North Dakota State University
NDSU Extension Service
Vol. 9, No. 1, January 1999
Editorial
Dairy Cow College – 1998
Herd Health
Milk Quality
Nutrition
Selection
Seasons greetings to all. Another year of challenges has gone before us as our industry changes with the times. Unfortunately the signs of a sagging Ag economy means we have fewer farmer neighbors. However, with the challenge has come some innovative and success stories. One highlight has been the implementation of the North Dakota Dairy Diagnostic Advisory Team Program. Jointly funded through a partnership of dairy industry leaders, the North Dakota Ag Products Utilization Committee and the NDSU Extension Service, this `pilot' program is just getting underway. Thanks to the North Dakota Dairy Strategic Planning Task Force, an even larger effort is afoot before the 1999 legislature. As you learn more about this effort, please take an active role in promoting it to your legislators. When it's decision time, your voice really is heard.
Enjoy this holiday season with friends and family. Read on for information pertinent to the state dairy industry.
J.W. Schroeder
Livestock Specialist-Dairy
Cow College is again coming your way, a joint educational partnership between your ADA/DC and the NDSU Extension Service. Gary Hoffman and I are working together on our `traditional' first week in February. This year I will be joined by George Marx from the University of Minnesota-Crookston and Scott Birchall, the NDSU Extension Service Waste Management Specialist. The following is our schedule and a brief agenda. Watch for your statement stuffer coming with your milk check soon.
Schedule
Monday, Feb. 1 Linton Emmons County Courthouse Auditorium,
10:30 a.m., CST
Tuesday, Feb. 2 Dickinson Knights of Columbus, 1531 West Villard,
10:30 a.m, MST
Wednesday, Feb. 3 New Salem New Fair Building, Fairgrounds,
10:00 a.m., MST
Thursday, Feb. 4 Velva Oak Valley Lutheran Church,
10:30 a.m., CST
Friday, Feb. 5 Jamestown Eagles Club, 217 2nd Ave SW,
10:30 a.m., CST
Agenda
10:00 a.m. ADA District Meeting with Registration
11:40 a.m. Lunch (Host: ADA/DC)
12:30 p.m. Forage Reconstitution and Alternatives
Dr. George Marx
1:15 p.m. Facility Enhancements for More Milk
J.W. Schroeder
2:00 p.m. Dairy Waste Management — Your Future Depends On It
Scott Birchall
2:45 p.m. Big Cow, Little Cow — 32 Years of Records
Dr. George Marx
3:15 p.m. N.D. Dairy Diagnostic Program Update
J.W. Schroeder
3:30 p.m. Adjourn
Small grain haylage use for dairy
Consideration for emergency forage needs
Comparing bedding materials for freestalls
Managing dairy manure
Dairy cow waste strategies for Australia
Holstein cow frame size and lifetime milk yield
Using personal advisory teams to enhance your bottom line
Is cold weather linked to new mastitis infections? Should you stop teat dipping during cold weather? Teat skin chapping can become a problem with the onset of cold windy weather. Chapping makes the teat more susceptible to Staphylococcus aureus infections. Research conducted by Dr. Larry Fox and colleagues at Washington State University indicated that teat dipping should be continued during cold windy days but they also suggested that certain practices can reduce the amount of chapping.
Pre- and postmilking teat dips need to include skin conditioner (e.g., glycerin, lanolin), but no more than 10 to 14% because higher concentrations reduce bacterial killing activity. The same germicide probably should be used in both pre-dip and post-dip (e.g., iodine, chlorhexidine, etc.). Teats and udder salves and creams offer no advantage because they are more likely to support S. aureus colonization on teat skin than found with teat dips. Ointments did not improve teat skin condition to offset increased S. aureus colonization on teat skin and teat ends. In some cases, an iodophor teat dip caused more teat chapping and slower healing but S. aureus colonization was less.
