Vaccination Programs to Improve Calf Health

Background 

Developing vaccines is very costly. But what we can make the vaccines we already have work better? There is some evidence that “heterologous” vaccine protocols that use one kind of vaccine for the initial vaccination, and a different kind of vaccine for the booster (e.g. a modified live vaccine for the initial calfhood vaccination and a killed vaccine as the booster at weaning) may provide better immune protection than a “homologous” vaccine protocol that uses the same modified live vaccine (or same killed vaccine) for both the initial and booster vaccinations. 

Objectives

Provide tools that will decrease the risk of bovine respiratory disease (BRD) in calves and reduce the use of antimicrobials for prevention and treatment of BRD through:  

• Using a multiple viral challenge model to compare the disease sparing effect of heterologous and homologous vaccine protocols in a controlled study 

• A large-scale field study to compare the effectiveness of the protocols in reducing BRDC morbidity, mortality and the effect on average daily gain 

What they Did 

This team used different vaccines that both protect against infectious bovine rhinotracheitis (IBR), bovine respiratory syncytial virus (BRSV), parainfluenza virus (PI3), coronavirus and bovine viral diarrhea virus (BVD) Types 1 and 2. In the first trial, calves will be vaccinated with an intranasal modified live vaccine against BRSV, IBR, PI3 and coronavirus at birth. At branding, half were boosted with an injectable modified live vaccine and half with an injectable killed vaccine. At weaning they were challenged with BRSV, PI3 and coronavirus. Animal health measures (including lung scores) were recorded.  

A follow-up field trial compared the similar protocols in 1,000 commercial calves initially vaccinated with an intranasal MLV at birth or branding, and boosted at weaning using either an injectable modified live or injectable killed vaccine. The calves were followed through the feedlot, and health, treatment and mortality rates and performance was tracked. 

What they learned

Overall, 83 per cent of herds vaccinated their cows for BVD and IBR using either live or inactivated vaccines before the breeding season began, while the other 17 per cent did not.

Herds that were co-mingled during the breeding season had poorer reproductive performance, especially when cows weren’t vaccinated pre-breeding. Cows from herds that used community pastures were less likely to be pregnant in fall and were more likely to abort the next spring than cows from herds that didn’t use community pastures.

Vaccinated cows were more likely to get pregnant, especially in commingling situations. On community pastures, cows that had been vaccinated before the breeding season with either a live or inactivated vaccine against BVD and IBR were six times more likely to be pregnant in the fall than cows that had not been vaccinated. In fact, reproductive performance in commingled herds that had been vaccinated against BVD and IBR was the same as in herds that hadn’t been commingled at all.

Vaccinated cows were less likely to abort, especially in commingling situations. On community pastures, cows that had been vaccinated before the breeding season with either a live or inactivated vaccine against BVD and IBR were nearly four times less likely to abort than cows that had not been vaccinated.

Calves born to vaccinated cows were less likely to be treated before weaning. An upcoming paper from Dr. Waldner’s research team (Improving beef calf health: frequency of disease syndromes, uptake of management practices following calving, and potential for antimicrobial usage reduction in western Canadian herds) drew on information from 89 cow-calf producers participating in the Western Cow-Calf Surveillance Network. Although nearly all the herds vaccinated cows against BVD and IBR, only 29 per cent of the herds vaccinated their cows against BRD bacteria (Mannheimia, Histophilus and Pasteurella). In this study, herds that had not been vaccinated against BRD bacteria were more than eight times more likely to treat their calves for BRD between four months of age and weaning.

what does this mean

Your vaccination program will be particularly valuable insurance, especially if you end up sharing a breeding pasture with others. Annual booster vaccinations are the insurance premium. A 2019 report entitled Adoption Rates of Recommended Practices by Cow-Calf Operators in Canada indicated that over 25 per cent of Canadian cow-calf operations don’t vaccinate their cows for IBR and BVD before the breeding season. The most common reason for not vaccinating against these reproductive diseases was “I have a closed herd.” That’s pretty unlikely. Closed herds are exceedingly rare. Commingling doesn’t just happen on community pastures, forestry reserves and other grazing lease arrangements where different herds mix. Commingling also happens when new breeding stock (purchased or leased females, bulls or calves) enter the herd and when fences break or get jumped. Disease can also spread through nose-to-nose contact across fences.

Vaccination is far less costly than even a few more open cows or a few more abortions, and much less costly than a reproductive disaster, an abortion storm or a BRD wreck in next year’s calves. Talk to your veterinarian to make sure that your vaccination plans are still appropriate for this summer’s possible grazing scenarios.