North Dakota State University
NDSU Extension Service
Vol. 8, No. 3, July 1998
Editorial
Dairy Diagnostic Update
Forage – Does processing corn silage pay?
Housing
Reproduction – Why a heat is not observed after a prostaglandin injection
Herd Health – Mastitis outbreak: what to do before the vet comes
Nutrition
Two issues need to be brought to your attention. First, mark your calendars now for the 1998 State Dairy Convention, to be held October 8 and 9 at the Hospitality Inn in Dickinson. The western region has offered to host a memorable event and invites everyone to attend. This year's theme is "Defining Quality" and will address dairy profitability and lifestyle issues affecting the dairy farm family. The event will also include an update from the North Dakota Dairy Strategic Planning Task Force and a tour of Dakota Dairy Specialties. The agenda is still being finalized and more information will be forthcoming.
Second, the North Dakota Dairy Diagnostic Advisory Team Project is under way. Yes, this first year has limited enrollment due to funding, but we encourage anyone interested in having a future in dairy to apply. A strong application base will help us attain more funding for next year. Be reminded, this is NOT a program of last resort, but rather it's designed to assist dairy farms of any size to get better and if desired, bigger. It's focus is not on problems, but rather on a future for you and your family in the dairy business. Our concept is to build a voluntary team of advisors for each farm. Read more about it from the statewide coordinator, John Johnson (who follows).
J.W. Schroeder
Livestock Specialist-Dairy
I would like to take this opportunity to introduce myself. I am John Johnson, your North Dakota Dairy Diagnostics Advisory Team coordinator, and I'll be looking forward to meeting with many of you in the near future. I grew up on and operated my own dairy farm, my education is in agricultural economics and Ag systems management, and I have an irresistible compassion and respect for the dairy industry. Here is an update on this great opportunity to improve your farm and the industry.
The North Dakota Dairy Strategic Planning Task Force, a group of dairy farmers, processors, and other farm supporters carefully evaluated the situation of the dairy industry in our state. As a result of their meetings the North Dakota Dairy Diagnostics Advisory Team program was developed and is now being implemented with a call for applications. This is a program for all dairy farmers regardless of size or situation. The consensus is, every one of you are important to the success and growth of the dairy industry. The concept is, you decide what areas of your operation you would like to focus on and build your own team to provide the resources needed to reach your goals. My job is to provide a format to be followed and find other unavailable resources. We will continue to accept applications as we see this as a growing program and will continue to seek funding for support, but why wait, start building a team focused on your successful future now. Materials are now being set up for the program and I plan on doing initial farm visits in August. I would welcome your requests for information as I can be reached at my office at NDSU 231- 7993 or my cell at 361-2987.
There is currently much interest in processing (rolling) corn silage to increase kernel digestibility. Researchers at Washington State University with physiologically mature corn plant that had hard kernels have demonstrated increased digestibility and improved milk yields. Does it work with typical corn plant harvested at earlier stages?
Joe Harrison and Lynn Johnson reported in Dairy News, a Washington State University publication, that cows receiving hard dough (before denting) corn silage produced 1.3 lbs. more milk when silage was processed. Milk from cows fed corn silage harvested at milk line was 2.6 lbs. greater. Assuming milk at $.13/lb., this results in $6,169 more income per 100 cows per year with hard dough and $12,337 with milk line corn. This also assumes that cows will continue to milk throughout lactation at this difference. This may not be true, but extra energy would be available for body condition replenishment and would not be wasted unless cows were over conditioned.
New equipment to process whole corn plant can be expensive, but when ungrading it is worth considering. It appears the payback can be relatively fast. Certainly if payback can be achieved in one to three years it is worth considering.
