Do Better Vaccine Practices Make Healthier Calves?

Background

Vaccines and a good vaccine protocol is a powerful tool to prime and boost the immune system to improve cattle’s ability to fight common diseases. Keeping vaccines at the appropriate temperature during storage, preparation and use and using the correct syringes and needles positively impact the effectiveness of the vaccine. This is especially true for preparing modified live vaccines (MLV) which rapidly lose effectiveness if exposed to temperatures above 8°C or below 0°C. Best practices are described on product labels and often explained by veterinarians but producers don’t always follow these instructions to the letter, and that may cost them more than they realize. It is unclear how much money is being left on the table from preventable diseases occurring despite being vaccinated because of poor vaccine practice on-farm.

Objectives

•  Evaluate the effectiveness of good compared to poor vaccine practices on priming immune response after vaccination

What they Did

Two weeks before weaning, 136 calves at AAFC Lacombe were vaccinated using a modified live vaccine that is mixed either 6 hours or 1 hour before use, and stored either in a cooler or outside (at room temperature). Additionally, a control group (n=14) with no booster vaccination was included to capture the immune activation due to natural exposure to viral pathogens after weaning. Blood samples were collected from calves before vaccination and four weeks after the study to measure immune responses against five different viral pathogens. The body weight of calves was collected at the enrollment, post-vaccination, and pre-slaughter.

Immune responses to viral pathogens were measured using two different approaches; 1) antibody units against parainfluenza virus-3 (PI3), bovine respiratory syncytial virus (BRSV), and bovine herpes (IBR) and 2) viral neutralizing titers against bovine viral diarrhea virus (BVDV 1 and 2). Antibody titers against PI3, BRSV, and IBR, and viral VN titers against BVDV 1 and 2 were elevated post-vaccination compared to pre-vaccination, regardless of the vaccine handling method.

What They Learned

The impact of good vaccine practices on immune priming (a positive antibody or viral neutralization (VN) titer at four weeks after boosting) was dependent on the pathogen. In the control group (no boosting), 93% of the calves were not primed against Bovine Viral Diarrhea Virus (BVDV) 1 and 2. Additionally, 50% and 29% of control calves were not primed against infectious bovine rhinotracheitis (IBR) and bovine respiratory syncytial virus (BRSV), respectively. However, all calves in the control group were primed against parainfluenza virus 3 (PI3) after weaning. This means the control group were naturally exposed to PI3, BRSV, and IBR, and the post-vaccination immune responses was likely due to a combination of infection and vaccination for these specific pathogens. However, boosting at weaning is vital to enhance the BVDV neutralization titers of weaned beef calves. Keeping a mixed MLV longer (6 hours) decreased the number of animals that generated a positive immune response against BVDV 1 by 89% compared to the short mixing time (1 hour). Storing a mixed vaccine at room temperature decreased the number of animals that generate a positive immune response against BVDV2 by 65% compared to storing it in a cooler. When comparing among four treatments, long mixing time and stored at room temperature decreased the number of immune-primed calves against BVDV1 and BVDV2 by 89% and 86%, respectively compared to short mixing time and stored in a cooler (SC).

What It means

Booster vaccination before weaning is vital for inducing antibody responses against viral pathogens in weaned beef calves, who were primed using parenteral modified live vaccines (MLVs) at spring turnout. The impact of good vaccine practices on priming immunity against viral pathogens varied depending on the pathogen. Use of good vaccine practices including short mixing time and storing mixed vaccines in a cooler, increased the number of immune-primed calves against BVDV. Essentially, good vaccine practices are vital to generate protective immune responses and increase herd immunity.