Many cattle producers stopped boostering vaccines at the recommended four to six weeks apart as situations on farms changed and herds got larger.
They left the initial vaccination to before weaning and then boostered it at weaning. Older calves in the spring were given blackleg because we knew for sure that colostral immunity would wear off, but the other vaccines were dropped.
Summer pneumonias increased in incidence, often caused by respiratory viruses such as bovine respiratory syncytial virus and shipping fever bacteria such as pasteurella and mannheimia.
Producers started vaccinating much earlier to try and avoid these summer pneumonias, which occurred when calves were hard to spot and check.
Even though the second booster shot was months apart, producers noticed that morbidity and mortality seemed lower.
When immunologists checked into this, they discovered that the booster response from the second vaccination (even though months later) was very good. Over time it was found that protection was good with many months in between booster shots.
This was great because vaccinations could be better co-ordinated with other management procedures, and in most cases did not require a separate pass through the chute. Whether it was weaning, implanting or deworming, the second shot of vaccine can be given at the same time as these procedures.
There was always the worry about vaccinating calves too young because of the blocking from colostral immunity.
The calf ingests colostrum in the first few hours of life, and the immunoglobulins in the colostrum contain antibodies against the diseases that cows have been vaccinated for and to which they are naturally exposed. This blocks the humoral immune response of the calf.
However, researchers have recently discovered that calves that are vaccinated at a very young age are still protected many months out because of cell mediated immunity.
The bottom line is that very young calves can be vaccinated for the diseases that affect them.
This also ties into when it is best from a management perspective to combine this with other procedures.
Many producers are calving later, so calves are either born on grass or go to grass at a very young age. As a result, the only opportunity to administer protective vaccines is at a very young age. Otherwise, the next opportunity to process them is later in fall when they come off grass.
Calves that aren’t vaccinated at a young age can be susceptible to calfhood diseases, including blackleg organisms.
It is far better to vaccinate them when they are very young if that is the only opportunity to do so rather than waiting until fall.
Many labels don’t approve vaccines for calves younger than three months because that’s the youngest the calves were tested when the vaccines were approved.
Some companies are now testing their vaccines on calves as young as three days to a week.
Some day we may be able to vaccinate calves as young as one day old while applying ear tags and processing them with their shots at birth.
The only problem with this is if modified live vaccines are used. Producers need to use the low dose bottles and group calves together in multiples of 10 so that they can vaccinate them all within two hours of rehydrating the vaccine. Some vaccines are made in individual doses, which helps.
Vaccine manufacturers are using more intranasal technology, which is easy to administer to inquisitive young calves and less stressful because there isn’t the pain of a needle.
These products are being tested on very young calves, which is an indication of their safety.
A few intranasal vaccines are now available for IBR PI3, and one includes BRSV.
A new intranasal vaccine that has just been released and works for the bacterial causes of pneumonia Mannheimia and Pasteurella, has been tested on week old calves.
Safety work was done using both intranasal vaccines at the same time, each up one nostril. This allows producers to give protection for all the main respiratory pathogens except BVD.