Vet Column 3-8-10 |

Vet Column 3-8-10

David L. Morris, DVM, Ph.D.
Fort Collins, Colo.

As spring breeding season plans come into focus, issues of vaccination programs and boosters arise, particularly with heifers to be bred the first time. Whether it involves natural service or artificial insemination, optimizing the health status of replacement heifers pre-breeding reduces disease risk involving the vaccine(s) used.

Two land-grant university veterinary researchers recently offered some insights regarding immunology and generalized vaccine choices. Certainly, with the varied environments and circumstances associated with cattle operations, dairy or beef, consultation with your veterinarian to hone in on the specific vaccines that best apply to your operation is excellent advice.

Once a beef or dairy heifer reaches 4 to 5 months-of-age, her immune system is close to maturity. Occasionally, heifers that are 12 to 18 months-of-age can be immunologically naïve if they have not received immunizations previously. This is because the immune system may have less memory as a pre-breeding animal than as an older cow.

One of the reasons for vaccinating at younger ages and repeated at various intervals prior to first calving is to create sufficient memory so that booster immunizations can produce protective antibody quickly and optimally. On the other hand, too much vaccination can be detrimental. This may be more of a case when calves are less than 3-months-of-age.

It has been suggested that dairy heifers beginning at 3 to 4 months-of-age and beef heifers at 4 to 6 months-of-age should have received a BVDV, IBR, and Leptospira hardjo vaccine. Ideally, this would be repeated in two to three months. Other considerations would include brucellosis, Trichomonas foetus, Camyplobacter (vibrio), and J-5 bacterin (dairy). Again, these recommendations are general as factors such as commingling or exposure to other cattle, as well as use of natural service or artificial insemination can influence some of these recommendations.

If breeding time is near, concern should be directed to how far in advance of breeding will the vaccinations be administered. Vaccines, such as modified-IBR, can replicate within the ovary and be associated with decreased conception rates, if administered too close to breeding. If the animals have not been previously vaccinated, the first dose should be at least two months prior to breeding. If the animals have been previously vaccinated, at least a month before breeding is recommended. Also, some vaccines can induce an inflammatory response that has been associated with decreased conception rates if given too close to breeding.

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Always remember that vaccinating and immunizing can be two different things. Just because vaccines are given, it doesn’t necessarily assure that immunization will take place. It is well known that inadequate energy and protein in the diet can compromise the immune system and its ability to respond adequately. Similarly, crowding, commingling, and heat and cold stress are management factors that can compromise the immune response.

And don’t forget the trace minerals. Copper, selenium and zinc are important to producing a desirable immune response. Vitamin E is also helpful in pre-breeding heifer health programs.

The goal of pre-breeding heifer vaccination or immunization programs is to ensure the opportunity for heifers to develop colostral antibody levels that will help protect their calves throughout their reproductive life by creating immune memory. It’s too important not to consider developing a cost-effective, risk-based approach.