Dr. Bill Croushore, July 2012
Biosecurity is a word that many people, even farmers, are unfamiliar with but it is critical to the health of a herd of livestock. The definition is, simply put, the practice of preventing the introduction of an infectious diseases into a population of livestock.
I see a lot of barns with a big red sign on the door to the milk house that reads, “STOP- this is a biosecure area. No admittance without prior permission!” The sign is implying that there is a high degree of biosecurity, but the actual practice of preventing the introduction of disease may be nonexistent. True biosecurity is more than hanging a sign on a door with the hope that it will keep the bogeyman out.
The traditional “closed herd” is a good example of the practice of biosecurity. Unfortunately, the truly closed herd is practically nonexistent today. Admittedly, many herd owners can’t recall buying animals in many years but that doesn’t necessarily qualify their herd as closed. I can remember having conversations with more than one farmer during a Johnes disease risk assessment who claimed that his herd was closed. When I asked about their use of a bull, they realized that they had purchased new bulls regularly and their herd was, in reality, far from truly closed. Even herds that never bring in new animals have visitors from other farms like the route truck driver, hoof trimmer, breeder, nutritionist and, yes, even the veterinarian who may have been on another farm earlier in the day.
Fortunately, there are sound practices that can prevent the proverbial train wreck of infectious disease even if a herd isn’t truly closed. Here are some tips, although the list is not exhaustive. If you are in the market to buy replacement animals, buy them only from a trusted source. If necessary, testing can be done on the animals for Bovine Viral Diarrhea virus (BVD), Johnes disease, and contagious mastitis among others. While not all testing is perfect, it can help screen out some carrier animals.
Make sure your herd is on a sound vaccination program for contagious diseases like respiratory disease developed by your veterinarian. If purchasing animals, it would be wise to see that the purchased animals are also vaccinated prior to shipment. Not only will it prevent introduction of infection to your animals, but also hopefully prevent illness in the purchased animals.
If your farm has a lot of visitors, or may be hosting a community event, a footbath station with disinfectant may be useful to prevent the introduction of a contagious disease. Summer show season is upon us and with it brings new infectious disease challenges. There is probably no better way to cause a respiratory infection in an animal than to truck it to a show barn and comingle it with a bunch of other stressed critters. Here are several things to consider. First, make sure respiratory vaccinations are current. Intranasal vaccination just prior to the show is cheap insurance, even though it isn’t required at most shows. Unfortunately, approved respiratory vaccinations don’t exist for sheep and goats. Second, when the animals return to the farm, make sure the ventilation is excellent where they are housed. A good rule of thumb is that if you can smell ammonia in the barn, the animals are at increased risk of respiratory disease. Ammonia inhibits the tiny, hair like cilia on the cells of the respiratory tract that help remove infectious particles from the lungs. Third, consider a quarantine period upon returning if you have the space. Most people recommend 30 day quarantine, however, 2 weeks is probably plenty. Quarantine prevents any infection that may be present in the animals that were at the show from spreading to animals that were left at the farm.
Finally, make sure there is always clean water available and keep the animals well fed. The immune system requires a lot of energy to function properly and the extra calories can make a difference.
Biosecurity may be a twenty dollar word, but being familiar with its principles can potentially be priceless. Ask your veterinarian about other steps that can be taken to prevent an infectious disease outbreak.
Dr. Croushore is a veterinarian with White Oak Veterinary Clinic in Berlin, and services farms in Somerset, Bedford, Westmoreland and Fayette counties. If you have a question for the veterinarian, send it to email@example.com
Most people would agree that farming is hard work. Even today, with all of our technological advancements, farmers still earn a living by the sweat of their brow.
I remember as a youngster the job I dreaded the most. It was picking rocks from a field. Rocks can damage equipment and reduce yield, so farmers like to have them removed from the crop fields.
Unfortunately, there is no easy way to accomplish this task. Usually, a person or people will walk around the tilled field, pick up the rocks and chuck them into a wagon. My uncle used to pay me to do this in his fields.
Now you would think picking rocks year after year from a field would, over time, eliminate the rocks. On the contrary, it seemed that every year there were even more rocks that must have migrated up from the depths of the earth. To this day, if I never pick another rock again, it will be too soon.
I must admit that it builds character. I think that if I ever have to teach my son a lesson about hard work and perseverance, I’ll have him pick rocks.
Picking rocks, of course, is not the only difficult job on a farm. Baling hay, unquestionably, is difficult work. Most guys who have grown up in farm country have had the pleasure of baling the hay, loading it on a wagon and then unloading the hay into a barn.
It is hot and dusty, and the dry, stemmy grass makes your forearms look like hamburger after tossing only a few bales. Many farms have taken to baling, at least a portion of their hay, into large round or large square bales. It saves a lot of work, but you lose the character-building aspect of stacking the 40-pound bales in a hot barn in August.
I learned firsthand recently that building fence is perhaps one of the most demanding jobs on the farm. As many of you may have read in a previous column, my wife is now a goat farmer. In order to prevent the goats from wandering off, and also to prevent the coyotes from eating the goats, we needed a fence.
I recently fenced in about two acres. In fact, the fence isn’t complete; only the posts are in. But the posts have to be the most difficult part. At least I hope so.
I was able to borrow a post pounder from a friend of mine. The post pounder, as its name implies, pounds the post into the ground using the hydraulics from a tractor. But the person running the pounder can take quite a beating. Fifty-pound locust posts need to be pounded over and over again to set them 2 1/2 feet in the ground, below the frost line.
My dad helped me set the posts one afternoon. He remarked to me several times how much work the post pounder saved. When he was a kid, he used to set posts with a shovel and post hole digger. Ouch, my shoulders hurt just thinking about it.
The day after setting the posts, my arms hurt so bad that it was difficult to do my job. I wondered aloud to the farmer from whom I bought the posts how difficult I thought it would be to fence 100 acres. Of course, he shared with me that when he was a lad, they used to pound them in the ground with a 16-pound post maul while standing on the back of a wagon.
Yeah, right — and he used to walk five miles to school, in the snow, wearing a burlap sack for a coat while going uphill both ways. I expressed my disbelief and he assured me that in fact it was the truth.
I told him that I would have sold the cows before I did that. Wow.
Now, as I drive from farm to farm, I pay close attention to all of the fence posts in the ground. I wonder how many of them have been pounded in with a 16-pound maul or dug with a shovel. Probably more of them than I wish to admit.
by Dr. Bill Croushore, August, 2012
The middle of summer is prime time for a coccidiosis outbreak in both cattle and small ruminants. Coccidiosis is the disease caused by coccidia- a parasite that infects most mammals. Unlike worms, it is a single celled parasite. And Unlike bacteria and viruses, it has a definitive life cycle. Coccidia is known to be species specific, meaning that bovine coccidia can only affect cattle and no other species like poultry, swine, sheep or goats. Chicken coccidia cannot make cattle sick and vice versa.
