In 1796, Edward Genner used cowpox virus on a 13-year-old boy to give immunity against the smallpox virus. So began vaccination. The name is derived from the Latin word “vaccinia”, which means cowpox. Vaccines have moved on considerably and now are the mainstay of health programmes in both humans and animals.

So, how does a vaccine actually work? It stimulates immunity when given – this is like a memory of the disease (often a dead strain or a low level of the live disease). Then when the animal is exposed to that disease its immune system’s memory kicks in to provide a greater and more effective response.

Why is this important?

Everyone knows vaccines are expensive and to get the best results we must know some of the most important principles. If you are using a dead vaccine that requires two injections, for example, it is not until the second shot is given that you will see the proper immune response. This means the timing of when you give it is very important. If we know weaning is the key risk time, it is really important that we have that immune memory primed well in advance of the risk.

Next thing is each vaccine will evoke a pretty specific memory or immune response against the agents in it. So, as we discussed last week, it is important to diagnose the viruses or bacteria that might be active in your herd.

It is also important to remember vaccines are sensitive and storage is really important. Most require refrigeration and once opened may have a specific shelf live. I have seen them being administered in the wrong way many times also. This is why it is key to talk to your own vet about the right advice, the right product, right dose/storage and particularly timing.

In no way are vaccines the answer to all your pneumonia problems. They are a significant help to prevention when used correctly. With tightening legislation looming around oral antibiotics use, vaccines will increasingly be used on farms.

Something that confuses people is the difference between live and dead vaccines. A lot of IBR vaccines are live, meaning they are quick-acting, often only require one shot and can be given in the middle of a problem. Dead vaccines often require two shots and it is not until the second shot is given that the immunity reaches the level to be of benefit.

For a vaccine to get its best results, it requires a healthy immune system to respond to it. Time spent planning a vaccination programme is time well spent on any farm. Some farms will not vaccinate and get on fine – you will often find these are closed herds with excellent management.

If you are using lots of antibiotics every year, then certainly part of a long-term strategy should be vaccination.

Few factors in controlling pneumonia are as important as getting ventilation right. In simple terms, it is about getting plenty of fresh air into sheds, nature’s cheapest and most effective disinfectant.

I always talk about ventilation in two distinct categories, first young calves and secondly anything weaned with a functioning rumen. They are different because the rumen is a fermentation bath that not only drives the nutritional performance, it also generates heat. This means the housing and ventilation requirements for older stock are very different to those of younger calves.

A young calf is most comfortable at 10-20°C, while an adult weaned animal is comfortable at 0-15°C. A baby calf at two weeks and a finishing bull are very different animals. So for the purposes of this we will focus on the weaned animal generating this heat.

This animal generates heat which rises and, by escaping out an outlet, will draw fresh air into an inlet. This is known as the stack effect. In our videos we explain this in more detail and also go through an assessment of a shed.

Housing is a huge change in the environment of the animal, from often green pastures to winter confinement. The comfort of that house will have a huge impact on how stressed the animal is and then how susceptible they are to circulating viruses and bacteria.

From a pneumonia perspective, this becomes very important when we talk about fresh air. Let’s check the shed under these general principles:

1 Positioning: if we are relying on natural ventilation, the long axis of the shed should be facing the prevailing wind. This allows good airflow.

2 Outlet: this should be 1m2 per 500kg animal.

3 Inlet: ideally twice the outlet on both sides, 2m2 squared per animal

4 Dry: reducing moisture reduces humidity and reduces the conditions bacteria and viruses survive well in.

5 Stocking density: this plays a key role as well. The more animals, the more heat and humidity. It also means closer contact, which means it is more likely to spread.

6 No draughts: we want fresh air but excessive air speeds aren’t good.

What is mechanical ventilation?

Due to the fact that fresh air is so important, in some cases we will take control of airflow ourselves. This is by using fans or wind tubes to blow air through sheds to help with circulation of fresh air.

I have certainly upped my game since I first started looking at sheds. I had to because I realised this was one key area to address if I was going to have an effect on pneumonia problems.

But it is still simple principles. In the video I show my simple checklist.

We can’t all build new sheds, but we can make alterations to existing structures to make them better.

One thing that plays a big role is stocking density. You might say: “I don’t have any space.” This might be the case, but the value in reducing numbers in pens can’t be disputed. Often there are alternatives on farm such as a machine shed that might just take pressure off?

Go online to see how we use our check list to look at sheds.

This is a simple way of assessing airflow in any shed. Of course, the weather on the day will affect results, but it still can provide valuable information.

So, when letting off smoke bombs there are three things that can happen:

1. The smoke is blown away very quickly by excessively drafty sheds (not ideal).

2. It lingers for minutes, meaning poor airflow – the worst-case scenario. If you are having pneumonia issues at housing, it really is worth assessing sheds properly.

3. Ideally it circulates up and out the outlets, being replaced by valuable fresh air.

We can use smoke bombs also to assess airflow between sheds. This can be useful when looking at air movement between groups of cattle. Remember, young weanlings sharing airspace with older animals shedding disease can be an increased risk as well.