NDSU Extension Service
North Dakota State University

Vol. 15, No. 2     May 2005



     Insect control
     Calculating dilutions for footbaths 

     Too much "dairy character"
     Rules for living with bulls 

     Rumensin -A tool, not magic
     What are the risks? 

     Ag labor management 

     The basics of forage testing insert

     Milking producer can improve milk quality insert
     When to forestrip?
     PI test - what is it?
     Drainage important to cleaning insert

     Things Mom wouldn't say 




Well, it's spring, or is it fall? No, it feels like winter, but that's spring in the northern Great Plains. Regardless, the busy month of June is next on the calendar. June is Dairy Month, Make Forage Month, Clean Lots Month ... and the list goes on!

Plans are being finalized for a "day on the farm" Saturday, July 9. Destiny Dairy (the Ole and Jessica Johnson family) is working with the North Dakota Dairy Coalition to provide folks in the region with an opportunity to see a working dairy operation. While this is nothing new to this audience, the opportunity is highly valuable to the rest of the world (at least our small part of it) that enjoys dairy products but no longer knows where they come from. So put the date on your calendar and encourage others to catch a ride to Destiny Dairy. Lunch will be provided.

With this edition of Dairy Connection, I have attempted to provide you with timely topics pertinent to your dairy operation.

Have a great summer.

J.W. Schroeder
Extension dairy specialist
Department of Animal and Range Sciences




Insect control

It's never too early to initiate preventive measures to control pesky farm insects. With warm and humid conditions soon here, combined with the organic matter accumulation in the barnyard, manure is the perfect breeding ground for flies.

The reasons for control are many. However, preventing disease is particularly important this time of year. Flies are a good vector for the spread of diseases such as pink eye and Staph Aureus mastitis. Heifers are extremely susceptible to these diseases, as more often than not, they are not being checked every day. By reducing the fly population on your farm, you can prevent blind eyes and the spread of contagious mastitis to your herd. Now is the ideal time to start your entire herd on a pour-on fly control product. These products provide the best solution to the fly problem, and in addition, they can provide protection against worms and eradicate lice.

Fly tags alone are not sufficient for reducing fly populations, as research has shown an increase in resistance to organophosphates and pyrethrum because of the slow, constant release of these compounds. Furthermore, fly tags do nothing to control flies biting udders. Pour-on control needs to be applied to all animals, including wet calves. It should continue every four to six weeks to be effective. Rotate products at least yearly, if not twice a year. Rotate active ingredients, not name brands since name brands can have the same active ingredients. In addition to pour-on fly control, consider other management practices.

First, make sure you maintain your facility and minimize areas where manure and other organic material can accumulate. Second, consider feeding the whole herd an oral larvacide, which will control juvenile fly populations and reduce overall loading. All the pour-on and spray will not be effective if you have another generation of flies hatching daily. Lastly, keep good records. Record what product you used and when you used it. Keep track of mastitis, pink eye and other health issues to enable your herd veterinarian or Extension Service agent to help pinpoint problem areas. By starting now, you too can help reduce (sorry, not eradicate!) the fly population on the farm.

Calculating dilutions for footbaths

Foot ailments are especially common in confinement. Their occurrence has tremendous negative economic impacts. Footbaths have been used to control foot problems for many years with moderate success.

A proper dilution of compounds probably is the most important factor. Too high concentrations of footbath compounds waste money and can harm cows. Footbath solutions that are too weak usually are ineffective.

Here are the steps for establishing the required dilution:

1. Calculate the volume of the tub that will hold the solution.

If you are working with square or rectangular tubs, you can use the following formula to determine the volume of solution in gallons a tub will hold:

- Length (in feet) times width (in feet) times 7.46 equals volume in gallons.

For example, to calculate the number of gallons of water in a footbath 6 feet long by 3 feet wide and 6 inches deep, you would multiply 6 by 3 by 0.5 (½ foot deep) by 7.46 to get 67 gallons.