Coccidia causes diarrhea, mainly in younger animals since immunity does develop after infection. The diarrhea can range from mild and self-limiting to severe with blood in the manure and life-threatening dehydration. It can also become chronic causing emaciation and general debilitation.
Some of the worst outbreaks in calves I’ve seen have come in the summer, presumably because as the grazing season progresses, pasture contamination of the infectious coccidia parasite increases. Coccidiosis is spread by the fecal oral route. Infected animals shed the parasite in their manure causing contamination of the pasture, feed or bedding. Once an uninfected animal eats contaminated feed or even bedding, infection ensues. Diagnosis of the infection is made by fecal exam.
Once coccidia eggs are shed in the manure, it takes a couple of weeks for them to mature in the environment before they are infective to another animal. This affords us an opportunity to prevent infection in confined animals by removing contaminated bedding frequently in order to reduce the parasite load in the environment. I often tell clients that if there was just one thing they could do to control and prevent an outbreak, it is to strip the bedding in all pens weekly.
Fortunately, there is more than one thing that can be done to prevent an outbreak. I should distinguish between trying to prevent an outbreak of clinical disease and prevent infection. It is unrealistic to expect to prevent infection of coccidiosis. All animals will get infected but few, if any, of them should get sick. Management practices center around preventing the actual clinical disease.
In addition to frequent manure removal in confined livestock, stocking density of pastured animals should not exceed pasture capacity. The risk of coccidia infection increases as the animals graze closer to the dirt. In other words, the shorter the pasture is, the higher the risk. If pasture capacity is exceeded, feed supplementation will not only reduce ingestion of the infectious agent, it will also elevate the plane of nutrition of the animal. In turn the animals’ immune system will be stronger and more likely to keep an infection from causing disease.
There are feed additives that prevent some degree of shedding of the coccidia parasite, thereby reducing exposure to uninfected animals. Called coccidiostats, Decoquinate (Deccox™), monensin (Rumensin™) and lasalocid (Bovatec™) prevent the shedding of the parasite in the manure. They are considered prevention, as they do not treat active infections. These agents are effective, but they are not a silver bullet. Used alone without manure removal, in my opinion, is ineffective. Some oral sulfa-type antibiotics have been used as treatments, but their use is limited. More commonly, amprolium (Corid™) is used as a treatment for sick animals. It can be used as a drench for individual animals, or more commonly as a water or feed additive. It is quite effective at treating clinical infection if proper supportive care is also given to the animal. Since many animals I see with the clinical disease are quite sick, fluid and electrolyte treatment and also antibiotic treatment are usually necessary.
Coccidiosis, like most infectious diseases, is exacerbated by high stocking density and poor nutrition. All of the coccidiostats or treatments in the world won’t compensate for ever increasing parasite loads in the environment. They are effective tools, but prevention should always be centered on preventing the ingestion of the infective parasite. Like anything else, an ounce of prevention is worth a pound of cure.
Dr. Croushore is a veterinarian with White Oak Veterinary Clinic in Berlin, and services farms in Somerset, Bedford, Westmoreland and Fayette counties. If you have a question for the veterinarian, send it to firstname.lastname@example.org
byDr. Bill Croushore
My profession seems to always be in the midst of a rather painful transition and sometimes it can be difficult to watch. There is a new transition among those of us that practice predominantly on livestock, particularly food animals. This change is essentially in the way we practice. The shift is in focus from treating sick animals to preventative medicine.
As farms have consolidated, many of the treatments are now performed by the farmer or the farm’s employees. Farmers and herdsmen have become quite proficient at both recognizing and treating common diseases in cattle. I’ve heard the stories from some of my more seasoned colleagues about the phone starting to ring at 5 AM for sick cows in the glory days. Many of the calls would be for down cows suffering from milk fever. Some days would see multiple cases of milk fever on the book before the office even opened.
Treating milk fever in dairy cattle most of the time is pretty straightforward. After finding a vein, stick a needle in it and infuse about a pint of calcium solution- job done. While it wasn’t in the best interest of their job security, veterinarians began taking on the task teaching farmers how to hit a vein and treat their own cases.
I rarely get to treat a typical milk fever anymore since essentially all of our clients have become good at sticking a needle in a jugular vein. I do get to treat quite a number of atypical milk fever cases that don’t respond to calcium treatment. Many of these cases never get up. There are some rules for dealing with these unresponsive down cows. First, have your veterinarian examine the cow for other conditions. Diseases such as cancer, injuries and infections can all down mimic milk fevers. And don’t rely on cold ears as a sign of milk fever. Just about anything that can make a cow sick can make her ears feel cold to the touch.
Second, determine if she is down truly because of milk fever. Milk fever happens when the cow, around the time of calving, pools much of her blood calcium, phosphorus and magnesium into her milk. If these minerals aren’t replaced in the blood from the bone quickly enough, the blood levels fall below a critical threshold and severe weakness is the result. Before treating with calcium, collect a blood sample into a red top collection tube. If the cow doesn’t get up after treatment, have the blood analyzed for calcium, magnesium and phosphorus.
If phosphorus is low, don’t count on the phosphorus in the Cal Phos bottle to fix it. It is in the form of phosphite and is unavailable to the cow. It is only in the bottle as a buffer. I treat all low phosphorus cows with 8 ounces of oral monosodium phosphate. Once treated, it takes a couple of hours for the phosphorus to be absorbed into her bloodstream. In fact, if a cow doesn’t get up after an intravenous bottle of calcium, a dose of oral phosphorus is probably indicated.
Third, make sure the cow is on good footing. A solid bedded manure pack or outside on the ground is ideal. Concrete is the worst. Move unresponsive cows from concrete using a “boat.” A boat can be constructed of something as simple as a sheet of plywood. Never drag the cow; always drag the boat.
Fourth, don’t push a cow to get up. If she continuously tries to get up unsuccessfully, she will wear herself out and an injury or severe muscle damage will be the likely result. Poke or use the hot shot only a couple of times and let her rest. Flip her from side to side at least every 6 hours to prevent downer muscle swelling.
Hip lifts may be useful under certain conditions. If the cow isn’t too heavy and is almost able to get up on her own, it may be of value. If the down cow isn’t willing to try to stand or has poor footing, hip lifts may do more harm than good. If you lift a cow and she just hangs, let her down. Hanging will definitely make her worse.
If a float tank is available and she still isn’t up, consider floating the cow. There seems to be some factors that favor success with the float tank. If the cow has an appetite and she is willing to try to stand, a float may be successful. If she has no appetite and doesn’t want to try to stand, she has a poor prognosis.
The appetite and willingness to try are good prognostic indicators regardless if the cow is floated or not. Don’t be discouraged if she is still down for even several days. We’ve all heard of those cows that haven’t stood for even a couple of weeks that eventually decide to get up.
by Dr. Bill Croushore
For the dairy farmer, the word “twin” may as well be a cuss word. In fact, it is a four letter word, isn’t it? But seriously, few farmers would ever wish that on any of their cows. One might think that twins is two for the price of one, but we all know that the complications of a twin pregnancy make it a net loser for the farmer and the cow.
