Vaccinating pregnant cows: Scours vaccinations

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Pregnancy checking time represents an opportunity for producers to perform other procedures at the same time.  For some producers, vaccinating cows is on this list of tasks.  But just because it’s handy for us, will it work for the cow?  

There are two main reasons most producers vaccinate cows.  One of them is for infectious reproductive pathogens that can cause harm to the developing fetus.  The other is that of the calf scours complex, which includes vaccinations against neonatal diarrhea pathogens such as rotavirus, coronavirus, clostridial organisms and e. coli strains.  The other is for. 

Vaccination programs against calf scours have a unique goal.  Here we are attempting to raise the level of antibodies in the cow’s bloodstream so that when she starts manufacturing colostrum for her calf, a high concentration of those antibodies will be there in the colostrum when the calf nurses in those first hours of life. It’s an indirect way of providing immunity to the calf. 

Is preg-check time the best time to stimulate this immune response in a cow?  We know that a cow begins the process of moving antibodies from the bloodstream to the mammary tissue no sooner than about 5 weeks before she calves.  Her blood antibody level at that late stage of gestation is the determining factor in how much antibody is present in the colostrum. 

There is a wide variety of calf scour vaccines on the market, and each of them has different recommendations for vaccine timing.  Some are labeled to be given as early as 16 weeks prior to the expected calving date; others may require administration closer to calving.  Vaccine manufacturers base these recommendations on their product’s ability to show increased levels of antibody in colostrum when cows are vaccinated at those particular stages of gestation. 

There’s a great temptation by some producers to use these vaccines at pregnancy checking to take advantage of the obvious labor savings, but some basic immunology should be kept in mind.  If it takes 1-2 weeks for the cow’s body to show a peak response to the vaccine, this means the best time to stimulate this immunity would be no sooner than about 7 weeks prior to calving.  Later is better (up to a point) when using scours vaccines.

Does this mean that a scours vaccine given to cows too far ahead of calving is worthless?  No, not really.  But we would expect that, when compared to cows vaccinated later, those early-vaccinated animals would have a waning immune response by the time they start making colostrum, and therefore a lower concentration of antibodies for the calf. 

Calf scours is a disease complex that results from many factors, including overwhelming exposure to germs, environmental conditions, and poor colostrum uptake by calves.  It’s entirely possible that herds could vaccinate cows at a less-than-optimal time (or even not at all!) and still breeze through a calving season with no scouring calves.  These are likely to be herds that have a good handle on those other factors (low dystocia levels, clean calving areas, weather protection, etc.).  But for other herds, tweaking the timing of scours vaccination may help alleviate some of these problems.  This is a great time of year for producers to consult with their veterinarian about how best to use tools such as scours vaccine as part of a calf scours prevention plan.

Source: Russ Daly

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Todd Gunderson    
Cardston, Alberta  |  October, 20, 2012 at 07:25 PM

So Russ, how does the DOI facture into your figures? If my peak antibody levels plateau for anywhere close to 20 weeks from vaccination, then vaccinating at 16 weeks prior to the onset of calving would mean that a cow who calves 9 weeks into the calving window still should have protection right? (She would still have high levels of antibody 4 weeks into calving, which means that as long as she calves withing 5 weeks she should be good). Not all vaccines have the same DOI, so definitely this would make a difference. What are your thoughts on that?

Russ Daly, DVM    
SDSU, Brookings, SD  |  October, 24, 2012 at 03:48 PM

Todd, you are correct. Duration of immunity is very important when looking at these timing issues. As you state, we don't know information about duration of immunity for every vaccine. And in reality, even for those that publish that data, vaccines work differently in every animal. There is a lot more variability than we would like. One could make a case that the physiology of cow's colostrum formation may be more predictable than response to vaccine, especially when you throw in all the different vaccines that enter the picture. So you are correct with your calculations. But you have plugged in a 20-week DOI. That may in fact be accurate. But I would offer that using that same vaccine at 6 or 7 weeks pre-calving would result in better antibody levels in colostrum and higher levels later into calving than using that same vaccine at 16 weeks pre-calving. You could still vaccinate 16 weeks prior to calving in your case and get by just fine. But that depends on a lot of other factors too, like mentioned in the article. Is it worth it for producers to gather cows for a separate time through the chute in order to give scours vaccine later? For some, it sure might be (bad weather ahead, needing to calve in a confined area, etc. etc.). In other herds where exposure and stress is less, colostral antibody levels from cows vaccinated later might be just fine.

Gennifer Murillo    
Mesa, AZ  |  October, 07, 2013 at 03:26 PM

What is the route of administration for this vaccine? I am doing a paper for my Vet Tech degree and need a little additional information.

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