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Colostrum-derived immunity against calf respiratory viruses

Manuel Chamorro Published on 22 August 2014

An important factor in calfhood health is the presence of maternal antibodies in calf serum during the critical first few weeks of life for protection from disease.

One study shows that compared to maternal colostrum, feeding a lacteal-derived colostrum replacer provides a more uniform range of antibody titres to some common respiratory viruses affecting calves. Feeding a colostrum replacer may allow for better prediction of vaccination schedules and reduced incidence of disease in a herd.

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Bovine respiratory disease (BRD) is one of the most important diseases affecting cattle in North America and is an important cause of economic losses in cattle operations worldwide. It is estimated that economic losses due to morbidity and mortality associated with BRD in the beef industry in the U.S. can reach $800 to $900 million per year.

Viral respiratory pathogens such as bovine viral diarrhea virus 1 and 2 (BVDV 1 and BVDV 2), infectious bovine rhinotracheitis (IBR), bovine respiratory syncytial virus (BRSV) and parainfluenza-3 virus (PI3) play an important role in the pathogenesis of BRD due to their ability to impair the integrity of the upper respiratory tract, cause immunosuppression, promote secondary bacterial infection and cause acute clinical disease.

Antibodies against respiratory viruses transmitted through maternal colostrum protect calves against acute BRD, and calves with high-serum antibody titers against BVDV, IBR, BRSV and PI3 are protected against developing acute BRD at challenge with viral pathogens; however, as colostrum-derived immunity wanes, calves become susceptible to acute BRD.

The duration of colostrum-derived immunity against respiratory viruses depends directly on the amount of specific antibodies to BVDV, BHV-1, BRSV and PI3 ingested and absorbed from maternal colostrum. The higher the levels of antibody absorbed from colostrum, the longer the duration of the maternally derived immunity and the longer the protection against these pathogens.

Interestingly, a high variation in the initial serum levels of antibodies against respiratory viruses is observed in calves that receive maternal colostrum at birth.

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Usually proper amounts and quality of maternal colostrum provide enough immunoglobulins to prevent failure of passive transfer in newborn calves, but unfortunately, that does not always translate into transfer of adequate levels of virus-specific immunoglobulins.

This phenomenon leads to uncertainty and variability of the age at which calves will become susceptible to BVDV, BHV-1, BRSV and PI3 infection and makes the establishment of adequate vaccination programs more challenging ( Figure 1 ).

Calves susceptible to BVDV

Colostrum replacement products provide newborn calves with adequate amount of immunoglobulins and prevent failure of passive transfer when the availability and quality of maternal colostrum on the farm are limited.

In one of our recent studies, we compared the serum levels and the duration of BVDV 1, BVDV 2, BRSV, IBR and PI3V antibodies in calves fed maternal colostrum (MC) or a colostrum replacement (CR) at birth.

The results of this study demonstrated that calves that received CR had greater BVDV 1 and BVDV 2 serum antibody titers during the first months of life. Additionally, the levels and duration of immunity against BVDV, IBR, BRSV and PI3 were uniform and consistent in calves that received CR at birth.

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In contrast, calves that received MC demonstrated highly variable levels and duration of immunity against the same viruses, which resulted in shorter times to reach sero-negative status and to become susceptible to acute infection.

The greater variability in levels and duration of immunity observed in calves that received MC at birth could increase the risk of introduction of infectious pathogens such as BVDV, BRSV, BHV-1 and PI3V into the calf herd.

On the other hand, consistent levels and duration of immunity against respiratory viruses provided by colostrum replacement products reduce the risk of introduction of viral respiratory pathogens into the calf herd and facilitate prediction of optimum time to vaccination. PD

References omitted due to space but are available upon request. Click here to email an editor.

FIGURE 1
Proportion of calves that become susceptible to acute BVDV infection (AB titer < 1:32) per time period. A high percentage of calves fed maternal colostrum were susceptible to acute BVDV-2 infection in the pre-weaning period, whereas colostrum replacement calves were protected until 4-5 months of age and could potentially respond to vaccinations in a uniform way.

manuel chamorro

Manuel Chamorro
The Saskatoon Colostrum Company and Auburn University

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