First of all, many twin pregnancies never make it to full term and those that do are usually delivered early. Having had the benefit of using a portable ultrasound to do fertility checks in dairy cows for the past ten years, I see first-hand just how often that twin pregnancies end up dead before 60 days gestation. With the ultrasound, it is pretty easy to accurately diagnose most cows with twins, although clients never fail to inform me whenever I miss one.
In fact, I remember distinctly one cow that I didn’t miss diagnosing a twin pregnancy. I did, however, miss the triplet. That cow, after she had delivered the calves, had one complication after another until she finally died. Now, I routinely don’t stop counting until I am satisfied that I counted all the visible embryos. I diagnose triplets on about 5 cows a year.
Complications from twin pregnancies include late embryonic death and spontaneous abortion before calving. After calving, common complications include retained placenta, ketosis, twisted stomach, poor body condition and infertility. Preventing these complications first involves diagnosis while the cow is still pregnant.
There are, fortunately, several useful tools that can be used if we know the cow is pregnant with twins. Early dry off is probably the most widely used tool because it doesn’t require any special action. It does, however, require that the cow with twins be flagged somehow for early dry off. Anecdotally, it seems that cows benefit from the extra 2 weeks or so of dry period. In addition, it is not uncommon for the cow carrying twins to deliver 2 weeks early so the “early” dry off many times is actually just enough time.
Some dairies that feed a close up dry cow group will dry off the cow carrying twins directly into the close up group. The ration is usually a little higher in energy and protein, arguably a better fit for the cow carrying twins.
Some have taken more dramatic steps to prevent complications with twin pregnancies. When I make a diagnosis of twins, it is not uncommon for some farmers to abort the pregnancy and start over. As a rule of thumb, if twin pregnancies result in a high rate of complications on a farm, including displaced abomasum and death, it is probably a good idea to abort cows carrying twins and accept the risk of getting her pregnant again. Even if the cow doesn’t re-breed, a beef check for a big, fat repro cull is much more palatable than a dead cow. If, however, cows carrying twins respond well to early dry off and have few complications, then aborting pregnancies is probably not a good strategy.
In some cases, one of the pregnancies may be able to be eliminated. Between 28 and about 42 days, if twins are diagnosed as one in each horn of the uterus, one of the embryos can be crushed. There is about a 60% or so chance that the other twin will make it to full term. The chances for maintaining the pregnancy decrease as the pregnancy becomes more advanced at the time of reduction. If both of the embryos reside in the same horn of the uterus, it is very unlikely that the cow will maintain the pregnancy in the event that one of the embryos is pinched.
I often get asked about the likelihood of a heifer calf being born a freemartin after reducing the other twin pregnancy. Theoretically it is possible, although, to my knowledge, it has never been documented. I do recommend testing heifer calves born after reducing a twin.
Twins don’t have to be a death sentence for the cow, but early diagnosis is a big help in preventing many complications that go along with twin pregnancies. The first step involves diagnosis and good recordkeeping is essential. Dramatic steps are possible on farms where cows with twins perform poorly that improve outcomes in cows carrying twins.
by Dr. Bill Croushore
Soon, winter will make its unwelcome return and with it, difficult challenges when it comes to raising calves. After a reprieve last year from a couple of exceptionally harsh winters in a row, most people expect the cold and snow to return again with a vengeance. If it does, you might want to consider these factors for the sake of your calves.
Experience tells me that there are 2 major things that need to be done to wean a healthy calf in the winter. Having and following a sound colostrum plan is first and foremost. Colostrum is the first milk produced by the cow and is necessary for the calf’s immune system to function properly. The positive effects of colostrum are felt by the calf well past the time she is weaned. Conversely, the negative effects from the lack of adequate colostrum intake are likewise felt well past weaning.
All calves are born with an incompetent immune system. Without the priming immunity the calf receives from colostrum, the newborn is susceptible to a host of infectious diseases.
It is well accepted that larger calves like the Holstein require a gallon of colostrum at birth in order to achieve a minimum level of protection. The high volume is necessary because colostrum from dairy cows contain a lower concentration of antibodies (proteins that help prime the immune system) than beef cattle. In most cases, a full gallon of colostrum at birth will give adequate protection to the calf. Jersey calves need at least 2 to 3 quarts at first feeding.
Some calves will drink the whole gallon of colostrum on their own, but many will not. In most cases, I recommend that calves be given the entire gallon through an esophageal feeder tube. Don’t give the calf the opportunity to turn down that last quart; just tube it.
Yes, if calves get a full gallon of colostrum at birth, they might get a touch of diarrhea the next day. Colostrum has a laxative effect, which actually comes in quite handy for the calf who is trying to expel that nasty, sticky meconium. Don’t concern yourself with a little bit of milk scours but recognize that a gallon of colostrum is going to help prevent that bad case of E. coli diarrhea.
There are about as many ways of feeding colostrum as there are farms. I have seen colostrum fed as fresh, chilled, pooled, frozen and even colostrum replacer. The undisputed best is fresh and here’s why. Fresh colostrum, since it doesn’t have to be stored for any length of time, doesn’t overgrow with bacteria. Bacterial overgrowth in colostrum can be a death sentence for a calf. The same mechanism that allows for antibodies to be absorbed intact into the bloodstream from the calf’s gut also allows bacteria to be absorbed. Bacteria in the bloodstream of a baby calf is bad news.
Even if colostrum is chilled or frozen, it doesn’t mean that the bacteria don’t have time to multiply. The capacity of the refrigerator or freezer to quickly chill and the volume that is to be chilled or frozen can allow much of the colostrum to remain warm for hours. That’s plenty of time for the logarithmic growth of bacteria to occur. Under warm conditions, bacteria can double in population roughly every 20-30 minutes. This means that in 8 hours, good quality colostrum can have a bacterial population that exceeds 2 million bacteria per milliliter. That’s more than enough challenge to kill a calf.
Fresh colostrum also contains white blood cells from the mother that impart “memory” to the calf’s “uneducated” immune system. These white blood cells act somewhat like a vaccine to prime the calf’s immune system to respond to a pathogen quicker than it would be able to without them. This effect is lost when colostrum is stored or when a replacer is fed.
I have just a couple of things to say about colostrum replacers. First, if you have a colostrum replacer product, make sure it is indeed a replacer and not a supplement. Replacers must contain at least 120 grams of immunoglobulins, or antibodies, to have a minimum of effectiveness. If they contain less, they are only supplements and won’t impart adequate protection to the calf. Second, they shouldn’t be used routinely but only as a last resort when fresh colostrum is unavailable. Even colostrum replacers, while convenient and biosecure, do not give adequate protection to fully one-half of the calves that receive it.
In addition to its laxative effect and immune stimulating properties, colostrum is also loaded with energy and vitamins that can give that calf a great start in life. This brings me to the second major thing that can get a calf through the winter- adequate nutrition to stay warm. That will be the topic for next month.
There are 2 pillars of growing healthy calves in the winter time. I wrote about the first pillar, colostrum management, last month and this article will explore the other pillar- nutrition.