They suggest that no teat treatment was possibly a better milking strategy than application of the ointments that they tested. But that's not the best strategy. Instead, they recommend that postmilking test dip should be used but that cows should not be turned outside until teat dip has dried for one minute and teats are blotted dry with a towel before exposure to cold windy conditions.
If a heifer has been in labor for 1.5 to 2 hours or a cow has been trying for 1 hour, without any signs of progress, an examination should be done to determine why progress is not being made. It is better to intervene earlier if you think it is necessary to ensure a live calf. Be sure to watch close-up cows for other signs of calving as well. A cow that frequently assumes a urinating posture or walks with her tail extended for more than 3 to 4 hours may be attempting to calve or could have a twisted uterus, an abnormally positioned calf, or some other problem with delivery.
Sanitation is very important when an examination is done. Infections can be introduced to the uterus which cause infertility and breeding problems. The vulva area should be cleaned with a milk soap (Ivory or iodine soap), the hands and arms of the person doing the exam should be thoroughly cleaned, and plastic OB sleeves worn to prevent contamination of the birth canal and uterus. There is also the possibility of infectious agents in the birth canal that can affect people, so wear sleeves. Check the vulva to see if it is relaxed and large enough for delivery. The vagina should be examined for obstructions like fat, a pelvic fracture, abrasions, or bleeding. The cervix should be examined to assess the degree of relaxation and dilation.
The next step is to determine the position of the calf. Presentation is important for a successful delivery. You should examine all the way up to the elbow or hock. Remember there is a joint (front knee or carpus) between the fetlock and the elbow of the front leg, but not between the fetlock and the hock of the rear leg. If two feet are presented, it is important to determine if they are both front or rear feet, or a combination of each. If the feet are presented upside down (see the bottom of the feet), think about a breech or a twisted uterus.
Always cover the foot (toes) with your hand to protect the uterine wall and vaginal area from a possible tear or puncture. Forced extraction or delivery by mechanical means is very critical. Calf chains are preferred over ropes. The chains should be positioned in two areas, a loop above the fetlock and a half-hitch below the fetlock. This gives a more even distribution of force during pulling to prevent fractures of the leg. It also keeps the foot from folding under and damaging the vaginal canal during delivery.
How much force to exert is the next question. Professionals agree; NO MORE THAN THE EQUIVALENT OF TWO PEOPLE. Pull with the timing of the abdominal press of the cow to help with delivery. After delivery, clean the area again and examine the cow's vaginal canal and uterus for abrasions, lacerations, or bleeding. These may require professional help for suturing or medication. Always check for the presence of a second calf. This will require your arm to be at shoulder depth for a good examination of the uterus.
Cows should be made to stand after delivery and moved around for increased circulation to the muscle area of the rear limbs. Watch for signs of being wobbly or not using a rear leg. These animals may need to be confined in a small lot and kept off of concrete.
When mastitis levels increase, culture bulk tank milk and milk from individual cows to determine the type of mastitis infection in the herd. Bulk tank milk should be tested in herds where DHI somatic cell count (SCC) score is 3.3 or above, or the average actual SCC is above 250,000, or more than 0.5 percent of the cows are withheld from the bulk tank on any day because of clinical mastitis.
Bulk tank culturing is easy, economical, and an important aid in determining the microbiological cause of mastitis in the herd. Sampling only one bulk tank load is not a complete guarantee that contagious mastitis will be detected because Staphylococcus aureus infected cows may shed the organism intermittently. Sample three consecutive bulk tanks. Freeze the first two samples. Commingle these two with the third for culturing. The North Dakota State University Diagnostic Lab will conduct cultures and test for bacteria count, lab pasteurized count, preliminary incubation count, and somatic cell count. The charge for bulk tank screen is $20. Individual cow samples are: $15 for the first sample and $4 for each additional sample submitted at that time. This includes two organisms. Additional organism screen is $3.
