison, Livestock Nutrient Management Specialist, WSU Puyallup,

Amber’s Top Ten Tips: Understanding Heat Stress

Heat stress is bad news for dairy cows. We often hear about abnormal heat waves that roll through regions leaving behind millions of dollars of damage, but what about the losses incurred during a typical summer? Across the U.S., the economic losses attributed to heat stress are approximately $100 per cow per year. With summer knocking at our door, have you considered how hot weather impacts the cows on your dairy?

Interesting facts about heat stress in dairy cows:

  1. Temperature-humidity Index (THI)

    THI is commonly used to gauge the severity of heat stress dairy cows experience under specific environmental conditions (ambient temperature and relative humidity). THI ≥ 72 is categorized as heat stress; however, recent research has indicated that the heat stress threshold should be lowered to a THI of 68.

    THI = ambient temperature – [0.55 – (0.55 * relative humidity/100)] * (ambient temperature – 58.8)

    Ambient temperature is recorded in Fahrenheit and relative humidity is recorded as a percentage.

  2. Core Body Temperature

    As THI increases and, subsequently, core body temperatures increase, cows spend more time standing rather than lying down. Cows with rectal body temperatures ≥ 102.2°F (measured in the afternoon) are at risk for decreases in milk production and fertility.

  3. Water Intake

    Cows will consume 35 – 50% more water during heat stress conditions. Ensure cows have access to an adequate supply of clean, fresh water.

  4. Feed Intake

    Heat stress causes decreases in feed intake during the daytime, decreases in feed efficiency, and decreases in nutrient absorption. Nighttime “slug feeding” may lead to higher incidences of acidosis.

  5. Milk Composition

    Cow exposure to environmental heat stress has been linked to higher milk somatic cell counts and bacterial counts, with lower milk fat and protein percentages.

  6. Cooling Strategies

    Natural ventilation, fans, sprinklers/misters, shade access (esp. open lot dairies), and cooling pads all offer heat stress abatement for dairy cows; however, each dairy needs to assess which strategy will work best for each facility. Adjustments to feeding schedules, ration formulations, and stocking densities may also assist with heat stress abatement.

  7. Milk Production

    Depending on the severity of heat stress conditions, cows will decrease their milk production by 10 – 50%.

  8. Reproduction

    Conception rates during heat stress can plummet by almost 20%. For example, a dairy with a typical conception rate of 31% fell to a conception rate of only 12% during hot weather.

  9. Health

    Higher incidences of mastitis, respiratory problems, retained placentas, and higher respiration rates have been diagnosed in cows under heat stress conditions.

  10. Gestation

    Calves exposed to heat stress during the last 45 days of gestation have lower birth weights, lower weaning weights, and depressed immune systems.

Table showing onset of heat stress symptoms at various combinations of temperature and humidity.
Source: Zimbleman and Collier.

V.S. is No B.S.!

On May 29, Dr. Keith Roehr presented a webinar about the 2014 Vesicular Stomatitis (VS) outbreak in Colorado. Dr. Roehr is the Colorado State Veterinarian. He reported that between July 4, 2014 and Jan. 29, 2015, his office made 556 investigations and ultimately quarantined 370 premises that tested positive for VS. The late onset of Colorado’s winter in 2014-15 was blamed for such an extended outbreak duration.

What is VS?

VS is a contagious viral disease of all hoofed animals—particularly equines, swine and cattle; sheep, goats and camelids are affected less often. The virus occasionally spreads to humans and causes a flu-like disease and blisters in rare instances. It is believed to enter a herd via insect vectors (black flies, midges, sand flies, etc.) and then spread primarily through additional insect activity within the herd. Little transmission is believed due to direct livestock contact, animal movement, and mechanical means, such as contaminated equipment and facilities.

Signs of Illness

Cow showing erosions and sloughing of tissue on the lips and tongue.
Photo by Dr. Jeanne Rankin (from
Affected animals have erosions and sloughing of tissue on the lips, tongue (see photo), teats, prepuce, between the toes, and on hoof coronary bands. Blisters and vesicles occur on these areas early in the course of disease but are often missed by human caretakers. Other signs include fever, poor appetite, lethargy, weight loss, drooling, scabbed lesions, and lameness if feet are involved.

Why is VS Important?

