North Dakota State University
NDSU Extension Service
Vol. 9, No. 2, April 1999
Editorial
Calf Management
Colostrum From Johne's Positive Cows
Nutrition
Herd Health
At this writing, the fate of funding for our Dairy Diagnostic Program is still unknown. Considerable time has been spent promoting, publicizing and testifying to the benefits we've seen from the pilot project. Some of the highlights include:
Farms range from 19 to 300 cows in herd size
Farm A. Increased cash flow $7,200 in the first month, without any additional expenditures to the operation, by applying new technology while using only existing farm resources.
Farm B. Less than two months after implementing the advisory team's initial recommendations, this farm reported an increase of 6 pounds of milk per cow per day.
Farm C. Poor quality forages limited this farm's income potential, so the team redesigned the farm's cropping system to improve milk production and efficiency of land and labor use.
Farm D. This dairy farmer is in the process of bringing in a new, young partner, enabling him to increase the size of his herd, improve his lifestyle and help a new dairyman get started.
All 20 Farms. When these participants reach their current set of reasonable and attainable goals, the impact will total $2.1 million of additional gross revenue to the local economy. (This estimate is based on a conservative $12 per cwt. of milk. It does NOT include the multiplier).
It's important to point out that despite the lack of money for new projects, this one has received a lot of attention. So much so, that the Senate Appropriations has amended the Extension budget legislation to include approximately $50,000 for this program. So things are positive despite our struggles.
In the meantime, other means are being taken to find external funding. So if you are interested in being involved in the North Dakota Dairy Diagnostic Program, get on the waiting list.
Have a good spring.
J.W. Schroeder
Livestock Specialist-Dairy
Calf feeding on dairy farms has often been the stepchild, delegated to younger employees or children of the family. As a result, the health and growth of calves was not what it should be according to what we know from research about the potential metabolic development of calves. With the advent of calf hutches and computerized nursing and feeding of calves, the situation improved considerably, especially when measured in terms of the greatly decreased mortality of calves.
Still, even under these two new systems, calves are left to their own choices of what to eat and how much. This is because, typically, hay and calf-starter concentrates are offered freely in addition to the feeding of milk in buckets, bottles or from computer-directed nursing machine nipples.
Calves are born monogastrics, just as humans, horses, rabbits and pigs are, meaning that only one stomach is developed. In calves this is called the abomasum. The other three typical ruminant stomachs - rumen, reticulum and omasum — found in growing and adult cattle, goats, sheep, deer and buffaloes — are not yet developed in newborn calves. Actually, during pregnancy some development of the rumen does occur, but it regresses again and becomes rudimentary at the time of birth.
As far as I know, no research has been done to try to understand this process of regression in utero nor how to prevent it, so that a newborn calf would have the immediate ability to digest hay and grain. Wouldn't that be a great start for our dairy calves? The exception, of course, is the veal calf that is fed neither hay nor grain.
The development of the rumen in calves after birth is a fascinating physiological process. It can almost be prevented, or at least greatly delayed, when a calf is fed only milk, even beyond the normal six to eight weeks of nursing when weaning is postponed. Research has shown that the development of the rumen occurs in two phases: (1) increase in volume and (2) increase in weight, because of (a) growth of muscular tissue, (b) growth of rumen mucosa and (c) growth of rumen papillae with supporting tissues.
These developmental phases occur in response to (1) mechanical and (2) chemical stimuli from the dairy feed intake by calves. In other words, the rumen develops only in response to feed, to its physical properties and nutritional constituents. More specifically, rumen development into a functional organ includes eight factors: (1) the beginning of ruminating, (2) the motility of the developing rumen, (3) the flora and fauna are beginning to become established and is digesting feeds, (4) the rumen mucosa and papillae are starting to absorb nutrients, (5) the rumen mucosa is beginning to metabolize nutrients into new components, (6) voluntary feed intake by the calf is stimulated, (7) blood circulation is increased, and (8) enzymes for the digestion of carbohydrates and proteins, non-existent at birth, are activated.
At birth, the rumen and reticulum of a calf, non-functional as they are, together weigh about 38 percent, the non-functional omasum 13 percent and the abomasum, the functional true stomach, analogues to the monogastric stomach, 49 percent of the total 4-stomach organ mass. This situation is about the same in goats, sheep and other ruminants. At four weeks of age, the different organ weights are 52, 12 and 36 percent, indicating normally developing ruminant stomachs; at eight weeks, they are 60, 13 and 27 percent; and at nine months 64, 25 and 11 percent, according to extensive research at Cornell University.
Ruminating begins to develop slowly after birth. During the first two weeks, a calf on milk ruminates only about three times 15 minutes each at most. By four weeks of age the calf eating grain and hay in addition to getting milk is ruminating about nine periods per day of 20 minutes each, and by the time of weaning, it totals five hours per day.
