Last week's tip discussed an article in the The Veterinary Clinics of North America Food Animal Practice journal. In the March 2010 issue, in the article "Control, Management and Prevention of Bovine Respiratory Disease in Dairy Calves and Cows," authors Dr. Patrick Gorden and Dr. Paul Plummer of the Iowa State University College of Veterinary Medicine reviewed vaccine and management programs for young calves.
Relying heavily on an article published in the same journal in 2008 by Dr. Chris Chase and coworkers at South Dakota State University, these authors write: "Effective vaccine programs for young dairy calves are difficult to develop because of the complex nature of the immature immune system and the complexities of management systems where calves live."
In general, "traditional" vaccines are ineffective for young calves because colostrum immune system components received by the calf can interfere. Intranasal vaccines, however, aid development of immune system components on surfaces of respiratory linings (primarily in the nasal area). These vaccines offer a chance of reducing infectious organisms which may enter the calf's body.
However, little can be done to boost the calf's immune system response if the pathogen evades the barrier on the respiratory system linings. Thus, intranasal vaccines can be useful in young calves receiving adequate colostrum.
In his paper "Neonatal Immune Development in the Calf and Its Impact on Vaccine Response," Dr. Chase notes the dangers of "over immunization." Repeated administration of vaccines to calves can result in permanent suppression of the immune system, leading to the calf being more likely to become sick than if it had not been given any vaccine at all.
He also notes the earliest age at which a calf's immune system will respond positively to a vaccine varies by the type of vaccine and the pathogen. For example, a vaccine against Clostridial spp. is likely to be ineffective before 6 months of age, while a vaccine against Salmonella spp. may cause a beneficial response at 2 weeks of age. In another example, Dr. Chase notes that bovine viral diarrhea virus (BVDV) vaccination before 2 months of age and again at 4 to 9 months of age was not effective in preventing infection. He suggests that an initial vaccination using modified live virus at 2 to 3 months and a second at 4 months may be the best plan for BVDV.
In contrast to calves that received adequate colostrum, calves that did not receive adequate colostrum and have low total blood protein levels may benefit from vaccinations at earlier ages. However, there are no specific guidelines for early vaccination in this circumstance, and concerns regarding long-term suppression of the immune system still apply.
Always consult with your veterinarian and nutritionist for specific recommendations for your operation. To learn more about pneumonia, colostrum management and related target goals for calves up to 6 months of age, click here to review DCHA Gold Standards I.
Source: Dairy Calf & Heifer Association