VS is present in the U.S. and occasional disease outbreaks occur. Also, although VS is very contagious and can cause many cases of illness on premises, animals rarely die from it. Nevertheless, the disease is particularly important for several reasons:

  • The signs of VS are similar to three foreign animal diseases not present in the U.S.: foot and mouth disease, swine vesicular disease, and vesicular exanthema of swine. It is essential to differentiate VS from these other diseases quickly so the entry of one of these exotic diseases can be identified and dealt with promptly.
  • VS is infectious—outbreaks in the U.S. restrict some international trade until the outbreak is contained.
  • Its similarity to important foreign animal diseases make VS a reportable disease in the U.S.
  • Animals afflicted with VS are in pain, stop eating, lose weight and produce less milk. A widespread outbreak could cause significant animal suffering and economic losses. Dr. Roehr shared that economic losses of dairy farms involved in the Colorado outbreak were over $1M on some farms when decreased production, increased labor, reduced livestock marketing options, diagnosis and treatment costs were considered.

Control Measures

A vaccine for VS is not available in the U.S., so control of biting insects is the major component of VS control and prevention:

  1. Reduce exposure to flies by reducing pasture time.
  2. Eliminate stagnant water or keep livestock away from wet areas where insects of concern are more common.
  3. Use effective approved insect repellents.

To reduce mechanical transmission of the virus, equipment and tools should not be shared between farms. During outbreaks, healthy animals should be monitored closely for early signs of illness (fevers and vesicles) so they can be isolated from other animals quickly.

State and/or federal veterinarians are responsible for making the diagnostic determination in cases of VS. They issue quarantine orders, stopping animal movement to and from affected premises. They also advise owners about disinfection measures and isolation of affected animals to protect unaffected animals on the premise.


VS outbreaks are a reminder for livestock owners to develop, fine tune, or brush the dust off farm biosecurity plans. Livestock owners will be the first line of defense in the event of the entry of a foreign animal disease into the U.S. Early detection is our best hope for containing economically-important diseases such and foot and mouth disease. Monitor your animals regularly for signs of illness and call your veterinarian immediately if you see vesicles, blisters, erosions, or the other signs previously mentioned. Let’s hope it is “only” VS or something more innocuous.

A recording of Dr. Roehr’s webinar is available from Iowa State University Extension and Outreach. He discusses dairy cattle involvement in depth.

For Additional Information

LIVESTOCK OWNERS: If you ever notice a vesicle, blister, ulcer or erosion on an animal’s mouth, teats, prepuce or feet, contact a veterinarian at once. Odds are this is not a foreign animal disease, but if it is, every hour of diagnostic and containment delay means an exponential increase in the cost of the outbreak, in both economic impact and animal suffering.

December 2014 WSU Dairy Newsletter

Greetings and Welcome to Our New Look for the WSU Dairy Newsletter

With this issue of the WSU Dairy Newsletter, we debut a new system for managing our Newsletter. Please provide any feedback in regard to the format and usefulness of this publication to Joe Harrison at

Dr. Amber Adams-Progar
Dr. Amber Adams-Progar
In addition to the change in the Newsletter format, we would also like to welcome Dr. Amber Adams-Progar, Dairy Extension-Research faculty in the Department of Animal Sciences at WSU Pullman. Amber joined the faculty in June of 2014 and will focus on Animal Well-Being and Calf Management, as well as being a resource for general dairy extension needs in the state. She can be contacted at or 509-335-0673.

Dr Amber Adams-Progar’s Top Ten Tips: Calf Management

After spending the last year and a half working with about 40 dairy farms, and putting over 60,000 miles on the rental car, I have seen a wide variety of calf management strategies. Some ideas were instant successes, some were close to success, and others just flat out failed. When evaluating your calf management practices, keep these 10 things (listed in no particular order) in mind:

  1. Calving area

    Avoid housing sick cows in the calving pen and keep the calving area as clean as possible to limit a newborn calf’s exposure to pathogens.

  2. Location, location, location

    Prevent the transmission of disease from older cattle to calves by housing calves away from older cattle and removing nose-to-nose contact between the two age groups.

  3. Cleanliness of calf environment

    Cleaning the pen/hutch and buckets after each calf decreases bacteria exposure from calf to calf.

