May 2001
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NM$ VALUES NEEDED FOR 4-H ANIMALS
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If you have animals in 4-H, please sign up for the Genetic Evaluation reports
so that you can get the Net Merit (NM)$ values on your 4-H animals. The cut-off
for USDA's run was April 10th. By May 10th, the Genetic Evaluation information
will be updated to our Dairy Records Processing Center (DRPC). At that time,
the Heifer Genetic Evaluation report and Genetic Evaluation report for cows will
be ready for print. On your next test you should get the updated reports with
NM$ values included. You will need these for production classes.
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MINNESOTA FEEDLOT RULES FOR MANURE TESTING
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The Minnesota Feedlot Rules state the following: "Manure from all storage areas
holding manure from more than 300 animal units must be tested for nitrogen and
phosphorous at least annually for the first three years and at least once every
four years thereafter." 300 animal units equals approximately 160 dairy cows
plus heifers and calves on a typical dairy.

The rules also state: "Manure from all storage areas holding manure from 100 to
300 animal units must be tested for nitrogen and phosphorous at least once every
four years, or more frequently if management changes could lead to varying
nutrient content. Individual stockpiles and manure packs generated by fewer
than 100 animal units are not required to be tested." 100 animal units equals
approximately 55 dairy cows plus heifers and calves on a typical dairy.

For a postage-paid manure analysis kit, please call the Stearns DHIA Lab at
1-800-369-2697. The charge for N, P and K testing is $20 for either liquid or
solid samples. Guidelines on how to take a sample are included in the kit. The
Stearns DHIA Lab tests manure for 100+ custom manure applicators in the five
state area as well as producers of all types of livestock and poultry.

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ID YOUR COWS FOR LIFE WITH PLASTIC EARTAGS
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In addition to Fearing eartags, Minnesota DHIA now offers the full line of
Z-tags for sale. Studies indicate up to 95% retention rate!

We offer several different styles, including 1-piece numbered or blank, 2-piece
button back numbered or blank, long neck calf tags, feed lot tags, sheep & goat
tags. We also have several printing options available, such as American ID,
farm name, management number, sire & dam name, etc. For more information or
to order, please call Joyce at 800-827-3442.

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DON'T WASTE YOUR PROTEIN
Sandra Godden, College of Veterinary Medicine, University of Minnesota
Jim Linn, Department of Animal Science, University of Minnesota
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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 require-
ments 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 kid-
ney 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 rela-

tively 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 aver-
aging 1 to 2 mg/100 ml higher than a.m. tests. This factor may create consid-
erable 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 base-
line 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 de-
gradable 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 pro-
duced 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.
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CYNDI STIFTER RECOGNIZED AS ROOKIE OF THE YEAR
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Wright County Field Rep, Cyndi Stifter, was recognized as the 2001 Rookie of the
Year at the Wright County Annual Meeting held in Rockford. This distinguished
award goes to a new field representative with less than 2 years of service and
an outstanding record.

Cyndi first started testing for Minnesota DHIA in October 1999. Being a herd-
owner herself, she had a pretty good idea of what was involved long before she
became a field rep. Her unit takes her all over the county and she willingly
puts on many miles to get to them. She's also eagerly helped out with relief
testing in neighboring counties.

Cyndi is currently testing 38 herds, including 4 new herds she recruited last
year. She is testing each herd an average of every 33.4 days and getting the
reports processed in an average of 2.6 days. Her unit is 2883 cows strong.

We at Minnesota DHIA are glad Cyndi joined our team and hope that she stays for
some time to come. Keep up the great job, Cyndi!

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COWS FOR SALE
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For Sale - Holstein dairy herd. 18 stall cows. For more information, please
contact Louis at 218-253-2511 Schafer Farms, Red Lake, MN.

Guernsey National Convention Sale - June 25, 2001 - Jordan, MN - Scott County
Fairgrounds. 50 lots selling. For free catalog or more information call the
American Guernsey Association at 614-864-2409 or visit them on the web at
www.usguernsey.com. Or Call Paul Fritsche of New Ulm, MN at 507-359-7766.

Lynn Peterson of Pope County has 6 holstein heifers for sale. They are due
to calve in May. Call Lynn at 320.965.2378.

For Sale - Complete Holstein Dairy Herd. 95 cows, no BST, young herd, DHIA
records. Please call Roger & Teri Hommerding at 320-764-7726.

David Kanopik of Morrison County is selling 22 Holstein cows, several are
registered. For more information, please call him at 320-547-2476.

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 800-827-3442.