2. Check for the measurements in which the footbath is presented.

Many products used in footbaths are in metric terms. Therefore, you must convert gallons to liters. Since 3.8 liters equal 1 gallon, all you need to do to determine the total number of liters in the above example is simply multiply the total number of gallons by 3.8 (67 gallons x 3.8 equals 255 liters).

3. Calculate the footbath solution/concentration.

For example, we want to prepare a footbath solution containing a 1-gram-per-liter concentration of some compound. If we add 100 grams of this compound to 255 liters of footbath solution, the concentration of this compound in the foot bath is 1 gram per 2.55 liters. This does not achieve our objective. However, if we add another 155 grams of this compound to the solution, we achieve a 1-gram-per-liter concentration (255 grams in 255 liters).

This is logical, right? However, the process is more difficult if these concentrations are listed in milligrams per milliliter (mg/ml), rather than grams per liter.

Consider these relationships:

1 liter = 1,000 milliliters (ml) and 1 gram = 1,000 milligrams (mg).

Of we add 1 gram of a compound to 1 liter of solution, we end up with a 1-gram-per-liter concentration of that compound in the solution. Assuming that this compound is dissolved freely and distributed in the solution, there is 1 mg of compound in every 1 ml of this solution. In other words: 1 gram/liter is equivalent to 1 mg/ml.

If possible, convert your compound (active ingredients) into grams, and try to keep concentrations in grams per liter. Finally, don't be afraid to ask your veterinarian, nutritionist or other person experienced with doing dilutions in metric terms for help.

The following are dilution rates for commonly used foot-bathing agents:

• Copper sulfate

5 percent - requires 8 pounds of copper sulfate in 20 gallons of water

10 percent - requires 16 pounds of copper sulfate in 20 gallons of water

•Zinc sulfate

20 percent - requires 34 pounds of agricultural grade zinc sulfate monohydrate (36 percent) in 20 gallons of water


0.1 percent - requires 4 grams of tetracycline in 25 gallons of water



Too much "dairy character"

The trait called "dairy character" or "dairy form" is losing its luster in genetic selection indexes. Research has shown that cows that lose a lot of weight after calving to support high milk production tend to have greater health and fertility problems. Such cows cannot meet their energy requirements from the feed they eat, and they mobilize stored body energy, fat mostly, to meet the deficit.

For many years, one of the "holy grails" of dairy cattle breeding was the high-producing, very clean, nonfleshy dairy cow. Looking back on that era, I recall the doubts that many (me included) had about high-milk records on cows with substantial amounts of body tissue - muscle and fat reserves - across the withers, down the topline and in the seat of the pants. "Fat" cows got that way because they used feed for body fat instead of milk. Certainly, the dairy population had cows like that 30 and 40 years ago, but it's a different story today.

The genes for production are in our dairy cows, but we haven't tried to control whether the energy to make that milk came from feed consumed or body fat. Recent changes to the TPI formula put negative weight on dairy form, favoring a slightly less "dairy" cow.

Really good work has been done in Scotland in recent years on energy balance in selection (for fat plus protein) and control, such as Holstein's on high- and low-concentrate diets. That project had several objectives, but the conclusions of a recent paper (J. Dairy Sci 87:4318) included this statement: "Selection primarily for yield, perhaps exacerbated by additional selection for angularity (or dairy form), has led to cows that mobilize more of their body energy in early lactation and do not replenish all lost body lipid later in their productive life." Some measure of changes in body energy during peak production periods could well be part of future selection indexes.

The search for the cow with the ability to maintain body condition under the energy demands of high production through feed consumed will be a tough nut to crack. We likely will not have feed intakes and changes in body weights on large numbers of daughters in progeny test programs. Indicator traits will be necessary. Dairy form is one such trait. The negative weight it receives in the new TPI reflects the findings of the Scottish study.

Source: B. Cassell, Extension dairy scientist, Genetics and Management, Virginia

Rules for living with bulls

If you are going to use bulls on the dairy farm, then everyone must know and adhere to these five rules, stresses Michael Overton, veterinarian at the University of California-Davis Veterinary Medicine Teaching and Research Center in Tulare. Failure to do so could lead to accidents or even loss of life.