  4. Bedding

    Choose bedding that keeps calves clean, but doesn’t irritate the respiratory system.

  5. Ventilation

    Remember to test airflow at calf height and prevent drafty areas that may cause a calf to become chilled.

  6. Water

    Access to clean water during the day improves calf gain and reduces the effects of heat stress.

  7. Nutrition

    Providing sufficient amounts of milk and starter feed that are free of pests, including flies, promotes higher feed intake and better health.

  8. Lighting

    Ensure the natural or artificial lighting is plentiful so calf care managers can easily observe calves for signs of illness.

  9. Colostrum

    Quality of the colostrum should be measured using a Colostrometer or Brix refractometer for assurance that the calf will receive adequate immunity.

  10. Health records

    Maintaining calf treatment records reduces errors in treating calves and reveals calf disease patterns that can be addressed with your veterinarian.

Feeding Pasteurized Waste Milk to Calves

If you have a steady supply of waste milk, you might consider pasteurizing and feeding it to calves. Many studies show this can result in cost savings, improved calf health and increased growth rates.

Definition of Waste Milk

Waste milk includes colostrum, transition milk, high cell count milk, milk withheld due to antibiotic treatment and mastitic milk. It isn’t recommended to feed raw or pasteurized milk that is overtly abnormal or milk with extremely high bacterial loads. Also, because of the possibility of antibiotic residues in waste milk from treated cows, it shouldn’t be fed to animals being raised for meat; this possibility might also discourage some producers from even feeding it to replacement heifers.

Hows and Whys

Milk replacer costs continue to rise and it is not cost-effective to feed salable milk to calves when milk prices are high. Feeding waste milk can meet calves’ nutritional needs by using an otherwise-discarded product. Feeding raw waste milk is not recommended due to its potential to contain a variety of disease-causing organisms (see box).

Pathogens of Concern in Raw Milk

  • Mycobacterium avium subsp. paratuberculosis
  • Salmonella species
  • Mycoplasma species
  • Listeria monocytogenes
  • Campylobacter species
  • Mycobacterium bovis
  • Enterobacter species
  • Staphylococcus species
  • E. coli

Pasteurized waste milk (PWM) greatly reduces the pathogen load to which calves are exposed, but not to the complete reduction achieved through the use of well-managed milk replacers. Growth rates on PWM exceed those of traditional milk replacers but are similar to those of new higher-quality milk replacers. The table below compares the nutritional content of milk, waste milk and milk replacers on a dry matter basis.

Nutritional content of milk, waste milk and milk replacers on a dry matter basis
Source Protein Fat
Milk 24 to 27% 28 to 36%
Waste milk 25 to 30% 25 to 35%
Milk replacer 18 to 29% 15 to 20%

Economic analyses found that feeding PWM was cost effective when at least 23 calves were fed in one study and 60 in another. This indicates that PWM feeding is probably not cost effective for smaller operations.

It is recommended to collect and store waste milk in a dedicated bulk tank so the pooled milk can make the nutritional content more uniform and dilute any milk containing antibiotics. Waste milk should be cooled to at least 45°F before and after pasteurization and protected from contamination after pasteurization. This bulk tank should be cleaned and sanitized just like the salable milk tank.

Advantages and Disadvantages

Overview of the potential advantages and disadvantages of feeding PWM to calves.
Advantages Disadvantages
  • Probable feed cost savings, especially in comparison to high quality commercial milk replacers.
  • Compared to raw milk, improved calf health (especially scours and pneumonia) due to reduced exposure to disease-causing agents.
  • Faster growth due to higher nutritional content of waste milk vs. most milk replacers.
  • Effective pasteurization kills up to 99% of bacteria and deactivates toxins
  • Beneficial use of otherwise-discarded products.
  • Various immune factors in whole milk may survive pasteurization and provide protection not available via milk replacer.
  • Cost of pasteurizer and energy to operate it.
  • Increased trained labor for managing, monitoring and cleaning pasteurizer (if not self cleaning).
  • Need to cool and store milk ASAP before and after pasteurization.
  • Dependence on regular volume of useable waste milk.
  • Pasteurization process can fail so must be monitored routinely.
  • Variable nutritional content of batches, especially in small herds.
  • Potential feeding of low-level antibiotics to calves.