Keeping calves on an adequate plane of nutrition has always been recognized as critically important when it comes to the health of the calf. New research, however, is suggesting that what we used to think of as adequate may indeed not be good enough.
Dairy farmers have for a long time raised replacement calves as inexpensively as could be done and still end up with a strong, productive cow. It is understandable considering replacement rearing costs may contribute around 20% or more of total expenditures on a dairy. As replacements generate no income for the farm until after they freshen, keeping costs to a minimum seems like a good idea, especially since margins are always tight.
Feeding baby calves on milk replacer is obviously one of the most costly times in a replacement heifer’s life. The philosophy of feeding milk replacer has traditionally focused on giving just enough to maintain body weight and count on starter grain to contribute to weight gain once the calf begins to consume it. The “just enough” point was typically thought to be 4 quarts of a 20% protein and 20% fat (20/20) milk replacer divided into 2 feedings per day. That is equal to a pound of dry milk powder a day. In the winter, as we have all seen with our own eyes, that just isn’t enough for the calf to maintain her weight without substantial starter consumption. Since starter intake is insignificant before 2 weeks of age in most calves, the result is weight loss in the winter months while the calf burns calories to stay warm. To compound the problem, the period before 2 weeks old is when the calf is most susceptible to infections that cause diarrhea. Cold temperatures, inadequate intake and a viral challenge is an invitation for the calf to meet with the grim reaper.
It is well recognized that 2 quarts of 20/20 milk replacer 3 times a day in the winter, while still not ideal, will get a lot of these calves over the hump until their starter intake ramps up. But there are much better strategies than that.
First consider the environment the calf lives in. It doesn’t matter if the calf is in a condo, hutch or a calf barn; she needs to be kept clean and dry. Provide lots of bedding so she can curl up and “nest” to insulate herself from the cold temperatures. Keep a draft off the calf, but allow good ventilation.
A calf blanket is surprisingly effective in adding a little extra insulation for the calf. Mom always told us to dress in layers in the winter and the same holds true for the calf. A layer of dry fur underneath a calf blanket makes the calf comfy when the mercury drops.
I always harp on our tie-stall clients when it gets too warm in the stall barn. Cows love temperatures around 30 to 50 degrees Fahrenheit, but calves get a chill. The difference is the functional rumen. That rumen puts out a lot of heat and calves aren’t ruminating yet. That extra heat allows the cow to enjoy temperatures that would make a calf shiver.
Another trick is to encourage the calf to eat more starter grain. One way, obviously, is to make it available to her once she is a week old. Second is to offer free choice water from day 1. She won’t really drink significant quantities until she is at least a week old, but she will play with it. It is well accepted that calves with access to free choice water will consume significantly more starter grain than calves without. Try to keep a partition between the water and grain bucket since calves are slobs, yet they prefer to drink clean water. Offer warm water in the winter but not too hot or the calf will scald her throat.
Finally, consider the content of the milk replacer and the calf starter. Milk replacers that are higher than 20% in protein allow for significantly more growth than the conventional replacers. Whole milk contains somewhere around 27-30% protein and milk replacers that mirror whole milk do result in healthier calves. Starter grain protein concentration should be at least 20%.
I started off this article lamenting the fact that it is expensive to feed baby calves and here I am advocating that the process be even more expensive. Indeed, feeding more expensive milk replacer and higher protein starter grain will cost more. But the payoff will be in 2 areas. First, fewer sick calves will result in less treatment costs and fewer dead calves. Dead calves are very expensive. Second, there is ample evidence that feeding calves on a higher plane of nutrition in the first 2 months of life result in substantially higher milk production in their first lactation. I’ll expand on that idea next month.
Last month I wrote about the increased caloric requirements of the dairy calf in cold weather. It has long been accepted that during times of cold stress, calves must be fed at least an extra feeding of milk daily or they will lose weight. But what about the rest of the year; how will calves benefit from extra nutrition? And how will feeding calves better impact the bottom line of the dairy?
Let me discuss the benefits to the dairy calf first of all. Consider how we traditionally fed the dairy calf and how it compares to a beef calf. Dairy calves traditionally get 2 milk feedings per day while beef calves take around 10 feedings per day. Dairy calves traditionally get 1 gallon of milk per day, but the beef calf gets about 2.5 gallons a day. The milk replacer that a dairy calf gets contains about 20 percent protein and 20 percent fat (20/20.) The beef calf’s mama makes milk that is about 27% protein and 30% fat. The traditionally fed dairy calf might gain about a pound a day once it begins to consume some starter while the beef calf should gain at least 2 pounds a day on milk alone. Now I recognize that dairy calves and beef calves might as well be different species since they are so different, but if you fed a dairy calf the same way beef calves are fed by their mama, they would grow just as fast as a beef calf. Let’s look at the mortality rates between beef and dairy calves. According to NAHMS data from 1997 and 2007, beef calf mortality from 1 day of age until weaning (at 270 days) was 2.3%. Dairy calf mortality from 2 days old until weaning (typically 60 days) was 7.8%. Numbers like that kind of make you take notice, right?
Obviously, nutrition can’t be implicated in all of the difference since beef calves are with mama on the pasture and dairy calves are not with mama and are confined to a hutch or condo. But my experience tells me that nutrition does play a huge role. The more a calf is fed, the stronger she is and the stronger her immune system is. Many times I have seen dairy calves living in an apparently clean environment, yet the many of them were sick from either pneumonia or diarrhea. On the other hand, I have also seen calves that were fed on a high plane of nutrition that were able to avoid the same diseases despite many environmental challenges. Nutrition obviously impacts the immune system and its ability to fight off infectious disease.
There are other benefits to feeding calves well that are harder to see and even more difficult to measure. There are multiple studies that demonstrate between 1,000 lb and 3,000 lb milk production advantage in first-calf heifers fed a high plane of nutrition until weaning compared to calves fed conventionally. Recognize that the calves were only fed differently until weaning in these studies yet there were still dramatic increases in milk production for the well fed calves.
At first glance, I would agree that it is expensive to feed calves more milk replacer since, pound for pound, high quality milk replacer is the most expensive part of their diet. But after taking into account the efficiency of conversion of milk replacer, it becomes easy to understand why it makes sense to feed more of it.
Efficiency of conversion, or feed efficiency, refers to the percentage of intake that results in weight gain for the animal. A conventional 20/20 milk replacer diet has a feed conversion of about .37. A calf fed 2.5 gallons a day of a high quality milk replacer will have a feed conversion of .78. But how does that compare economically? Cost of milk replacer per pound of gain on a calf fed 1.5 gallons of typical milk replacer a day is about $4.58 per day. Cost per pound of gain of a calf fed 2.5 gallons of a high protein milk replacer is about $2.26. The reason for this is once you meet the maintenance requirements (calories required just to stay alive) for the calf, everything else it eats goes to gain. The more she eats, the cheaper the gain.