1. Treat every bull as if he's a known killer, especially Jersey bulls.

2. Never turn your back on a bull.

3. Always have an escape plan in mind before entering a pen with a bull.

4. Look for and report to management any warning signs of aggression, such as pawing, head down or sideways stance.

5. Beef him at the first sign of a problem or at 2.5 years of age _ whichever comes first.

Source: Dairy Herd Management, April 2005




Rumensin - A tool, not magic

Last October, the federal Food and Drug Administration approved the use of the ionophore Rumensin in lactating and dry-dairy cattle diets. Many producers have used Rumensin in dairy heifers as an aid to controlling coccidiosis and for improved feed efficiency. However, it's now approved for use in the milking herd with claims for improved milk production efficiency.

Rumensin is an antibiotic that's not used in the human food industry. It alters fermentation of carbohydrates in the rumen by changing microbial populations, resulting in more glucose precursors (that's good for lactose production) and less waste gas production. Effective dairy managers should evaluate this new technology by weighing expected costs against expected benefits and estimating the likelihood that a beneficial response will be observed.

The good news is that including Rumensin in the ration costs pennies per day. Therefore, the amount of increased milk production necessary to generate a net positive return is small. Including Rumensin in the ration should result in an improvement in milk production of 1.8 percent to 3.9 percent. In addition, since it improves the cow's glucose production, it would be expected to lessen the risk of ketosis when fed to dry and transition cows.

What are the risks?

Rumensin has a very wide safety margin for humans and animals. Lowered milk fat percentage has been observed, particularly when effective fiber levels are marginal in the ration.

Nutritional management when Rumensin is included in the ration:

1. Include Rumensin in the ration at 11 gallons/ton of total ration dry matter to begin. This is equal to 5/.5 milligrams/pound of ration dry matter. Increases in feeding rates should be made only in consultation with a qualified nutritionist.

2. Feed Rumensin by adding it to a concentrate or mineral carrier mixture provided by your feed mill to assure accurate mixing. Feed this mixture as part of a total mixed ration. Feeding Rumensin in a concentrate mixture during milking or separate from a TMR is not approved at this time.

3. Rations must contain adequate effective fiber.

a. If the milk fat percentage is less than 3.5 percent for Holsteins, correct the fiber deficiencies before using Rumensin.

b. Rations should contain the following minimum levels of fiber:

i. 19 percent to 20 percent acid detergent fiber

ii. 29 percent to 30 percent neutral detergent fiber

iii. 21 percent NDF from forage

iv. 10 percent of the ration should reside on the top screen if the Penn State Particle Separator is used.

v. More than 50 percent of the cows should be chewing their cud when observed.

vi. If rations don't contain long forage, consider adding 1 to 2 pounds of ground straw per cow per day.

c. Consider using buffers, such as sodium bicarbonate, at a rate of .3 pound per day.

4. Give it time. Once Rumensin is added, keep it in the ration for at least one month before making a judgment on its efficacy in your herd.

Source: R. James, Extension dairy scientist, Virginia




Ag labor management

Looking for resources on agricultural labor management? A Web site that Gregorio Billikopf Encina manages for the University of California can help. He covers a variety of topics, in English and Spanish, from workplace violence to incentive pay to agriculture safety.

Check out the Web site at www.cnr.berkeley.edu/ucce50/ag-labor/ 




The basics of forage testing

Forages are arguably the most important ingredient in the dairy diet. Once forage supplies and forage nutrient analyses are determined, all other feeds can be programmed for the dairy herd. But testing takes time and quality changes on a daily basis in the field. With 2004 forage supplies dwindling and the 2005 harvest season under way, forage testing is the topic of the hour. The following are key concepts of forage and feed testing:

Collect a representative sample

To have an accurate forage test for ration formulation, having a representative sample is important. The method of sampling varies with forage type. Silages (corn or hay crop) can be sampled whether at harvest or at feed-out. The best method is to take three to four handfuls from every third load or more and place them in a container with all samples from the same field. Keep the samples covered to prevent drying. After mixing the composite, you can take a subsample for analysis (you need only a pint or 100 grams).