Pasteurization Options

Most pasteurizers are either standard batch pasteurizers (commercial or homemade) or commercial high temperature/short time (HTST) continuous-flow machines. Batch units heat a batch of milk to 145°F for 30 min.; the milk is cooled and fed. In HTST systems, milk is rapidly heated to 161°F for 15 sec., then cooled to be fed or held. These units pasteurize milk more quickly, thoroughly and dependably than batch systems, but they are harder to clean unless automated. The price of commercial units continues to drop with increasing acceptance on farms. Colostrum can be pasteurized, but it must be done at a lower temperature for a longer time so immunoglobulins essential for neonatal calf health will not be destroyed; 140°F for 60 min. is recommended.

Conclusions, Problem Solving and Cautions

As you can see, each farm needs to weigh the pros and cons of feeding milk replacer, raw waste milk, salable raw milk or PWM to calves. The ultimate decision is a balance between disease control, feed costs and labor; this decision can fluctuate with market price changes. Here is a summary of suggestions and considerations regarding the feeding of PWM:

  • Do not use heavily contaminated waste milk or visibly mastitic milk for calves.
  • Wait to feed PWM until calves are over one day old.
  • Avoid switching calves between PWM and milk replacer. Estimate expected upcoming waste milk volumes and assign calves to either PWM or milk replacer feeding if there isn’t enough PWN for all. If calves must be switched, try to do so after calves are at least three weeks old.
  • If waste milk volume is low, high somatic cell count milk could be included.
  • Don’t collect milking system flush water with waste milk to be fed to calves; this will dilute milk nutrients excessively.
  • Do not consider pasteurization a shortcut to sanitation, milk handling and best feeding practices. All milk feeding equipment (buckets, bottles, nipples, etc.) still need to be cleaned and sanitized or the disease-reduction benefits of pasteurization will be lost.
  • Agitate and mix stored batches close to feeding time or fat will separate from milk, causing some calves to receive too little fat and others too much.
  • Because pasteurization greatly reduces pathogen loads in milk but does not sterilize it, it is still recommended to house calves individually to prevent suckling and possible disease transmission.
  • Employee training and understanding of pasteurization is essential.
  • Routinely monitor the pasteurization process through temperature checks and milk cultures for quality testing (goal: standard plate count <20,000 cfu/ml).
  • Reminder: calves fed PWM.
  • may ingest antibiotics in milk from treated cows, so withholding periods must be observed.
  • Suggestion: visit with producers who are successful with waste milk pasteurization systems to observe the process, ask questions and learn from their experience.


On a related note, a spreadsheet that helps decide when it is more cost effective to feed milk replacer vs. salable whole milk is available from Penn State Extension. If you do not have access to the internet, contact me and I’ll be happy to work through the spreadsheet with you.

Useful links for additional information

Western Dairy Management Conference

March 3 – March 5, 2015 | Reno, NV

John Ascuaga’s Nugget
1100 Nugget Avenue
Reno, NV 89431

Conference Schedule


  • Tuesday, March 3: 10:00 AM – 5:30 PM
  • Wednesday, March 4 & Thursday, March 5: 6:30 AM to 5:00 PM

Seminar Schedule

  • Tuesday, March 3: 1:30 PM – 5:30 PM
  • Wednesday, March 4 & Thursday, March 5: 8:00 AM – 5:40 PM

Opening Reception

  • Tuesday, March 3: 5:30 PM – 7:00 PM


Go to the Western Dairy Management Conference website and complete your registration online. You can also register by mail. Complete and return the attached registration form (one form PER PERSON) along with payment. The conference fee is $390 per person if postmarked by February 1, 2015.

After February 1 the registration fee is $425. Student Registration is $200.

Waste to Worth 2015

March 30 – April 3, 2015 | Seattle, WA

You are invited to attend the International Conference on Livestock & Poultry Environmental Quality

A national network of agri-professionals addressing issues related to air, water, soil, and climate.

Details on registration, hotel accommodations, sponsorship, vendor display registration, program, and tours a the Waste to Worth conference website.

Who should attend?

  • Extension agents & specialists
  • Farmers & producers
  • NRCS staff
  • Technical service providers
  • Consultants
  • Regulatory & policy advisors
  • Commodity groups
  • Environmental NGOs
  • Technology providers
  • Researchers
  • Vendors