Unfortunately, it’s not as simple as putting 5 quarts in front of the calf twice a day. Feeding this much milk would require at least 3 feedings a day and some individual attention since milk intake should increase gradually as the calf grows. Strict attention to detail must be adhered to when mixing the milk replacer. Most problems arise from poor hygiene, or improper temperature or concentration of the final mixture.
Faster growth allows for heifers to have better frame, reach breeding size earlier and freshen sooner. She enters the milking string earlier and starts to pay you back. If you are in expansion mode, this would allow for faster growth and if you are not, it allows for quicker genetic improvement of the herd by accelerating voluntary cull rate. Either way, feeding calves better makes sense, and also dollars.
There was fear and trembling within the last couple of years about a report that the Food and Drug Administration (FDA) was about to embark on a new nationwide endeavor. The FDA was set to test bulk tank samples for the presence of residues from 30 or so available drugs commonly used in dairy cattle. There was talk of milk recalls and a national public relations disaster for the dairy industry. So what ever happened with that? Soon, I think that the cow manure is going to hit the barn fan. The FDA went ahead with the testing as planned; only outcry from the dairy industry caused them to do the testing without making public the results until all of the testing had been completed. The testing has since been completed and, as I write this, a final report has not yet been released but should be at the end of January.
I think that the results of the program are going to indicate that there will be a low number of herds that have shipped milk containing low level residues of common treatments in dairy cattle like tripelennamine (Recovr ) or flunixin (Banamine.) They will probably find some low levels of non-approved antibiotics in a few samples. Hopefully, I’m wrong, but if I’m not, get ready for some unwanted media attention.
We have addressed this topic with our dairy clients in the past and here are some of the things we recommended to insulate yourself. First of all and most importantly, do the right thing. Do not ship milk from cows that are treated with anything before the withhold time is up. We probably would all agree that milk from a cow treated with some Recovr diluted in a bulk tank does not render the milk any less wholesome. But in reality, the dairy consuming public has the expectation that their milk and dairy products are free from all drug residues and otherwise not adulterated. We don’t really want to have that debate- we will lose all day.
Keep treatment records. This is a big, fat, hairy deal. If you treat a cow with antibiotics, record it, along with the cow’s identification, the dosage, what you’re treating for and the milk and meat withholding. These records need to be kept and maintained in the unlikely event that you inadvertently ship a cow with a residue or even a hot load of milk. The lack of treatment records is a big red flag to the folks that do the follow up investigation.
I don’t care if you can keep track of who is treated in your head or not. Not keeping any treatment records is not only an accident waiting to happen, it’s a train wreck waiting to happen. You can download some really nice recording forms at nationaldairyfarm.com. If you don’t have a computer or printer, your veterinarian will gladly print you some copies.
Don’t give antibiotics or other medicines indiscriminately. This is less of an issue today than it was some years ago, presumably because of the high cost of antibiotics and long milk withhold periods. Our largest challenge today is without doubt flunixin (Banamine.) I, personally, have come to question the utility of flunixin in dairy cows except in certain situations like toxemia or high fever. Because it has to be given intravenously, without exception, its proper use is limited to those who can confidently hit a vein.
Get ready for expanded bulk tank testing and zero tolerance from both regulators and consumers. We have to remember that our customers demand the very best and we have to be prepared to provide them with it without excuses. American farmers have led the world in both food quality and quantity and there’s no reason that tomorrow should be any different.
When it comes to raising replacement heifers on a dairy, there are some duties that just can’t be avoided. Dehorning calves is one of these duties. Okay, I guess technically you could raise a cow with horns, but we all know what a bad idea that is.
In fact, sometimes we luck out and a calf ends up being born polled. In that case, obviously we don’t have to go through the process of dehorning her. I get asked periodically why farmers don’t breed for polled dairy cattle and I guess the answer must be that there is no compelling economic incentive to do so. The cost to dehorn a calf is far less than the potential lifetime genetic merit losses of selecting primarily on the basis of polledness.
That being said, there are expensive and inexpensive ways to dehorn a calf. The expensive way is to wait until the calf is a yearling heifer, crowd her behind a gate and chunk them off with the antique keystone dehorners. Granted, you might not lose any money out of pocket, but how much time does that take? How much weight does the heifer lose over the next several days as she recovers from the pain and blood loss?
The inexpensive way is to dehorn the calf before she is weaned. And if you really want to do it right, learn how to do a nerve block so the calf doesn’t feel it and never misses a meal. Here’s how I strongly encourage all of our clients to dehorn. At least once a month, routinely, all calves older than 2 weeks on the farm that haven’t already been dehorned should be done. I wait until they are 2 weeks old because it is at this point that their susceptibility to neonatal diarrhea (calf scours) becomes pretty low.
As for the local anesthesia, I always, without exception, give a local nerve block called a cornual block, prior to dehorning the baby calf. The technique is surprisingly very easy. So easy, in fact, that I can teach a client to do it in one calf. Simply locate the outside corner of the calf’s eye and press your finger into the groove about 1 inch behind it. Deposit 3 milliliters of local anesthetic under the skin in that groove and wait a couple minutes for it to diffuse to the nerve. I like to numb all of the calves at once, then in the same order they were given the anesthetic, dehorn them. Injectable local anesthetics, like lidocaine, are prescription drugs so consult your veterinarian if you are interested in acquiring some to perform your own cornual blocks.
As for the actual procedure of dehorning, I prefer to use a butane powered hot iron. I like to allow the burner to get very hot, then locate the horn bud and apply a good bit of pressure with the hot iron. You know when the cornual blocks works because the calf doesn’t flinch after the iron is applied to her head. Occasionally, though, the calf lets me know that there is still some feeling there.
I burn through the skin all the way down to the skull. I don’t routinely apply anything to the wound as it will dry and granulate in a week or so no matter what you do to it. Infection rates are extremely low, most certainly under 1 in 1,000. I’ve introduced dozens of dairy farmers to this method and none of them have ever gone back to wrestling the calf and scooping out the horns. The calves don’t miss a meal and don’t experience any shrink. And best of all, it’s better for your bottom line.
What do you do when you have a cow that is springing with calf but over her due date? I get asked that question quite often and my answer is almost always an unequivocal “Induce her!”
The only reason I say my answer is almost always and not always is the not so rare case of a wrong breeding date. Since the cow has a 21 day estrous cycle, we can usually differentiate a cow that’s overdue from a cow 3 weeks away from delivering her calf.
But if a cow is indeed overdue, induction is certainly indicated. Once the cow reaches the last month of her pregnancy, the developing fetus will gain about a pound a day. Prolonging the gestation in a cow by ten days can take a 100 pound birth weight calf to a 110 pound calf. That can very well be the difference between an unassisted birth and a difficult calving with a dead calf. Even worse, a cesarean section or fetotomy may be the result.
Prolonged gestation is not the only indication for induction of delivery; there are several others. If a bigger than normal calf is expected based on the calving ease score of the sire, an induction may very well spare the cow and farmer a lot of grief. We all know that a cow doesn’t necessarily have to be overdue to have a large calf.