In herds with clinical mastitis problems or high SCC, milk samples from clinical mastitis quarters or cows with high SCC should be collected aseptically and cultured to decide which cows should be: 1) held out of the bulk tank, 2) considered for culling, 3) dried off early, or 4) segregated from low SCC, especially at milking. When collecting samples for culturing, be sure to sample cows from different lactations, including those in first lactation that have had elevated SCC, as well as cows in other stages. Include cows that have had clinical mastitis but samples should be collected before any treatment and frozen for later testing. The SCC profile/report can be used to identify cows with highest SCC and the California Mastitis Test (CMT) used to identify which quarters have high SCC.
The Food and Drug Administration (FDA) has amended the animal drug regulations to reflect approval of a new supplemental animal drug application (NADA) which provides for use of Liquamycin LA-200 (oxytetracycline) injection in lactating dairy cattle. Previously, Liquamycin LA-200 was approved for treating beef cattle, non-lactating dairy cattle, calves and swine. The supplemental application of use in lactating dairy cattle was approved by FDA on July 21, 1998. Milk taken from animals during treatment with Liquamycin LA-200 and for 96 hours after the last treatment may not be used for food.
The tolerance for tetracyclines including oxytetracycline, chlortetracycline, and tetracycline are amended to provide for an acceptable daily intake (ADI) and for a tolerance for residue in milk. A tolerance of 300 ppb is established for the sum of tetracycline residues in milk including chlortetracycline, oxytetracycline, and tetracycline. A tolerance of 300 ppb for each of the three tetracyclines is also established.
The previously accepted safe levels for oxytetracycline, chlortetracycline, and tetracycline in milk were 30, 30 and 80 ppb respectively for a sum of residues of 140 ppb. The FDA, states, and the dairy industry have regulated milk at these levels since 1991. With the change in tolerance to 300 ppb in milk, there are no longer any FDA accepted rapid screening tests for tetracyclines in raw co-mingled bovine milk. The FDA is currently working with Charm Sciences to modify their Charm II Tetracyclines Drug Test (Competitive) to detect residues at the new tolerance level. FDA encourages other sponsors of tetracyclines kits to submit performance data on the detection of residues of tetracyclines in milk to CVM for evaluation.
Source: Center for Veterinary Medicine Update
www.fda.gov/cvm/fda/infores/updates/tetraup.html
There's a silent thief roaming through dairy herds. Has it found your farm yet? Subacute rumen acidosis (SARA) is a common and financially significant health issue for dairy herds regardless of size or location. "Rumen acidosis" means the rumen's pH has dropped below healthy levels. "Subacute" means the signs of this low rumen pH are commonly missed or ignored.
Cows are at greatest risk of developing SARA one week before and three weeks after freshening. The high risk is because changes in dry matter intake and concentrate feeding at these times are more rapid than the rumen's ability to adapt.
Is SARA robbing your dairy? Take a look at the table below. The signs can be the result of numerous causes, but a high level of several in early lactation suggests that SARA is on the prowl. If three or more clinical signs are in the problem range, use your nutritionist and veterinarian to investigate if SARA is the culprit.
Start by having your veterinarian determine the rumen pH for several cows at different stages of lactation. If an excessive number of samples show low rumen pH (<5.5), start looking at the list at right of common causes of SARA. Necropsing cows that die at or near freshening and focusing on the development of rumen papillae is also helpful.
If it turns out that SARA is your problem, you need to revamp your procedure for transitioning your cows to the lactating ration and correct other problems as indicated by the list of common causes. This may take some time and energy, but you will be rewarded with improved herd health and increased milk production, which translates into less headaches, more free time, lower costs, and increased profit. A dairy manager's dream!