Whether expanding or retrofitting, producers want to employ the best technology to offset construction costs. One such technology is photoperiod or supplemental lighting. As far back as fifteen years ago, there was interest in supplementation of light to dairy cattle during the winter months. A series of experiments at Michigan State University compared the milk production response of cows exposed to 16 hours of light during October to March. In the first study, cows were housed in an unheated free stall and supplemental lighting was provided by fluorescent lights with an intensity of between 11 and 19 foot candles. The supplemental group produced 10% more milk during the first 100 days of the experiment. Percentage of milk fat was unaffected by the length of photoperiod. In a second trial cows were housed in stanchions and provided with 16 hours of light or natural light of between nine and 12 hours duration. Cows in early and late lactation were included in both groups. Cows receiving supplemental light produced 6.7% more 4% fat corrected milk during the winter months when exposed to 18 hours of light per day. However, there was no response in milk yield or composition for first-calf heifers. Supplemental light was provided by high pressure sodium vapor lamps and the average light intensity was 24 and 12 foot candles during the day and night, respectively.
More recently researchers at the University of Maryland investigated the possible hormonal responses to supplemental lighting. One group of 20 cows was exposed to 18 hours of light and six hours of darkness for 84 days. The control group was exposed to natural winter photo-period of less than 13 hours. Supplemental light intensity was 35 foot candles. Cows exposed to supplemental lighting produced 79.4 lbs. compared to 74.6 lbs. for the controls. This response became significant after 28 days of treatment. Unlike previous research there was a numerical but not a significant increase in dry matter intake. The hormone insulin-like growth factor-1 (IGF-1) was increased in the light supplemental cows. This increase in IGF-1 may reveal one possible physiological mechanism for the increased milk yield response.
Michigan State researchers noted one side effect of exposing cattle to long days in the autumn/winter season is that they lose their long winter hair coats early and grow a summer length hair coat over a two to three-month period. In their experiments, in which cattle were housed in unheated barns, no health problems were observed in photoperiod-induced, short-haired cattle during winter. However, what effects short hair may have on energy expenditures to maintain normal body temperature and health of cattle directly exposed to outside winter climates have not been reported. In the trials summarized above, there were no reports of any adverse effects on reproduction. However, further research is needed to determine the optimal light intensity and the long range effects of supplemental lighting on production and reproduction.
In summary there is a positive production response when supplemental lighting is provided during the winter months. It appears that 16 to 18 hours of light with an intensity of between 15 and 25 foot candles is necessary. Cost analysis which considers the extra electrical expenses and fee costs indicate that the additional gain in milk yield makes this a profitable management tool. The extra production associated with a longer photoperiod will probably be seen in those herds where nutrition and milking management are close to optimum. There are some other benefits which may result from the additional lighting. More secondary signs of heat (mucus discharge, swollen and a reddened vulva, etc.), standing and mounting behavior, abnormal discharges and feeding behavior will be noticed during the extra hours of light. How many signs of health and reproductive problems go unnoticed in poorly lighted barns?
The NDSU Dairy Research Center recently installed metal hallide lights to an intensity of approximately 30 foot candles. We also added an automated timer for 18 and six hours of light and darkness, respectively. We're in the process of collecting milk yield and intake data to document the impact of this investment. To date, I can say that metal hallide's white color is more conducive to recognizing estrous signs (sodium vapors look red) and reproductive performance is on an upswing. It's certainly a nicer place to work with all that light!
Sometimes a cow goes undetected in heat after she has been injected with prostaglandin to induce heat. Why? Dr. Steve Milliken, a Lancaster County veterinarian, recently offered 10 possible reasons as posted on the Dairy-L list service.
10. Shot is given at the wrong stage of the cycle. The corpus luteum is responsive to prostaglandin from about day seven to 17 after the previous heat.
9. Cows with cystic ovaries (follicular cysts) do not respond to prostaglandin.
8. Cows not cycling (functionally an anestrus), usually due to a nutritional deficiency, do not respond to prostaglandin.
7. Cows not let out of the stalls in stanchion/tie stall barns will show poor heat activity.
6. Poor footing in exercise area. Cows on smooth concrete surfaces show poor heats. Grooved concrete will improve heat activity; ground or pasture will make it even better.
