December 2001

2002 DHIA District Meetings Notice

All members are welcome to attend the District Meeting. If you are a member, you are eligible to vote. Agenda items will include a review of the audit for 2001, election of delegates to the Annual Meeting scheduled for March 26, election of directors for 3-year terms in districts noted below, and new and old business.

Tuesday	February 26	Southwest District at Orchid Inn, Sleepy Eye
Friday	March 1	Southeast District at the Branding Iron, Preston
Tuesday	March 5	South Central District at Diggers, Kasson
Tuesday	March 12	West Central District at Pizza Ranch, Glenwood
Thursday	March 14	Stearns District at the Lab in Sauk Centre

All meetings begin with registration at 11:15 with the meeting beginning at 11:30
Lunch is provided for members. More details will be in the January and February news.

Call 800-827-3442 for answers, or to make a reservation.

Percent of Daily Milk Shipped

The percent of daily milk shipped can be found in the "Daily Milk" section of your Herd Summary sheet. What is it? MN DHIA uses the last three bulk tank shipments and the current test day milk total to calculate % Milk Shipped. DHI MILK/Bulk tank milk. So if test day milk is greater than bulk tank average milk for the past three days, milk shipped will be over 100%. The national average for % milk shipped is 103%, accounting for kids, cats and calf milk that might be removed from the bulk tank.

Normal milk shipped is considered to be within +/- 7% of the normal 103%, or 95-110%. As of November 30, we have 3294 herds on test and only 66 herds have milk shipped outside of the normal percentage. Considering we use the previous 3 bulk tank weights and compare them to the current calculated test day milk, we feel this is a very low number of herds outside normal range.

For a number of years we have offered the service of helping correct milk shipped problems as they occur. The number of herds outside of the normal % milk shipped has been going down every since. If you have any questions or concerns about the accuracy of your test day results or bulk tank, please talk to your Field Representative or call Minnesota DHIA @ 1.800.827.3442.

Don't Waste Your Protein

Sandra Godden, College of Veterinary Medicine, University of Minnesota
Jim Linn, Department of Animal Science, University of Minnesota

Feeding excess protein to dairy cows is expensive and wasteful. Protein or nitrogen fed in excess of requirements for body maintenance, milk production, growth, and reproduction must be excreted. Excretion of excess nitrogen from the body means loss of income and is of environmental concern. Milk urea nitrogen (MUN) is an inexpensive and easily conducted test to help assess protein feeding to dairy cows.

WHERE MUN COMES FROM
The crude protein (CP) you feed your cows has three fates:

It can be broken down by the microorganisms in the rumen to ammonia.
It can bypass the rumen and be broken down into amino acids and absorbed from the small intestine.
It can bypass the cow entirely and be excreted in the manure.

Some of the ammonia released in the rumen from CP breakdown can be recaptured by the microorganisms to form bacterial CP. Bacterial CP then leaves the rumen and is digested in the small intestine, the same as the true proteins in feeds that bypass the rumen.

Ammonia not recaptured by the microorganisms is absorbed into the blood, where it is transported to the liver for conversion into urea. Amino acids and other small protein fractions absorbed from the small intestine in excess of requirements are also converted to urea in the liver. Urea is a nontoxic compound for handling excess nitrogen in the body until it can be filtered through the kidney and excreted in the urine.

Urea in the blood, referred to as blood urea nitrogen (BUN), also has three potential fates:

It can be recycled back to the rumen through saliva and directly through the rumen wall. Because urea is a relatively small molecule and has a high affinity for water, it rapidly flows back into the rumen, where it can be converted into microbial protein.
It can be removed by the kidney and excreted in the urine. The amount of nitrogen or urea in the urine is directly proportional to the concentration of BUN.
Because urea has a high affinity for water, as BUN passes through the mammary gland, it readily diffuses into milk to achieve an equal concentration of urea between blood and milk. Milk urea nitrogen (MUN) levels are similar to BUN levels, but usually lag behind peak BUN values by about two hours.

