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Priming the Calf Immune System for the Challenges Ahead (Jul 13, 2017)

By Justin Kieffer

Now that calving is completed, the days are longer, and the grass is growing (hopefully), it is time to start preparing for the weaning and eventual sale or feedlot finishing of your calf crop and development of your replacement females. Once the cow calf pairs have been kicked out to pasture in the spring, there is a tendency to put off or ignore the steps needed not only to set the feedlot calf up for success, but also to lay the groundwork for proper health for your new heifers.

Management techniques such as castration and dehorning should take place as soon as possible. Waiting too long to remove the testicles, either by banding or cutting, increases the risk of bleeding and infection, and knocks the calf off feed for an extended period of time. The smaller the calf, the less attached they are to their testicles. Removal of horns, if present, can be done at birth or shortly thereafter using caustic dehorning paste on the horn buds. If scooping of the horns is the method you employ, make sure to do this before the horns reach 2 inches in length to avoid having an open sinus cavity in the head, which is prone to infection and fly-strike. In both of these techniques, pain control for these procedures is highly recommended and easy to perform. This is critical both from a welfare perspective, and the added bonus of keeping the calf on feed during the healing process.

Vaccinations are also a critical aspect of calf prep that are often misunderstood or under-utilized. As you may know, when a calf hits the ground they have no immune globulin proteins circulating in their blood stream to help fight infections. All of their initial immune globulins come from the colostrum at the first feeding, which needs to take place ideally within the first six hours after birth. The ability of the calf to absorb immune globulins past 24 hours of age is almost zero. These proteins are made by the dam, and concentrated in colostrum prior to birth, this is why vaccination of pregnant cows is essential in providing immunity for the calf. Once the calf is up and nursing, those immune globulins provide immediate resistance to disease.

As the calf ages, the colostral immune globulin levels start to drop off over time, and are mostly gone by around 3-4 months of age. This is an important concept to understand for two reasons: First, giving the calf an injectable vaccine before this time frame means that any antigens for diseases you are vaccinating for (IBR, BRSV, PI3, etc.) will be neutralized by the immune globulins delivered in the colostrum. Essentially, if you have vaccinated the pregnant cow for those same diseases, and the calf nursed properly, there is no need to deliver those same vaccines to the calf prior to 4 months of age.

The second reason not to give an injectable vaccine before this time frame is that the calf’s immune system is not ready to see and react to the vaccine. It takes time for the white blood cells responsible for the development of a systemic immune response to learn their jobs and be able to react to invading bugs. One important exception to the use of vaccines in young calves is the use of intra-nasal vaccines. These vaccines provide a localized immunity in the nose very quickly, and are not interfered with by colostral immunity. This is why these vaccines can be given immediately after birth, and at any time in the production cycle safely and effectively.

Timing of vaccines is also imperative. For example, when the first round of a vaccine is given to a 5 month old steer calf, it takes time for the responsible white blood cells to find that vaccine and take it to the lymph nodes where antibodies can be produced. This process on average takes about 21 days. This is why most vaccines are labelled with directions indicating at least a one month wait before administering a booster shot. If we give the booster shot before the immune system has had time to create antibodies and a memory of the bug, we will not have that second strong immune response from the booster that provides superior protection.

Completion of these management techniques and vaccine protocols prior to the stress of weaning, comingling and transport will help you assemble a calf crop more resilient to disease challenges. Combined with a low stress weaning technique carried out 6 weeks prior to leaving the farm, this type of strategic planning for superior health provides a calf for which buyers will want to pay a premium. Consult with your herd veterinarian to design a vaccination and calf management plan that fits your type of operation.

Source: osu.edu


 
 
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