5. Lame cows. Poor cow comfort, foot rot, hairy heal warts, laminitis or hooves in need of trimming all can keep a cow from displaying heat.
4. Sex and the single cow. One cow in heat may not attract any mounting behavior. Several cows in heat will result in more interaction.
3. She just does not want to. Some cows simply don't show good heats, even if they go through an estrous period.
2. Inadequate heat observation. Once-a-day observation will result in about 50 percent of heats detected; twice a day: 75 percent; three or more times a day: 95 percent. Observation should be continuous for 15 to 30 minutes.
1. Nothing works 100 percent of the time. Five to 10 percent of the time, luteal regression may not occur even when a prostaglandin shot is given at the right stage of the cycle.
When you think you have a mastitis outbreak, there are some steps you should take in order to be ready when you ask your veterinarian for help. Taking these steps will speed up the process and ensure a successful result. If this information is unknown when the veterinarian arrives, additional time will be spent collecting the needed data. The following is an outline of information that should be known before a mastitis problem can be solved.
Determine the character and magnitude of the problem. Find out what type of problem exists. The action level for clinical cases is above 1-2% new cases per month while the level for subclinical cases is somewhere between 200,000 and 300,000 cells/ml in bulk tank milk.
Determine the organism(s) causing the problem. Find out what bacteria, mycoplasma, yeast, fungi or algae are responsible for the mastitis. Repeated cultures give the most reliable results. Obtain culture results from:
Determine which cows are involved. Find out what the pattern of mastitis is within the herd so that the area for corrective action can be noted.
Determine the stage of lactation for the problem. Pinpoint the problem area to a location on the dairy where the problem is starting. This may overlap with the lactation or string groupings.
Look over your DHIA or other records with somatic cell counts for individual cows. Look for patterns with lactation, strings, or days in milk. Have copies available for review.
Determine that the milk system is functioning properly. Rule out any contribution of the milking equipment to the problem. Check teat ends and teat condition for abnormal lesions. Have the machine dealer or other knowledgeable person check over the equipment. Get a written report.
Determine that milking technique is satisfactory. The milking technique should not be allowing mastitis pathogens to transfer from one cow to another during milking. Review detection of new cases by milkers, monitor teat dipping (pre and post) coverage, check out the night crew.
Determine that udders and teat are clean and dry when the cows enter the parlor. Milking dirty, wet cows can lead to environmentally related mastitis problems. Look for yourself on an unannounced visit so that you can be sure of the situation.
Determine that the cow housing is provided a clean, comfortable place for the cows to lie down in between milkings. Housing areas should not contribute to the unsanitary condition of the udder and teats.
Once all this information has been gathered, you are ready to begin solving the problem. In fact, you have probably already made a very good start and have some ideas about where to begin. Now get your veterinarian involved in developing a near term and long range solution to your problem.
Source: The Western Dairyman
Are you ready for MUN? MUNs, BUNs, it all boils down to nitrogen and nitrogen is from dietary protein. What it is not, is an exact science. Consequently, it's either praised or chastised by nutritionists, veterinarians and dairy producers. The purpose of a MUN test is to look into the lactating cow's system to see if she is getting effective use of dietary protein.
Here are some pros and cons of MUN for consideration:
Pros
Cons
Much research and several field trials have armed us with data to apply this technology. However, as stated, scientists are still fine-tuning the process. When do you decide if and when to use MUN on your farm?
The bottom line is either you wait two or three years until researchers have all the answers or you begin using MUN now as a diagnostic tool, realizing that results may be challenging to interpret. As recently stated by Dr. Mike Hutjens, Extension Dairy Specialist of the University of Illinois, "MUN testing should be viewed as a glass half full, not half empty."
Vol. 8, No. 3, July 1998
NDSU Extension Service, North Dakota State University of
Agriculture and Applied Science, and U.S. Department of
Agriculture cooperating. Sharon D. Anderson, Director, Fargo,
North Dakota. Distributed in furtherance of the Acts of Congress
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North Dakota State University
NDSU Extension Service