North Dakota State University
NDSU Extension Service
Vol. 7, No. 4 October 1997
Editorial
Clinical Mastitis Can Affect Reproductive Performance
Milking Frequency Observations
Highlights in Dairy Science Research
Electronic Tips for Dairy Producers
"North Dakota dairy producers want action..." was the headline in the Bismarck Tribune following the Dairy Summit meeting held Monday, August 19. Action will be necessary in the very near future if North Dakota is to sustain its dairy industry. The necessary action, however, is the question with no one answer. As a result, a steering committee has been initiated to begin addressing this need. The answers lie within the members of the industry (producers, processors and it's providers).
It's the hope of the group that a process can be unveiled at this year's State Dairy Convention. This would be a great time for you to come together in the spirit of action. Plan now to take in this year's convention and have your thoughts on developing the future of the dairy industry. A copy of the dairy convention schedule follows. Please note that it's only 1½ days — a condensed agenda to accommodate less time away from home.
J.W. Schroeder
Extension Specialist-Dairy
Results from a University of Tennessee study suggest that clinical mastitis during early lactation can have a profound effect on reproductive performance of dairy cows. These results were not restricted to Gram-negative mastitis pathogens as observed in previous studies, since similar responses were seen in cows with clinical mastitis due to Gram-positive and Gram-negative mastitis pathogens.
Days to first service were significantly higher in cows with clinical mastitis before first insemination (93.6 days) than in all other groups of cows (71.0 days). Services per conception were higher in cows with clinical mastitis after their first service (2.9) than in cows with clinical mastitis before first service (1.6) and in cows with no clinical mastitis or cows with clinical mastitis after confirmed pregnancy (1.7). Regardless of clinical mastitis status, cows with > 5 lactations required significantly more services per conception than all other parity groups.
Days to conception in cows with clinical mastitis before first insemination (113.7 days), and in cows with clinical mastitis after first insemination (136.6 days) were higher than in control cows and cows that developed clinical mastitis after confirmed pregnancy (92.1 days). The breeding period for cows with clinical mastitis between first insemination and pregnancy was higher than in all other groups of cows.
Studies examining the mechanisms by which mastitis influences reproductive performance in dairy cattle are currently underway.
Source: NMA 1997 Annual Meeting Proceedings, p. 274.
Many variations in milking frequency and inter-milking intervals have been tried over the past few decades. Usually these have been for social, production management or economic reasons. As milk production per cow and herd averages have increased, the interest in milking frequency has also increased. Summary points from a paper on milking frequency presented at this year's Western Dairy Management Conference follow:
Source: 3rd Western Dairy Management Conference Proceedings (1997), pg. 79
This summer I attended the American Dairy Science Association meetings at Guelph, Ontario which included my poster presentation on some of the corn gluten work here at NDSU. Attending this annual event gave me the opportunity to hear many excellent research reports. Here is a summary of a few reports you may find interesting:
The economic benefits of using a computerized management information system seems to be the rage. DHIA producers in North Dakota have recently switched to PC-DART, one of the premier dairy information systems. A recent study covered this software area.
The authors followed Texas dairy herds over time and compared herds that had used a management information systems (MIS) computer program. A MIS program is a computer software program that uses herd information to aid in management decisions. PC-Dart was the most common MIS used.
Two hundred fifty non MIS herds and 72 MIS herds were evaluated. Most herds were using the PC-Dart software as their MIS. No significant differences between MIS and non-MIS were found in the first evaluated year (1983). By 1996, however, MIS herds had a 2,000 lbs/cow/year advantage. Herds often made a large increase in production during the first year of use, and they maintained that advantage over time. For an average herd using a MIS (467 cows in size), there was an accumulated $29,000 benefit to those herds using a MIS.
For an average herd (n=467 cows) and a $29,000 benefit. Large "jump effect" in first year.
The authors were dairy scientists from Texas A&M Univ. and an Agricultural Economist Wageningen Agricultural Univ. in the Netherlands.
Some DHIA herds are beginning to use MUN (milk urea nitrogen) tests to fine tune dairy diets. If you're one of those new users of MUN, the next two reports will be of value.
The presenter described the metabolic pathways for urea, ammonia, protein and nitrogen in cattle. After the review, some of the key points were:
Producers and consulting professionals should not measure MUN levels for several days after ration changes, due to the time required for MUN levels to change and accurately reflect nitrogen balance.
Significant AM vs PM differences can occur. When sampling milk for MUN, a daily composite sample is better than just AM or PM. Alternating between AM and PM sampling, which can be common in some DHI systems for measuring MUN, should be avoided.
Azotest "dipstick" test for MUN is accurate within 5 mg/dl, but subject to operator interpretation and variation in operator technique.
The energetic "cost" of detoxifying excess ammonia when comparing a 17% crude protein vs a 19% diet, is equivalent to .4 kg (1 lb) milk per cow per day.
If you increase the rumen undegradable protein, while reducing the degradable protein and keeping the crude protein levels the same, the milk urea nitrogen (MUN) levels are lower.
Values for RDP and RUP are difficult to obtain on many feedstuffs and rations, limiting their practical use.
MUN levels were a better predictor of ratio between ration protein and fermentable energy than was protein. Without the extra fermentable carbohydrates for use by the rumen microbes, high levels of dietary protein result in high MUN levels.
Jerseys had higher MUN levels than Holsteins when fed a 20% crude protein diet.
Average MUN levels were 14 mg/dl for over 300,000 samples in 1731 herds in PA fed according to typical feeding patterns in that part of the United States.