Parallel to this is the development of a functional rumen. In response to mechanical stimuli — hay, even wood shavings, plastic or sponges — the size of the rumen increases. In now classic research at Cornell University, hay-fed calves developed bigger rumens, but grain-fed calves had longer rumen papillae. Further research showed that the chemical stimuli independent of the mechanical stimuli are responsible for the foundational development of the rumen mucosa and papillae, specifically the volatile fatty acids originating from rumen microbial fermentation of hay and grain. Administering isolated volatile fatty acids to the developing rumen showed that butyric acid was more effective than propionic acid, and this was more effective than acetic acid in stimulating the mucosa and papillae to develop and to increase blood flow to the mucosa.
All this research on mechanical stimuli has led advisors and farmers to emphasize feeding hay to calves as a "scratch factor" for rumen development, ignoring the fact that hay fermentation in the rumen produces mainly acetic acid. Providing grain concentrate instead of hay will, however, hasten rumen development, because of the greater production of propionic acid from grain fermentation in the rumen.
While hay feeding is still important for the muscular development of the rumen and the health of the papillae, new recommendations from Ohio State University suggest now that hay should be part of the calf diet only after weaning, specifically after weaning at four to five weeks. If calves are weaned at eight to 10 weeks of age, they should get no more than 1 pound hay/day, beginning from six weeks of age, which would ensure that calves eat a sufficient amount of a coarse grain concentrate.
Generally, calves do not eat much hay to start. They waste a lot. Not only will limiting the hay feeding reduce unnecessary and costly waste, but calves will better fill their high energy requirements, which are not satisfied when they are allowed to eat any amount and they choose hay over grain concentrate. The result is slower growth of the calf, which, of course, is in opposition to the goal of calf raising.
Thus, the new recommendations — to wean earlier while feeding only grain concentrate and no hay, or to delay feeding hay until the calf is six weeks of age or feed hay only after early weaning at four to five weeks - will optimize rumen development and put more money into the dairy farmer's pocket.
Source: George F.W. Haenlein,
Cooperative Extension Dairy Specialist, University of Delaware
Mycobacterium paratuberculosis, the organism responsible for Johne's disease is a difficult organism to eliminate from dairy herds. However, many producers have initiated programs in an attempt to eradicate the organism from their farms. Below are several questions that have been posed regarding feeding colostrum and the importance of feeding colostrum.
Why shouldn't I feed colostrum from Johne's positive cows? One of the methods that M.paratuberculosis is spread throughout the herd is by the consumption of infected colostrum. Johne's organisms may be shed into the colostrum of infected cows. Research has shown that this is one important vector of disease transmission. Therefore, it is important to discard the colostrum (and milk) from Johne's positive cows.
Can I feed colostrum from Johne's positive cows if it has been frozen? It is unlikely that freezing will kill M.paratuberculosis — particularly if the freezing is not at low temperatures or for an extended period. Therefore, it is probably NOT safe to feed colostrum from Johne's positive cows — even if it has been frozen.
Can I feed colostrum from Johne's positive cows if it is pasteurized? Pasteurizing milk or colostrum increases the temperature of the colostrum to very high temperatures (71C) for a short period of time. Research on whether pasteurizing is completely effective in killing all M.paratuberculosis is still unclear, although it appears likely that commercial pasteurization is effective in killing all M.paratuberculosis in milk. Colostrum is another matter, however. There are several reasons that pasteurization is not recommended for colostrum: colostrum is much thicker and denser than milk. This makes it more difficult to raise the temperature sufficiently to ensure that all M.paratuberculosis organisms are killed. There are a large number of leukocytes (white blood cells) in colostrum. These cells carry the organisms, so it is likely that colostrum will effectively concentrate the organism. Again this makes pasteurization less effective. Many on-farm pasteurizes are not as effective as commercial firms, therefore, the risk of leaving viable organisms is significant. It is important to remember that pasteurization is not sterilization — pasteurization reduces microbial load — it does not completely eliminate it. Some on-farm pasteurization methods, especially batch pasteurization (elevated temperatures for 30 min. or more) can destroy the lgG that are so important to providing the calf with passive transfer. For these reasons, it is recommended not to feed pasteurized colostrum from Johne's positive cows.
First, you can use colostrum collected and banked from cows that have been tested and are Johne's free. You may have to collect two or more milkings from these cows to have sufficient colostrum for all your calves. This will necessarily mean that the overall colostrum will not be as high quality (lgG concentration) as if you could feed only first milking colostrum to all calves. Use a colostrum supplement. Supplementing colostrum with commercial supplement products to increase the lgG concen-tration can help you stretch your colostrum supply. Be sure the product you choose contains sufficient lgG, and the absorption kinetics of the product are acceptable. For more information on colostrum supplements see "APC Calf Note #18 - Using Colostral Supplements." Supplements may be used to increase the lgG concentration of second milking colostrum, or may be used to completely replace colostrum if necessary. If you feed no colostrum, be sure to feed a sufficient amount of supplement to provide calves with approximately 100 g of lgG in the first 24 hours of life (preferably, the first 12 hours). Do not pool colostrum. If you have a cow that is shedding the organism but is not showing clinical signs and has not been tested, you may infect many calves if you feed that colostrum.