Many times a farmer is expected to be away from the farm for a few days around the time a particularly special cow is due or a special calf is to be born. In that case, induction is indicated to allow the cow to be assisted in the event that there is an abnormal fetal presentation or otherwise unusual complication. I have prescribed induction more than once for this reason.
Rarely, dairy cows may develop a condition known as pregnancy toxemia during the last month of gestation. This is basically a bad case of ketosis before she calves and can be potentially deadly for the cow. In my experience, pregnancy toxemia is usually secondary to some other disease, but one of the treatments is to deliver the calf in order to lessen the metabolic burden on the cow.
Occasionally, we see a cow that is unable to get up due to an injury yet she is pregnant and within a couple weeks of her due date. In this case, we can induce the cow to calve early to save the calf, and then humanely euthanize the cow after the calf has been delivered.
One of the more common reasons that I prescribe induction is severe udder edema. Dairy cows with udder edema that has the potential to cause breakdown of the median suspensory ligament should always be considered for induction. One of the side benefits of inducing cattle with severe udder edema is that dexamethasone, the drug that induces labor, also helps to reduce udder edema. Speaking of dexamethasone, it is the drug of choice for inducing labor in late gestation cattle. It will only work if the developing fetus is alive since it depends on hormonal changes brought about by the fetus and the placenta.
Dexamethasone is often given along with prostaglandin F2 alpha, not because it makes it work better, but it reduces the complication of retained placenta in induced cattle.
Many are reluctant to induce calving because of the risk of retained placenta and potential unthriftiness of the calf. It is true that induction does increase the risk of these complications, however so does a high birth weight resulting from prolonged gestation. Most farmers that have instituted induction protocols when indicated are quite pleased with the results.
It is generally regarded as safe for the fetus to induce labor up to 14 days prior to the due date. The more immature the calf is, the higher the risk of breathing complications and death. Another one of the side benefits of dexamethasone is that it promotes maturation of the fetal lungs immediately prior to delivery. Once the induction drugs are given, calving usually happens within 24 to 48 hours. Longer times are possible if induction is done more than a few weeks before the due date. The closer an animal is to her due date, the closer to 24 hours she will deliver. Both dexamethasone and prostaglandin F2 alpha are prescription medications so consult your veterinarian to see if induction of labor might be indicated in your herd.
Do you know what a paradigm is? I’ll give you a hint; it’s not 20 cents. (Pair of dime? Get it? Explain it to the person next to you.) A paradigm is a perception, or the filter through which we view the way things are done. Changing paradigms on a large scale has proven historically to be very difficult.
For example, in veterinary practice, the traditional paradigm has been to do pregnancy checking by manual palpation. About 10 years ago, the use of portable ultrasound for use on dairy farms began gaining traction, but its perceived expense precluded widespread use for pregnancy diagnosis. Eventually, it reached a tipping point once the true value was appreciated and has since become the standard of practice. It has become the new paradigm.
When it comes to raising calves, the current paradigm is to feed the calves just enough milk to maintain their weight and count on starter grain intake to account for the calories needed for gain. Since milk or milk replacer is the most expensive part of the calf’s ration, it would seem that this paradigm is the most economical. Many of us are beginning to wonder if that is really the case and I expect that paradigm also to change.
Animal agriculture is experiencing considerable change right now. Market forces are causing farmers to reevaluate everything. 5 years ago, $150/cwt feeder calves was a pipe dream. It is now the norm. The cost to raise a dairy replacement heifer exceeds her value as a springing heifer and has so for the past couple of years. This is unsustainable, but what will precipitate change?
I’d like to invite you to think about a different paradigm, or a different way of doing things. Currently there is a serious oversupply of replacement heifers available for dairy. The old way of raising all heifer calves born on the farm and selling the excess as springers for a profit are gone. The cost of raising them simply is higher than what the market will bear. We see this reflected in the price of baby heifer calves. I’ve heard market reports where the bull calves bring better money than the heifer calves.
I’m no ag-economist, but I think we all know what’s causing this. High feed prices coupled with the ability to use sexed semen to select for heifers allowed for both the excess number of springing heifers and the high cost to get them there. Where am I going with this? I smell a paradigm shift brewing.
But what about beef cross calves? These are fetching upwards of $200 per calf in some markets right now. In addition, 4 and 5 weight feeder calves are still bringing $150/cwt.
Many large dairies are evaluating their replacement heifer needs and breeding with female sorted semen to meet some of their needs. The necessary heifer inventory is calculated and conventional semen is used on the better genetics to produce the necessary replacements, but no more. Everything else gets bred to beef to make a more valuable calf. These calves can be sold at birth, sold as feeders or raised for freezer beef. Eventually, this might reduce the number of dairy heifer calves born and take a bite out of the surplus; or maybe not.
In fact, that is just the start of the possibilities that are available. With genomic technology available now that can predict a calf’s genetic merit and rank her against herd mates, some are picking out only the best calves to raise for replacements. The ones that aren’t needed are sold off young to reduce replacement feed cost. Genomics can also be used within a herd to identify potential embryo donors to further improve the genetic merit of the replacements. Using female sorted semen to produce female only embryos in an in vitro fertilization program further increases the number of cows and heifers that can carry beef cross calves. I see one day where beef cross calves are much more common than they are today. Since raising them takes time and space, which are limited commodities on all dairies, it won’t happen overnight. Eventually, an infrastructure will develop around buying these crossbred calves at birth which should further support their price. A niche market will eventually become the standard and another paradigm will be born.
Dr. Croushore is a veterinarian with White Oak Veterinary Clinic in Berlin, and services farms in Somerset, Bedford, Westmoreland and Fayette counties. If you have a question for the veterinarian, send it to email@example.com
I get asked frequently about doing a diagnostic work up for abortion in cattle. Unfortunately from both the veterinarian’s and farmer’s perspective, these can be quite unrewarding. Abortions are very costly and making the call to test or not to test isn’t always straightforward.
There has always been and will continue to be a certain acceptable level of abortions in cattle; call it background noise, if you will. Many of these are just due to chance and are not preventable. But the ones that really scare us are the infectious causes. They have the potential to be the most costly since they will often affect multiple animals. They are more than just noise.
In order to maximize the chances of making a diagnosis in an abortion, a post mortem exam must be done complete with samples being sent to the lab. In most cases, if the cause is infectious, a diagnosis can be made. If the cause is not infectious, then a definitive diagnosis is unlikely. An undiagnosed abortion is not necessarily bad, though, since ruling out an infectious cause is a good thing. But what do you do in the event that the abortion rate spikes in your herd? Here are a few things I try to keep in mind when confronted with this question. Do new abortions represent a significant increase over normal background abortions? Some herds will experience up to 2-3% abortion rate after 120 days gestation. Abortion rates that approach 5% are alarmingly high and deserve investigation.
If the decision is made to investigate, be prepared for surprising results. Rarely do we make a diagnosis after the first aborted fetus is sent in. Often, requires several post mortem examinations are required to make a diagnosis or rule out an infectious cause. Common infectious causes include, but are not limited to the following.
