Note: This is the second in a two-part series on immunology and the importance of building immunity in the calf. To read the first-part, click here.
Immunology: A practical approach for weaning
The immune system plays a crucial role in mitigating stress-associated disease risk in calves. Stressed calves have a weaker immune system and lower response rate to vaccination, traditionally making treatment difficult.
Early immunization, however, allows immunity to be established prior to the challenges that occur during weaning. The opportunity to prime the immune system through vaccination at a young age, by generating a mucosal immune response, helps set up the animal for a more effective cell-mediated immune (CMI) response, and subsequently more robust long-term immunity.
Building the immune reserve
Vaccinations play a pivotal part in establishing and building immunity in calves and serve as an important pre-conditioning insurance plan. How soon after birth can a calf be effectively immunized? Or, in other words, how soon can we start priming the immune system?
Until recently, there was uncertainty regarding the timing of calf vaccination. This was due to long-held beliefs that the newborn calf's immune system would not be sufficiently developed to respond appropriately to vaccination and that interference by maternal antibodies would adversely impact the effectiveness of any vaccine. Those beliefs are fading quickly thanks to new research demonstrating calves can respond to vaccination even before birth. As noted in the last issue, we now understand calves have a fully functional immune system at approximately 150 to 170 days of gestation. This understanding has led to significant improvements in our approach to vaccinating young calves; and subsequently, improving critical immune function.
Alternative routes of vaccine administration
Recent developments in vaccine administration, like intranasal vaccination, now offer producers better ways to more quickly address respiratory disease in high-stress animals while priming the immune system.
Intranasal administration means the vaccine antigens are delivered directly to mucosal surfaces in the nose – the major sites of immune response in cattle – stimulating a faster response, as well as more rapid protection. It also has been shown that intranasal immunization can provide system-wide immunologic memory to future infection; hence, priming the immune system.
Because intranasal vaccine antigens are delivered directly to the nasal mucosa, where maternal interference is less likely, most young animals respond to vaccination and develop active immunity. In addition, application of intranasal vaccine administration may help close the window of vulnerability during which maternal antibodies' waning powers still repel vaccines but leave animals vulnerable to diseases. This is depicted in the figure below:
|Veterinary Clinics Food Animal 24 (2008). Neonatal Immune Development in the Calf and its Impact on Vaccine Response Chase, Hurley, Reber
Intranasal administration is extremely Beef Quality Assurance friendly. Because there is no injection site, carcass quality is not compromised by vaccination. Intranasal vaccination also is the least stressful form of vaccine administration.
Tying it all together
A more thorough understanding of the bovine immune system has led to several distinct advantages in controlling and preventing infectious disease, as well as developing more effective vaccines, including:
- Vaccine applications for high-risk cattle, such as weaned calves
- Vaccine applications for newborn calves
- The ability to overcome maternal antibody interference
- The ability to create early immune memory, thus priming the immune system for lifelong health
Talk with your veterinarian to determine if intranasal vaccination is right for your operation.
Scott Nordstrom, DVM, is manager veterinary technical services at Intervet/Schering-Plough Animal Health. For more information contact Scott.Nordstrom@sp.intervet.com.