When sampling at feed-out, take three to four handfuls at different times, mix the composite and take a smaller subsample for analysis. Even if sampled at harvest, continue sampling and testing every four to six weeks during feeding.

When sampling hay, use a core sampler. Take 10 to 20 core samples from each hay lot, then composite and mix and take a subsample for analysis. Sample small rectangular bales by coring from the end. Sample large hay bales from the front or back (not the sides) to get a cross section of the rolled hay.

Wet chemistry vs. NIR

Forages are analyzed for nutrient content two ways. Wet chemistry uses established laboratory tests to quantify protein, fiber, fat and minerals. More recently, near infrared reflectance spectroscopy (NIR) has been perfected to quickly, economically and accurately measure nutrient content without destroying the sample. Also, NIR technology uses light reflectance and works best with large compounds, such as those that compose protein and fiber. The minerals are smaller and, therefore, more difficult to measure with the NIR, so use wet chemistry if you need precise levels. The NIR instrument must be calibrated to wet chemistry, which is the standard.

Most typical forages can be analyzed with NIR, but unique forages may not be appropriately analyzed because no calibration set is available to standardize the equipment. Also, total mixed rations are difficult with NIR because the composition of the mix can vary greatly from farm to farm.

Basic tests (wet chemistry)

When a forge testing lab receives a sample, a portion of it is weighed and dried in an oven to eliminate the moisture. It then is reweighed and the dry matter content determined. The dried sample then is ground for analysis. A portion of the sample is weighed into a tube for a Kjeldahl or nitrogen determination. Other methods can be used to determine nitrogen, but this is the most common.

The sample is digested with acid and then distilled with a base solution to convert nitrogen to ammonia, a form that can be trapped and analyzed. Nitrogen is converted to crude protein by multiplying by 6.25 because protein is 16 percent nitrogen (100/16=6.25). Crude protein measures all nitrogenous compounds present in the sample and does not distinguish true protein from nonprotein nitrogen. This is fine for ruminants (cattle, goats and sheep) but can be a concern for chickens and swine because they can't utilize nonprotein nitrogen.

Forage testing labs typically run two types of fiber determinations. These fibers are termed acid detergent fiber (ADF) and neutral detergent fiber (NDF). NDF is larger than ADF in plants and is considered to be the cell wall component. NDF is used to predict intake while ADF is used to predict digestibility. Both can be used to estimate energy.

Energy typically is not measured in forage testing labs. It is dynamic and, unlike protein or fiber, changes with animal physiological conditions. Energy can be estimated based on fiber content and an inverse relationship exists, with high fiber being associated with lower energy.

Many times different labs will report different estimates for energy because the equations they used are different. Energy usually is expressed as kilocalories (1,000 calories) or megacalories (1 million calories) of net, metabolizable or digestible energy. Also, total digestible nutrients, or TDN, an indicator of energy content. Generally, using conservative estimates for energy is best unless it is well-established that reported levels are acceptable.

Comparing the results

When expressing concentration of nutrients, define if the results are expressed on an actual ("as is" basis) or dry-matter basis. Nutrient concentrations expressed on an "as is" basis are less than when expressed as dry matter. The feed industry uses the "as is" basis to express nutrient concentration on feed tags. Therefore, producers must know what basis nutrients are expressed in before they can use the results. Crude protein, fiber, fat and macrominerals (calcium, phosphorus, etc.) usually are expressed as a percentage. However, microminerals (zinc, cobalt, etc.) usually are expressed in parts per million (ppm). Energy will be as a percentage of TDN or kilocalories or megacaloried per pound. Vitamins are expressed as international units of activity per pound. Therefore, what units will be used depends on the nutrient type.

Source: C. Stallings, Extension dairy scientist and coordinator of forage testing, Virginia Tech




Milking producer can improve milk quality

Making changes to milking procedures improves milk quality, according to participants in Wisconsin's Milk Money Program. Clean teats and a consistent procedure helped reduce both clinical and subclinical mastitis. If you are not using these practices already, give them a try. They do make a difference.

