February 2000

• 13th test in Production Averages Section - compare same month this year & last
• Lactation 2 breakout in all Lactation sections
• Management Level Milk calculations are new, based on research using today's lactation curves. New MLM Summary section.
• New SCC summaries
• New Reproductive measurements
• New "Peak and Persistency" section
• Larger print on the front of the Summary
• Summary of cows leaving the herd by lactation and by reason (if reported)
• Number of cows milking projected for next 6 months including heifers (if breeding & pregnancy information is reported)

"Current SCC Evaluation" summarizes SCC by lactation number and by level. Use this box to compare lactation's. Is the percent infected in lactation one lower than lactation two? Are both lower than lactation's 3 or higher, as expected? Looking at the % cows by linear score, are there many cows in the high SCC range (4,5,6 and 7,8,9) or is the SCC for a group being raised by a small number of very high cows?

"Yearly SCC Summary" looks at SCC by days in milk. Data included is all sample days in this lactation for all cows in milk. Use this box to see where SCC is highest; early, middle, or late lactation. Does SCC go up during lactation? Is the trend different for lactation one animals compared to other lactation's?

Changes in SCC Status "Fresh vs. Last Dry Off" compares the last SCC a cow had before drying off in the last lactation to the first SCC test this lactation. Since we are comparing to last lactation, cows in lactation 2 or greater are included.

• "Cures" are cows that finished the last lactation infected with mastitis (SCC over 200,000), and the SCC on her first test this lactation was negative (under 200,000 SCC).
• "New Infections" are if she finished last lactation negative and freshened infected with mastitis.
• "Negatives" are cows who dried off negative for mastitis and were still negative when they freshened.
• "Chronics" were high at the end of the last lactation, and were still infected at freshening.

Is the percent Cures higher than the percent New Infections? If not, you might want to look at the dry off, dry period, or early lactation management practices. Is the percent Chronics under 15%? If not, review mastitis management and culling practices.

Changes in SCC Status "Current vs. Last Test" uses the same definitions as above and can be used in the same way to evaluate progress from the previous (last) test to the current test. Only cows with a SCC on the last test and the current test are included. The New Infection Rate divides the number of New Infections by the number of cows with a SCC on the current and previous test.

Production Averages "Quality" represents a significant addition in SCC data to the Rolling Herd Average section. Data is listed for each sample day so you can chart progress, and spot seasonal trends.

• The "Raw SCC" column is new and is here by popular request.
• The "SCC LS" (Linear Score) is less affected by individual cows with extremely high Somatic Cell Counts and is considered more useful in evaluating SCC trends across the months.
• "Number Infections" refers to the number of cows with the latest sample day SCC over 200,000 and may be a more useful number to look at when comparing one month to another, or looking for season trends.
• "Fresh Infections" refers to the number of cows in the herd who had their first sample day in this lactation on the latest test, and had an SCC over 200,000.
• "% New Infections" is the New Infections divided by the number of cows in the milking herd on this test who did not have a SCC over 200,000 on the last test. This is the percent of cows who could have become new infections that did become new infections. Note that the difference between new infections here and in the "Changes in SCC Status" is the denominator.

• "Pregnancy Rate" - Heat Detection Index divided by services per conception or, Heat Detection Rate times Conception Rate. This number tells you the per- centage of heats that result in a pregnancy. If this number were 100%, it would mean that you would catch all heats after 50 days in milk, breed all cows on the first heat, and each breeding would result in a pregnancy.
• "CI - Standard Deviation (Months)" - The standard deviation of Calving Interval. The standard deviation is a measure of variation around the average. A small number indicates most cows have a similar length Calving Interval.
• "Management Calving Interval" estimates the average calving interval without using breeding information. The variables used are annual average DIM from averaging the test-day DIM in the Production Averages section, and the Average Days Dry from the Dry Period Summary. The calculation is: (2 X DIM + Days Dry) / 30.4 One of the uses for MCI is to remove the affect of quick culling of problem cows from the calving interval calculation. Early culling of problem cows would cause the Calving Interval to appear low or normal, when getting cows bred could actually be a problem.

All DHIA Labs in the US will switch to True protein on May 1, 2000. This coordinated nation-wide change will allow for a uniform transition to minimize the affect on the industry, including data flowing from DHIA to USDA, which is the basis for genetic evaluation (Bull Proofs), and research.

The change in payment pricing from Total protein to True protein content in milk has now come about. This means you will see a small change in the protein test you get back on your milk check. Total protein includes non-protein nitrogen (NPN). True protein is lower than Total or Crude protein because True protein looks only at Protein, not NPN. True protein equates to useable protein for milk processors. Herds running a Total protein test around the state average of 3.2 should expect to see a drop to about 3.0 with NPN eliminated from the protein test.

Researchers indicate that NPN is not genetic, but is related to feeding and management.

The Minnesota DHIA Annual Meeting will be held on March 1, 2000 in St. Cloud at the Radisson Hotel and is scheduled to run from 10:45 to 12:30. The Radisson is located across the street from the Convention Center downtown on the river, just off Highway 23. The Central Minnesota Farm show is being held at the same time at the Convention Center.

Featured speaker is Dr. Steve Eicker, one of the creators of Dairy Comp 305. Following the Annual Meeting and lunch, Eicker will be speaking on developments in the on-farm software from Valley Ag Software. All Minnesota DHIA members using Dairy Comp 305 or considering using it are welcome to attend the afternoon session.

On February 29th, from 11:00 a.m.-3:00 p.m. at the Good Times Restaurant in Caledonia, MN the Houston County Dairy Roundtable is sponsoring a dairy workshop by noted veterinarian and milking equipment specialist Dr. David Reid. Topics will include: milk quality assurance, milking practices and the maintenance and calibration of milking equipment.

You are requested to pre-register for lunch by contacting the Houston County Extension office by February 25th, at 507-724-5807. Lunch will be provided compliments of the Caledonia and Eitzen Vet Clinics. All dairy producers are welcome to attend.

Dairy L is a world wide E-mail "listserve" that allows you to post questions about dairying, and recieve answers by e-mail. The questions range from milk price policy to how to get rid of gophers. There is no cost and Dairy L will enable you to get different solutions to a problem you have. Some replies will come from experts, others from everyday dairy farmers.

The web site for Dairy L is: www.wam.umd.edu/~markv/Dairy-L.html It contains the instructions for signing up and other information on Dairy-L.