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Newsletter of Penn Dutch Cow Care October 2011

Hi Folks,

So, it’s getting time to bring the animals inside for the seasonal change towards winter at some point soon. But which animals are we talking about? Certainly the milking cows will be in more as we tend to give them the most attention. But what about the young stock? Often times we let the bred heifers stay outside with a place for them to bed down and be out of the elements and that’s good. But how about the younger heifers? Oftentimes people want to bring them back inside after the grazing season is done for some reason. But why? That fresh air they have been getting is so much better for them than stale barn air or shared barn air with the milking herd. As a rule, I would say that young stock should not come back into the barn until they freshen since they are at risk for pneumonia if stuck inside all winter with the older animals.

So should we vaccinate animals at this time of year? It’s a common practice to do so. In some ways it is admitting that the indoor living isn’t as good as the outdoors on pasture, right? Like I have come to realize, the best vaccination program is one that is based on fresh air, high forage diets and dry bedding and dry bedding and dry bedding. (That wasn’t a typing mistake.) At least that is for respiratory health. Another important way to prevent respiratory problems in stabled animals is to put them outside every day for as long as possible. This allows them to breathe in fresh air just as we like to every day. Remember that the cattle breeds we have are from northern climates and like temperatures between 20-50 degrees F (-5 to +10 C). There is no need to keep them in when it is 22ºF if the sun is shining, there is little wind and the footing is not slippery. On the other hand, the worst possible weather for cattle to be in is when it is raining and barely above freezing. They will lose body condition fast. If young stock are carrying an internal parasite burden, or if they have poor body condition due to not enough feed and energy intake, they will likely break with pneumonia. Young stock with such issues will also break with pneumonia when put inside and especially if the bedding becomes damp and they are in a cinder block or wooden building with windows high above them only. If this is unavoidable, then vaccinating with one of the intranasal vaccines is best as it gives quick protection (within a few days) and will last a few months. I have always liked the idea of the intranasal vaccines if only because they mimic the real way respiratory germs typically gain entrance to the body – through the nose. Otherwise, structures with excellent air movement just above the height of the animals but which allow no drafts at bedding level (such as curtain barns, hoop houses or large super hutches) are great for keeping weaned animals and bred heifers in.

Do we need to vaccinate if we are abiding by the “high forage diet, fresh air and dry bedding” rule? That depends on some factors. First, what do you want to vaccinate for? Is it the respiratory bugs mainly?  If so, read the above again.

If vaccinating is for reproductive bugs, then we may want to consider it, depending again on some factors. First, what kind of reproductive problems, if any, have been occurring? There will always be a few cows that don’t settle easily. What about cows called pregnant around day 35-40 and then come back into heat a month later? Or actual abortions seen – how many in what size herd and during what time span? In a 50 cow herd, it would not be unreasonable to see one spontaneous abortion over a year or maybe two if they are far apart. If you see 2-3 abortions in a 50 cow herd within a month or two, I would start wondering what is going on. Typically, cows that abort at 1-3 months pregnancy may be challenged by BVD, at 4-6 months pregnancy they may be challenged by BVD or Lepto and at 6-8 months pregnancy they may be challenged by Neospora. And if many cows are showing irregular heat cycles or perhaps have been bred but come back in heat not on a 21 day cycle, BVD could be an issue.

Testing of the aborted calf and two blood samples from the cow (at time of abortion and 3 weeks later) will give the best possible information from a lab. Or, if there are no abortions, but irregular heats or cows are not settling, then drawing blood from at least 10% of the animals in the herd (testing the problem animals) can reveal what the problem may be. While an aborted fetus is looked at under the microscope and samples are taken to identify any bugs that may be present, blood samples from cows are generally checked for antibodies to bugs. Antibodies to bugs like lepto, IBR, BVD and neospora reveal to what degree the cow’s immune system has responded to a challenge form those bugs. The results are presented as titers. The higher the titer, the more likely the bug causing the titer was involved with the problem. However, if you have a vaccinated herd, those results could be from the vaccine since vaccines mimic natural exposure and cause the animal’s immune system to respond. This is good for when the animals are truly exposed to the real bug, their immune system is ready to neutralize the challenge immediately. Looking at the titers of animals that haven’t been vaccinated in a number of years is very useful for results showing any high titers will be meaningful since it indicates that the animals have seen the real challenge by the bugs themselves and are reacting to them.

Be aware that trying to vaccinate your way out of a problem may or may not work. It probably is a reasonably good idea if Lepto hardjo is involved as that is difficult to get rid of it otherwise. But if BVD is floating around in a herd, vaccinating may give a false sense of security. This is because of a possible Persistently Infected (PI) BVD animal present. These animals are born with BVD and every moment they are alive they are breathing out, peeing out, manuring out, and coughing out live BVD particles into the environment which no vaccine can overcome. These animals must be identified and removed from the herd before any BVD vaccine will work to prevent any such future occurrence.

If vaccinating, using a modified live version is probably the best route for effective coverage. I have read that some immunologists say giving a modified live vaccine against the respiratory viruses at 6 months of age and then again a month before breeding age may give lasting immunity for life. But I would like to see further studies on that. However, if you think about it, if we get a tetanus vaccine, it is good for 10 years. If vaccinated for measles and mumps, the immunity is nearly life time. So why do people vaccinate cattle every year – probably because the box says so. Perhaps some studies need to be done for how long titers stay high from vaccines. (Don’t expect vaccine manufacturers to do the studies.)

But remember that the animals’ environment and feed play a much bigger part in staying healthy than vaccines. One thing to think about is animal concentration – what is the optimal number of animals to have for a certain size of land or barn? Now there’s a real question. The beautiful stone barns of the southeastern PA area were originally meant to house no more than probably 15 cows, their young stock, a few horses and a handful of pigs and chickens. Now they routinely house 40 cows, some young stock and a full team of horses. I think it only makes sense that when there is a high density of animals in one area, bugs/germs have it easier to “set up shop” in the animals there. That’s why routine massive vaccination programs have become so common place in modern agriculture – because of the high concentration of animals in one location, whether it is a 40-50 cow tie stall in a stone barn or a 400-500 cow free stall system. I’m not against vaccines but the best “vaccine” for farm animals will always be fresh air, dry bedding, high forage diets, sunshine and being outside.    

 

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