Leptospirosis. Commonly referred to as simply “lepto,” it is a bacterial infection that typically causes late term abortion. Early abortion and embryonic death may occur with some strains. Sources of the infection include stagnant water, deer and rodent populations and other cattle.
Neospora. This is a parasite vaguely similar to coccidia and causes abortion is 2 different ways. Cattle can become infected by eating feed contaminated by dog feces. Dogs can become infected by eating placenta or an aborted fetus infected with neospora. The infection only lasts for several weeks in the dog, but during that time there is the potential to infect a whole herd of cows if dog feces are inadvertently mixed into the ration. Abortions result within several weeks of the exposure.
Once a cow is infected, they will always harbor the parasite; and this is responsible for the second cause of neospora infection. A previously infected cow will either abort a pregnancy or transmit the infection to her calf. If she has a heifer calf, the calf will be born infected and will be a carrier. She will be at higher risk of aborting her first pregnancy. The risk of abortion decreases with subsequent pregnancies, but is not eliminated.
Bovine Viral Diarrhea Virus(BVD). As you can tell by its name, this is a virus. It is easily diagnosed if it is the cause of abortion and if you find it, you’d better be looking at other cattle in your herd. Other cattle are the source of infection and most often it is from an animal persistently infected with the virus. Infectious Bovine Rhinotracheitis(IBR). Also a virus, it causes late term abortions mainly in unvaccinated herds. Vaccination against it is almost entirely protective.
Salmonella. This bacteria is present on most dairies and is spread by fecal-oral contamination. We see the occasional abortion caused by salmonella and I suspect that there are many more that go undiagnosed.
Mold. The common mold, Aspergillus, is reported to cause abortions through contaminated feed. I have diagnosed this before, but it is somewhat rare. There are vaccines available for Lepto, BVD, IBR and Salmonella, but not for the others. In order for the vaccines to be effective, they have to be administered regularly.
In addition to infectious causes of abortion, there are also genetic and congenital causes specific to each breed. Nutritional causes are extremely rare since the developing fetus has first priority for nutrition, even at the expense of the mother’s health. Even with a post mortem exam, the cause of abortion will go undiagnosed about 75% of the time. And 100% of the time, if an investigation isn’t undertaken, the cause will go undiagnosed.
There are times that I am fascinated by the human psyche. In fact, this holds true most of the time. I was having a conversation with a client the other day about some related business matters and he pointed out something that was both profound and obvious that I had never considered. I learned that the female psyche is very good at following rules to the letter of the law and men are very good at following rules in the spirit of the law. In other words, women follow rules and men don’t. Well, admittedly it’s a little more complicated than that. My wife, who is obviously female, drives on the same roads as I do and looks at the same speed limit signs as I do. She sees 35 miles per hour on the sign and she drives 35 miles per hour. That’s the law. I see 35 miles per hour and I see that I should slow down so I don’t hit a pedestrian or cause an accident out of excessive speed. That’s the intent of the law. She follows the letter of the law while I follow the spirit of the law. If I could only convince her that a recipe is a rule… well, that’s a story for another day.
I think that the same is also true when it comes to protocols on the farm. Arguably, women make much better calf raisers than men because they follow the rules better. 8 ounces of powder to 2 quarts of warm water is a rule to women but more of a guideline to men. Calves like it much better when we follow the rules.
The topic of treatment protocols and drug residue avoidance is an area where everybody should follow the letter of the law and not just the spirit of the rule. Obviously, when it comes to milk and meat withholding times, the rules must be followed to the letter, not just the spirit, without exception. But when it comes to treatment protocols, how well do you follow them? Are there even written protocols on your farm?
Along the same line of written protocols are written treatment records. Written treatment records reduce the risk of inadvertently shipping a treated animal for beef. I suspect most small dairies do not have written protocols or records since one person is responsible for performing all treatments. If that is the case, here’s why you need written protocols and records and why they need to be followed.
The goal of treatment protocols is twofold. First, treat all animals in a way that maximizes cure rates and return to production in the most economical manner with treatments that are proven effective. Second, prevent any and all meat or milk residues by using treatments with established withdrawal times.
I know what you’re thinking, “I don’t need written protocols because I have them memorized, I treat all my animals myself and I follow all withhold times.” Well, if that’s the case you’re following the spirit of the law but not the letter. Treatment protocols are mandated on all dairies that use any medicines in an extra label fashion.
For example, use of the injectable antibiotic Naxcel (ceftiofur sodium) to treat a cow with cellulitis (infection of the soft tissue under the skin) is an extra label use. Its use for cellulitis is only allowed on the order of a veterinarian, either verbal or written in the form of a protocol. Its use in this manner in the absence of written or verbal orders is specifically prohibited. Written treatment records are also a requirement to enjoy the flexibility of extra label drug use. Again, I know that the farmers who read this probably can rattle off the birth date, sire, dam and every treatment ever given to your animals. You know who was treated with what and its withhold time. I surely don’t doubt that you follow the spirit of the law. But the letter of the law requires that you write down every treatment given to every animal, especially the extra label ones. Look at it as redundancy built into your system to ensure that a treated animal doesn’t get sold or a hot load of milk gets shipped.
Treatment protocols are easy to write; your herd veterinarian should be happy to oblige that request. Treatment records are just as easy. Either computerized or paper records take only a few seconds to complete. A little time spent now will pay off later in preventing the pain and hassle of dealing with a violative residue.
One of the least interesting, but arguably most important responsibilities that I have is the development of treatment protocols on dairies. It is not interesting because it is essentially a “one size fits all” approach to treating sick cows. Since the practice of medicine is said to be both art and science, treatment protocols replace all of the art with science. Admittedly, I’ve never been much into the arts.
Proper treatment protocols are necessary for a host of reasons. When developed by your herd veterinarian, they provide continuity of treatment while removing many of our natural biases. For example, if you don’t follow any consistent protocols, it’s difficult to objectively evaluate your success or failure.
You may treat one animal with a particular antibiotic and it gets better. For whatever reason, the next animal gets treated with a different antibiotic and the animal doesn’t get better. Is it the fault of the antibiotic or are there other circumstances that we don’t know that led to the treatment failure? It takes a lot of numbers before we can begin to get even a fuzzy picture about evaluating treatment failures or effectiveness. Protocols help us to get those numbers without bias.
Protocols are legally necessary to treat food animals in an extra label fashion. This is where many of our dairy clients’ eyes begin to glaze over. But pay attention, this is really important.
With every bottle of medicine there is labeling that spells out exactly how and for what the medicine can be used. If you treat an animal for a disease with a medicine that isn’t approved for that disease or with a dose that is different from what’s on the label, you have gone “off label.” You need a prescription to do that.
So, the next time you reach for that bottle of Penicillin and give 40ml to a cow for an infected uterus, you have gone off label. Unless your veterinarian intentionally told you to do that or he/she has given you a written protocol for it, it is specifically illegal.
But perhaps the most important reason for treatment protocols is effectiveness. Protocols are usually developed to keep things as simple as possible. When I develop them for different farms, they are usually the same. Simple does work.