Milk urea nitrogen (MUN) levels are being used to evaluate dairy cattle rations. It is not yet clear how quickly after a ration change will MUN levels reflect the dietary change. The authors designed a study to determine how fast the changes might occur.
They gave cows a water drench into the rumen with a stomach tube. The water contained 680 grams of starch, 75 grams of urea, both or none in a well designed scientific experiment. The urea and starch were chosen as they would likely yield results that would reflect the fastest the MUN changes might occur.
Cows were milked 3x daily, and there was significant differences in MUN levels between the three milkings. The dietary drench of starch or urea caused changes in MUN levels in the first milking after treatment, suggesting that MUN levels can be measured quicker after a ration change, than the several day wait often prescribed.
Cow health is paramount to economic production. Our challenge for high production herds is the incidence of DA's (displaced abomasum or "twisted stomach"). These Ontario researchers tested the commercial kits.
Two related papers were presented that concerned the relationship between incidence of subclinical ketosis and left displaced abomasum (DA). The authors found that cows with subclinical ketosis during the first two weeks postpartum were at significantly greater risk for DA. It is not known whether the ketosis causes the DA or ketosis is the result of some rumen malfunction that subsequently becomes a DA. Metabolic profiles were not different prepartum, even though there were significant differences postpartum.
Two commercial milk ketone tests, Ketocheck and Ketolac, were evaluated for use in prediction of the cows at risk of DA. Ketolac was found to be a better predictor of risk for DA. Almost 50% of cows that had a level greater than 100 mmol BHBA/l milk using the Ketolac test ended up with a DA. Over 95% of DA cows had a 100+ mmol BHBA/1 level with the Ketolac test.
Further research is required concerning what treatments might be effective in preventing cows at risk from getting a DA.
Many of you are asking about the effectiveness of cloth towels and appropriate cleaning. Using the proper laundering technique can be beneficial.
Cloth towels were laundered in a number of different ways to determine which method killed mastitis-causing organisms. The researcher washed towels in hot or cold water, used or didn't use bleach and dried some towels with forced hot air. Standard temperatures, bleach concentrations and washing machines/driers were used in a carefully designed study to look for direct effects and interactions.
The scientist found that a laundry procedure that included JUST ONE of the following was effective in getting rid of contagious mastitis causing organisms: hot water wash, use of bleach during washing or forced hot air drying. Significant numbers of mastitis-causing organisms were found when towels were washed without hot water or bleach or were not dried in a drier.
The author is a mastitis expert at Washington State University Veterinary School.
If you have a computer and a modem you are ready to tap some really interesting sources of dairy information. Once you have access to the Internet through a local Internet service provider and paid your provider, all the services below are free.
Most well known is the forum called DAIRY-L. It is co-moderated by extension dairy specialists Mark Varner (University of Maryland) and Roger Cady (Washington State University). The subscribers include producer-farmers, suppliers of agricultural goods and services, veterinarians, educators and others. Each subscriber receives daily a number of e-mail messages submitted by other subscribers. For example, recently there was an exchange about feeding waste milk to calves asking if there are risks involved. An earlier exchange dealt with bloating in 5 to 15 day old calves. In each case a variety of ideas are submitted for the subscriber to read and consider.
One of the nice features of Dairy-L is that all the messages are saved (in what the moderators call the "archives"). Then if you want to know what has been submitted on a subject you just ask their computer to search the archives for all the messages related to that subject. For example, when we had a problem with salmonella we searched for "salmonella." Among the thirty-plus messages were two that applied directly to our situation and a third gave us the name and telephone number of a person to contact who was a specialist in salmonella in dairy situations. Similar searches are possible in areas of housing, health, nutrition -- you name it.
To subscribe to DAIRY-L, send an e-mail message to: listserv@umdd.umd.edu
Modify the following line and put it in the body of the message and NOT the subject:
SUB Dairy-L Firstname Lastname
For example, if your name is Jane Doe, then you would send a message that had the following line in the body of the message:
SUB Dairy-L Jane Doe
Another helpful source of longer messages such as newsletters and abstracts is called DairyNew. It is brought to us by Mark Varner, Stan Fultz and Ken Olson. A number of universities have regular dairy newsletters that deal with virtually every dairy-related topic. These letters are usually about two pages long and deal with a timely topic. Most e-mail software permits you to save these on your hard disc for future reference.
To subscribe to DairyNew, send an e-mail message to: listserve@umdd.umd.edu
Modify the following line and put it in the body of the message and NOT the subject:
SUB DairyNew Firstname Lastname
For example, if your name is Jane Smith, then you would send a message that had the following line in the body of the message:
SUB DairyNew Jane Smith
If you have software for accessing the web you might want to visit Jim Quigley's Calf Notes web site by pointing your browser at: http:/funnelweb/utcc/utk/edu/~jquigley/calfnotes.htm
A few of the currently available CALF NOTES are entitled:
- Colostrum Feeding: To Nurse or Not to Nurse
- Colostrum Feeding: How Much Colostrum is Enough?
- A Primer on Colostral Immuniglobulins
- Timing of Colostrum Feeding
In this Calf Note, Jim explains why early feeding of colostrum is important for calf survival. You will be interested to read about how the number of absorptive site sin the intestine start going down as soon as 30 to 60 minutes after birth. He talks about winning the race between bacteria and antibodies. Convincing ideas.
- Respiratory Acidosis and IgG Absorption
- Freezing and Thawing Colostrum
- Water, Water, Everywhere...
- Rumen Bacteria for Calves (Or, What Culture?)
- Methods of Feeding Liquid to Calves
There are more — visit this exciting web site and see for yourself.
Dairy Connection, Vol. 7, No. 4, October 1997.
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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North Dakota State University
NDSU Extension Service