Deciding to vaccinate
To make the decision whether to vaccinate or not, you need to consider the:
- cost and impact of disease, including welfare implications
- likelihood of the disease occurring
- cost of vaccine
- efficacy of the vaccine.
- are not usually 100% protective, and even with vaccination some animals may succumb to disease. Cattle in poor body condition or under severe stress may not respond as well to vaccines as healthy cattle.
- may not necessarily stop an animal being infected or transmitting the disease. In most cases they stop the outcome of the disease, and they may or may not stop infection.
- may mask a disease being present.
These aren’t reasons not to use a vaccine, but they must be understood to get the best value from a vaccine.
Let’s look at two examples
1. Blackleg in finishing animals
A producer is concerned about the potential to lose steers from blackleg. Blackleg usually occurs in well grown animals if they get a bump in the yards or similar injury, which can happen when handling finished animals coming up to sale. The producer vaccinates the calves at marking with 5-in-1 and is wondering if this is sufficient.
To get effective protection, the producer needs to give a second booster dose, and this needs to be done at least 7-10 days before the steers are exposed to the risk of blackleg. A single vaccination at marking will only provide a small level of protection 2-3 weeks post marking.
With 300 calves and a 98% protection from vaccination, it will cost $150 ($0.50) for the extra vaccination. If the producer saves an animal every 10 years it will have paid for itself (assuming finished cattle are valued at $1,500).
2. Pinkeye in cattle
A producer is concerned about pinkeye at weaning because they yard wean their cattle in March and it’s sometimes dusty. The producer gives a 7-in-1 at marking and again at weaning, and is wondering if it is okay to give a pinkeye vaccination at weaning as well, and if it is worth doing.
Last year, the producer had at least six steers out of 150 (4%) rejected by the feedlot from old pinkeye damage, and both the steers and the heifers were affected. The rejected steers were sold for 30¢/kg less (a loss of $120/head).
Piliguard® vaccine is a single dose vaccine but takes 3-6 weeks until vaccinated cattle are immune. In this case, if the main challenge is occurring at weaning, then calves would need to be vaccinated at least three weeks prior to this.
In fact, it is worth vaccinating at marking to save extra handling and provide protection when flies are around in late spring/summer as well. It is fine to give animals both 7-in-1 and pinkeye vaccinations at the same time (they are given separately, so each calf would get two vaccinations).
The single dose will cost approximately $5/head (i.e. $1,500 for 300 calves). The loss of the steers was $720, and it is reasonable to assume that there were similar ‘losses’ in the heifers, either in terms of marketing or bodyweight and fertility effects. Company data suggests the vaccine is about 85% protective, so there would still be possibly one or two animals affected even with vaccination.
The net outcome of vaccination in this scenario is about break-even (a loss of $276 from a sale value of $480,000; break-even at 5% prevalence). The break-even point if each case of pinkeye cost $80/head would be a 7-8% prevalence, and if each case resulted in a $150 loss the break-even would be about 4%.
Of course, the fact that pinkeye is difficult to treat, and handling animals can spread the disease to other animals, as well as the welfare aspects for the animals affected, means that even at break-even (or below), vaccination is likely the preferred strategy.
These scenarios emphasise the importance of assessing the likelihood and level of disease in the absence of vaccination, something which is always easy in hindsight but difficult in reality. Where there is any risk of disease, and a vaccine is available, vaccination to prevent or minimise disease will be a cheap and almost always worthwhile investment.