I can cite numerous examples of how keeping it simple works. One well known example was written about by Malcolm Gladwell in his book, Blink. It was the story of how ER doctors in Chicago used either a simple strict protocol or their experience from medical training to determine which patients complaining of chest pain were admitted for a heart attack. Overwhelmingly, the patients admitted based on the protocol were more likely to be correct than the doctors’ decision based on experience.
The same happens when treating dairy cows. Realistically, about 90% of sick dairy cows are affected by only about 5 or 6 maladies. They are milk fever, mastitis, metritis, pneumonia, ketosis, twisted stomach or indigestion. None of the treatments for these diseases are intensive or complicated.
Adhering to simple treatment protocols for the majority of cases can also help reduce drug costs on a dairy. Before any antibiotic is given to a cow, usually the most expensive part of the treatment, her diagnosis should fit the parameters of the written protocol. It makes absolutely no sense to treat an animal with a $50 dose of antibiotic if she doesn’t need it, right?
Once the protocols are in place, beware of the dreaded “protocol drift.” This is where nobody follows the original protocols anymore but flies by the seat of their pants. Old habits return and money flows down the drain like dumped milk.
Don’t worry about withholding your favorite treatment from a sick cow; your favorite treatment probably doesn’t work. I say this knowing that many of my favorite treatments over the years have turned out to be a complete bust. Most of our patients will get better despite what we treat them with. With the exception of surgery, most treatments don’t necessarily reduce mortality as much as they hasten return to production.
So have your veterinarian produce some simple, evidence based, easy to follow treatment protocols for your farm. They will save you time and money, but only if you follow them.
Diseases and other abnormal conditions are rarely isolated events. Veterinarian types such as myself have a word to describe this phenomenon- multifactorial. In other words, there can be many factors at play in a disease.
Lameness is well known to be associated with sub-acute rumen acidosis. Shipping fever is known to be a product of poor air quality, stress and pathogenic bacteria and viruses. Displaced abomasum results from a combination of ketosis and ration factors.
A lesser known interaction between diseases is mastitis and infertility. While it isn’t as well known, it is all too real. The scientific evidence for a link between these two common problems on dairy herds is compelling.
There are numerous studies that find cows with mastitis are significantly less likely to become pregnant. The cause or causes for this interaction are still being worked out, but here are some possible explanations.
Some, but not all cows that develop mastitis will have a fever at some point during the course of the disease. Elevated body temperature is well known to cause embryo death and a fever during mastitis may well be a factor.
During any inflammatory event, including mastitis, the immune system produces chemical messengers called cytokines. These cytokines can affect body temperature or have interactions with hormones responsible for recognition and maintenance of pregnancy.
The bacteria that cause the mastitis may share some direct responsibility for this effect of mastitis on fertility. Mastitis caused by gram negative bacteria such as E. coli produce chemicals known as lipopolysaccharides. Researchers have shown these lipopolysaccharides to directly reduce embryo development independent of any other mechanism in the body.
During an udder infection with E. coli, some of the bacteria that contain the lipopolysaccharides or even just the lipopolysaccharides itself may be absorbed directly into the cow’s bloodstream. Once it’s in the circulation, it can travel to the uterus and disturb a developing embryo.
The effect of mastitis can linger as well. The pool of follicles that produce the egg to be fertilized is affected by lipopolysaccharides well into the future. Whatever the mechanism of causing reduced fertility in dairy cattle, control of mastitis is important. Not only can it affect reproduction, mastitis is well known to reduce milk production and increase involuntary culling.
Mastitis can be controlled in dairy cattle, but it requires that some basic rules be followed. Keep cows clean, dry and comfortable. Practice accepted udder prep procedures during milking. Maintain milking equipment and check vacuum levels and pulsator function on a regular basis. Treat clinical cases early to prevent them from becoming chronic and cull chronically infected animals. Run bulk tank cultures periodically to screen for contagious bacteria like Staph aureus and Mycoplasma.
Consult your veterinarian for specific advice in your herd as it pertains to udder health. As a bonus, you may well wind up with more pregnant cows.
Pathology was always a favorite subject of mine in veterinary school. This was where we developed the skill of opening up the dead animals to determine what killed them. Often the visible lesions, called gross lesions, were enough to give up the secret. But many times more, samples had to be collected, processed and sent to the lab for further testing.
The necropsy (analogous to the autopsy on a human) is not just an exercise for the veterinary student. Nor is it reserved for the big teaching hospitals with all of their advanced degrees. No, the necropsy should be a first line of defense in the event of unexplained livestock deaths on any farm.
Especially with any type of infectious outbreak or toxicosis, a timely necropsy can be the difference between more dead animals or ending the outbreak. But timing is important in more than one way. The veterinarian is well equipped to perform a necropsy in the field, including the collection of any relevant samples. But if too long of an interval elapses between the time of death and the collection of samples, the samples may be rendered useless. The temperature outside has a huge impact on the speed at which the samples degrade. The warmer the temperatures are, the faster the tissues decay. Freezing also has a negative impact on the samples since it destroys the cellular architecture. Generally, most necropsies should be done within 24 hours of death and sooner in the summer months.
Most necropsies are performed in a similar fashion. First, the abdominal and chest cavities are opened up to allow the veterinarian to visualize the contents. Once the organs are inspected for gross abnormalities, then samples are collected for the lab if a diagnosis has not yet been made. I like to collect samples in duplicate. First, I collect fresh tissue samples of the filter organs (liver, lung, kidney and spleen) so the lab can check for infectious agents, like bacteria, fungi or viruses. I ship these samples as they are but chilled so that nothing will interfere with the recovery of pathogens. I also sometimes collect another big chunk of fresh liver if I suspect toxicity.
Second, I collect smaller samples of tissue to be “fixed” in formalin. Formalin fixation preserves the cellular architecture of the samples. The lab will then slice the tissue into microscopic thin sections, then add some specific stains and look for signs of disease at the cellular level under a microscope. This part is called histopathology and often yields a diagnosis.
If the cause of death is infectious, most of the time a diagnosis can be made if the samples are in good shape. If the animal has been dead for too long, however, the effort may be futile.
Here’s a quick example of where a timely necropsy may save literally scores of animals on any given farm. There is an emerging infectious disease, mainly in dairy cows, caused by a bacterium called Bibersteinia trehalosi. It causes an untreatable, rapidly fatal pneumonia in cattle and is quite contagious. It is untreatable, but preventable with the proper vaccine. This vaccine, however, isn’t commonly used in dairy cows. The disease can be diagnosed with a necropsy if samples are sent to the lab. So when cows start dropping over dead, the sooner a necropsy gets done the sooner the outbreak can be stopped. The same can be said with any infectious disease, including diseases in calves, cows and abortions.
I suspect that the perceived cost of doing a necropsy scares some farmers off, but consider this. The cost is generally under several hundred dollars. What does it cost to replace just one cow? Getting that diagnosis early may save several animals from the compost pile.