A comprehensive testing and eradication program for Johne's is important to identify those cows that are contributing to the overall Johne's problem on the farm. As the cost of testing declines and the reliability of testing increases, the problem of M.paratuberculosis should decline on most dairy farms.
Written by Dr. Jim Quigley, American Protein Corporation
Anytime I go into a barn and see an empty or near an empty feed bunk, my first question is when is feeding time? If I happen to arrive ten minutes before feeding, or in the middle of cleaning the bunk and refilling it, we're okay. If not, it's time for a discussion. Under feeding dairy cows is a serious error in dairy management. Any steps that we do to restrict dry matter intake costs milk production. One way to address limit feeding is to adopt a system of scoring your feed bunk. In a free stall operation you need to check all areas where feed is offered. In a tie stall barn all bunk areas in front of cows must also be checked. Dairy feed bunk assessment by the feeder or manager is a good idea to adopt. A good time to check feed bunks is one hour before the next feeding. This holds if the herd is fed once or more often per day. The most typical scoring system used is as follows:
0- no feed
1- scattered feed left (<5% of amount fed)
2- thin layer remaining (5-10% of amount fed)
3- a layer of two to 3 inches (approximately 25% of amount fed)
4- three or more inches remaining (>50% of amount fed)
5- feed untouched
A score of 0 or 1 is indicative of under feeding the herd. This is a problem that must be addressed to achieve maximum feed intake. Cows that are being forced to clean up the feed bunk are being underfed. Anytime the cows are cleaning up the last 5%, there are some, if not all cows that are not eating to their maximum intake. Often there is some forage material that is less palatable, spoiled, or otherwise of poorer quality. Cows usually sort these parts of the forage out, and under ample feed avail-ability, will leave it behind. When forced to consume this feed, we generally sense that the cows are hungry. This feed is usually of lower digestibility and will itself reduce the cow's feed intake. Feeding should be increased by 5% or more until a score 2 is observed. If daily feeding has to be adjusted by more than 5%, forage dry matters and the feeding program should be checked. A score of 2 is ideal as long as the cows are to be fed within half to one hour. A score of 3 indicates overfeeding. Feed bunks should be cleaned out and the feed offered should be reduced by 5%. Again, forage dry matters and feeding programs should be checked to see what is the reason for the excess feed remaining. Stale or moldy feed being offered, or incorrect feed mixes are often the cause. Scores of 4 or 5 represent serious feeding problems. Each of these needs attention. We know that weather conditions and other extremes from day to day normal operations can affect dry matter intakes and lead to day to day fluctuations. Therefore use common sense when checking the feed bunk on a single observation. Other management aspects such as failing to have the feeder note cow movement from group to group can cause abrupt changes in feed bunk scores.
Daily feed bunk scoring can help the feeder or herd manager spot problems in forage dry matter, forage quality, or ration problems. It is a critical step to good feeding management to assess the feed bunk often.
Source: A. Jud Heinrichs, Dairy and Animal Sciences Extension, Penn State Univ.
The European Union (EU) has reduced their accepted level to 400,000. Any milk shipped into these countries must also be less than 400,000. The National Conference on Interstate Milk Shipments will consider this change again in May. The EU computes a geometric mean over three months rather than an arithmetic average. A geometric mean of three samples is determined by multiplying the three numbers together and calculating the cube root. The advantage to the geometric mean is that a single high somatic cell count has less impact. Not everyone agrees to the adoption of 400,000, however many feel that there is need to establish a world standard for SCC. Research results suggest that at 400,000 SCC, 13% of quarters in a herd would be infected while 24% of quarters would be infected in a herd with a bulk tank SCC of 750,000. It is unclear at this time as to how a limit of 400,000 would be regulated if accepted. The National Mastitis council Board of Directors recommends a gradual decrease over several years.
One possible implementation is that a herd would be placed on probation after two consecutive months that the geometric mean exceeds the regulatory limit and would be suspended if the third consecutive 3-month geometric mean is in violation and that tests would be conducted weekly, which is currently done by some. Successful mastitis prevention and control includes: (1) Controlling environment, housing and teat contamination between milkings, (2) Routine monitoring of milking procedures, (3) Milking sanitation and hygiene, (4) Milking system design and maintenance, (5) Dry cow management and therapy, (6) Monitoring SCC and rate and type of infection, (7) Herd segregation or backflushing, and (8) Culling chronically infected cows.
Source: Gerald M. (Jerry) Jones, Extension Dairy Scientist, Virginia Tech
Dairy Connection, Vol. 9, No. 2, April 1999
NDSU Extension Service, North Dakota State University of Agriculture and Applied
Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director,
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North Dakota State University
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