• Begin with calm cows. Stressed animals don't release milk as effectively as calm animals.

• Use latex gloves to reduce the spread of bacteria between animals and to protect milkers' skin.

• Forestrip to stimulate milk let-down and detect mastitis.

• Pre-dip with an iodine-based product.

• Clean and dry teats. Use a single-use paper or cloth towel to make sure teats are clean and dry.

• Two-minute goal. Attach all milking units within a minute or two of udder stimulation.

• Detach units with well-adjusted automatic take-offs for consistent take-offs and to reduce overmilking.

• Post-dip, completely covering the entire teat with a product proven effective at killing bacteria.

Source: M. Mahoney, Extension milk quality veterinarian, University of Wisconsin

When to forestrip?

A question often asked is "when should forestripping be done in the milking routine - before or after teat-end disinfection?"

When producers practice both pre-dipping and forestripping, no data indicates that the order in which the steps are performed will affect milk quality. On a practical basis, however, when teats are clean, forestripping before teat-end disinfection may be best to reduce the opportunity to re-contaminate the teat skin.

In milking parlors, cows can be forestripped onto the floor but producers should note the appearance of the milk to identify cows with mild cases of clinical mastitis. In stall barns, milk never should be forestripped onto cow beds. Milking staff should use gloves to reduce the potential of contaminated hands spreading mastitis pathogens.

Source: 2004 NMC Regional Meeting proceedings

PI test - what is it?

The preliminary incubation of the P.I. test was developed in the 1930s as an indicator of unsanitary conditions on dairy farms. The P.I. test indicates the presence of psychrotrophic bacteria, which primarily are made up of gram-negative bacteria (pseudomonas, some coliforms, flavobacterium and some alcaligenes), and are capable of growing at temperatures below 50 F.

The P.I. test is conducted by incubating the sample of raw milk at 55 F for 18 hours, and then a Standard Plate Count (SPC) is run. The pre-incubation allows psychrotrophic bacteria to grow until numbers are high enough for the SPC to detect them. A good (low) P.I. count is less than 10,000 cfu/ml; an acceptable level is less than 50,000 cfu/ml; and a count of more than 50,000 cfu/ml should be a concern.

To prevent a high P.I. count, maintain a good sanitation program for cows and milking equipment. This includes removing udder hair and using a sanitizing teat dip to prep cows for milking. All equipment, including the bulk tank, should be washed properly after each milking and sanitized prior to use. Inflations and milk hoses should be replaced at regular intervals, and the milk cooled to less than 40 F within two hours of milking.

A final place to check for high counts is your farm's water supply. By implementing a rigid sanitation program on your farm, you can improve your milk quality.

Source: A. Grove, Extension dairy agent, Virginia

Drainage important to cleaning

Improper drainage is a common source of bacterial contamination in milking systems. The pooling of fluids in the milking system also can lead to cleaning solutions mixing, which may reduce their effectiveness. All parts of the milking system (both sanitary and nonsanitary) should drain when the system is shut off. When troubleshooting cleaning problems, be sure to inspect the system for any pipes, hoses, fittings and equipment that do not drain after shutting down the system.

Source: NMC publication: Troubleshooting Cleaning Problems in Milking Systems




Things Mom wouldn't say


2. Yeah, I used to skip school a lot, too.

3. Just leave all the lights on - it makes the house look more cheery.

4. Let me smell that shirt. Yeah, it's good for another week.


6. Well, if Timmy's mom says it's OK, that's good enough for me.


8. I don't have a tissue with me - just use your sleeve.

9. Don't bother wearing a jacket; the wind-chill is bound to improve.

Author unknown

NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating. Duane Hauck, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, sex, disability, age, Vietnam era veterans status, or sexual orientation; and are an equal opportunity employer. This publication will be made available in alternative formats for people with disabilities upon request, 701/231-7881.

NDSU Extension Service
North Dakota State University