Signs Typical Problem Range
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Clinical Lameness 15% >5%
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Diarrhea occasional throughout mild to severe cases at
herd high levels in fresh cows
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Feed Intake seasonal changes variable or reduced daily
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Abscesses injection site, abnormal sites, liver,
bruises lung, other sites
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Herd Turnover Rate 35-40% >45%
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Dead Cows 2-3% >5%
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Thin Cows 5% with a BCS <2.25 >20% with a BCS <2.25 at
150 days in milk at 150
days in milk
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Metritis 2-7% >10%
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Ketosis 2-5% >7.5%
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DA's 1-5% >7.5%
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Off Feed 1-5% >7.5%
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(Based on research, unpublished data, and/or
author's experience)
Source: Kenn Buelow, Dairy Management Specialist in Minnesota,
Dairy Initiatives Newsletter
Did you use a good service sire the last time you bred a cow or heifer on your farm? It's easy to say "I always use good bulls" but the real test is whether you could have realistically used a better bull than the one you used.
The objective way to make that comparison is to know where service sires rank on the index you use to select service sires.
Use the table of Net Merit values for active AI bulls from the August genetic evaluations for three dairy breeds. Net Merit is a very useful index for commercial producers because of its emphasis on high productivity as well as longevity. If your last service sire was a Holstein bull with a Net Merit rating of over $193, he was in the top 10% of all active AI Holsteins available. It would be hard to make a "better" decision. On the other hand, if his Net Merit rating was $150, then about half the active AI Holsteins on the market would be a "better" choice! Make the best use of each opportunity offered by an AI service by using high ranking bulls as much as you can.
An article in the August 1998 Journal of Dairy Science by Scott Bascom and A.J. Young summarized the reasons why farmers cull dairy cows. The purpose of their study was to determine whether cows are culled for multiple reasons and whether farm characteristics can help to explain why cows are culled.
According to research summarized from Northeast DHIA data by Larry Jones in 1993, culling rates in the Northeast average 34%. Optimum culling rates have been suggested to be between 25 and 30%. the predominant reasons for culling are reproduction (failure to conceive), health, and low production. The DHIA system allows farmers to select only one reason for culling a cow and this may mask management problems. The accuracy of DHIA culling information could be improved by allowing at least two reasons for culling.
The decision to cull is a complex one. When making a culling decision, farmers may consider many cow factors, such as age, stage of lactation, milk production, health status, disposition, and reproductive performance. Other economic factors such as current milk price, cull cow price, and price and availability of replacement heifers may have a role in determining whether or not to cull a cow. Different farmers will rank problems in different orders when culling cows with several problems.
In the Bascom and Young study, farmers identified a secondary reason for culling for 35% of the cows that were culled, and a tertiary reason for culling was identified for 11% of culled cows. The most prevalent reason was reproduction. Farmers may be unaware of the cost associated with reproductive culling. In herds with less than optimal reproductive performance, farmers must find a balance between income loss caused by excessive days open and income loss caused by high culling rates.
The second most prevalent reason for culling was mastitis. High SCC was rarely used as the reason for culling, however, clinical mastitis was the primary reason for 15% of the cows culled in this study. How producers interpret the difference between mastitis and high SCC is unknown, and culling for mastitis may include both categories. Cows may be culled for mastitis because they never recover from the disease or because of reduced milk production.
The highest producing herds in this study had the highest culling score for abortions. Abortions often lead to culling because cows that abort probably are in their later stages of lactation. Unless the milk production of a cow is high relative to her herdmates, it is generally unprofitable to inseminate her in late lactation which will lead to extended days open, lower mean daily milk production per cow and probably an increased dry period. Reproduction was the primary culling reason for 20% of the cows that were culled. An increased culling score for reproduction was also observed as production increased in Holstein herds. The highest-producing Holstein herds also had the lowest culling score for production and for mastitis.
The authors concluded that farmers need to strive to have herds with high reproductive efficiency, especially as production increases, and to reduce culling rates due to reproductive failure. All cows culled for reproduction are not infertile. By reducing culling rates due to reproduction, the opportunity to replace low producing cows with superior heifers will increase along with overall farm profitability.
Dairy Connection, Vol. 9, No. 1, January 1999
NDSU Extension Service, North Dakota State University of
Agriculture and Applied Science, and U.S. Department of
Agriculture cooperating. Sharon D. Anderson, Director, Fargo,
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