MEASURING MUN
Urea can be measured in either blood or milk. However, it's cheaper and easier to collect milk samples than blood samples. Milk samples may be submitted as bulk tank or individual cow samples. The difference is that a bulk tank sample doesn't allow for evaluation of groups fed different rations. Given the relatively low cost of analysis, we recommend that MUN be analyzed for individual cows. MUN may be measured in milk samples routinely collected on DHI test day. Test costs in Minnesota range from 11.5 to 15 cents per cow, depending on which lab you use and the test method used.

INTERPRETING MUN RESULTS
Because MUN levels are affected by a large number of cow-related factors, including age, stage of lactation, health status, water consumption, and dry matter intake, cows fed the same ration often have very different MUN values. For this reason, we recommend you use MUN results from a minimum of 10 cows for diagnosing potential feeding problems. Don't try to draw conclusions from one or just a few cows' MUN values.

There is diurnal (day-to-night) variation in MUN, with p.m. tests often averaging 1 to 2 mg/100 ml higher than a.m. tests. This factor may create considerable test-to-test variation, making it difficult to know when important changes in feeding management have occurred. Test routinely to establish a baseline so you know what is normal variation for the herd.

Herd or group average MUN levels for Holstein, Ayrshire, and Guernsey herds are commonly in the range of 10 to 18 mg/100 ml. Jersey and Brown Swiss breeds tend to run about 2 mg/100 ml higher. New York and Pennsylvania data suggest a herd average target range of 10 to 16 mg/100 ml. While these averages may be used as a reference for interpreting MUN values, it should be understood that the MUN value for optimum milk production and health of an animal has not been defined. Dairy producers and their nutrition advisors should establish a baseline for their herd and monitor changes in MUN to determine if feeding changes have occurred or problems exist.

WAYS TO USE MUN
Use MUN to assess the amount of protein in the diet. A high MUN value may mean you're feeding more protein than the cows require for their production level.

If the amount of protein fed is correct, a high MUN value could mean you're feeding excess rumen degradable protein--urea, soybean meal, alfalfa haylage, or other readily degradable sources of protein. Replace some of the highly degradable rumen protein feeds with a slower or less degradable protein source.

A third option is to evaluate the amount of rumen degradable carbohydrate sources in relation to degradable protein sources. If the rumen bacteria do not have a readily available source of carbohydrate when ammonia is being produced from the breakdown of feed proteins, the bacteria will not be efficient at capturing ammonia and converting it into bacterial protein.

SUMMARY
Single MUN tests are relatively useless in solving feeding problems. Establish a MUN baseline over four to six months and evaluate changes in relation to the baseline values. If conducted routinely, and if a good baseline level for MUN has been established in the herd, MUN tests may be a management tool to improve protein utilization efficiency in dairy cows, decreasing feed costs and nitrogen excretion.

Testing Year Will End 12/31/01

Year End for the 2001 testing recognition and awards will remain the traditional December 31st. Herds will need to be processed by midnight on the 31st in order for that test to be included in the Annual Summary. Herds must also have a test after September 30 to be included.

Cows for Sale

FOR SALE: D+T Farms - Ogilvie, MN is selling the entire herd. A 70-cow Holstein herd.
If interested please call David or Tim @ 320.272.4731.

Holstein Springing Heifers FOR SALE: Having sold a 100-cow herd they are selling heifers as springers.
Call Roger & Teri Hommerding @ 320.764.7726.

Cows For Sale is a service of Minnesota DHIA. Members can advertise for just $2.50 per animal with a maximum of $50 per herd (good for 60 days). For more information, talk to your Field Rep on sample day or call us at 1.800.827.3442.

Web Site of the Month

Our featured web site this month is www.almanac.com

SINCE 1792, The Old Farmer's Almanac has published useful information for people in all walks of life: tide tables for those who live near the ocean; sunrise tables and planting charts for those who live on the farm; recipes for those who live in the kitchen; and forecasts for those who don't like the question of weather left up in the air. The Almanac, North America's oldest continuously published periodical, comes out every year in September. The operation is based in Dublin, New Hampshire.

Happy Holidays!

Best Wishes for a joyous and safe holiday season and successful 2002 from all of us at Minnesota DHIA. We appreciate your continuing patronage.

Thank You.