Should you ask for extra vaccines during rearing?

Pullet rearers usually offer a comprehensive vaccination package, but their customers are increasingly asking for extra vaccines to be administered.

Many are requesting add-ons to combat specific ailments found on their farms, with some even paying for autogenous vaccines tailored to individual disease strains. But how valuable are these extra vaccines, and what impact do they have on the birds?

Steve Carlyle of Country Fresh Pullets, which rears more than 7m pullets a year, says he is concerned by the number of extra vaccines that producers are asking for. “In the 16 weeks it takes to rear a bird we give 18 live vaccines, plus a dead vaccination on loading. Every vaccine challenges the immune system, so it is a struggle to maintain body weight growth.”

Although all birds receive the standard vaccine programme (see box), there are 68 variations, with free-range producers, in particular, demanding extra vaccines. “As free-range sites get older there is a likelihood that the flocks will face more disease challenges, so there is a greater need for more vaccines.” The most common add-ons are Erysipelas, Pasturella, Mycoplasma Gallisepticum, and E.coli.

“Increasingly, producers are asking for autogenous vaccines to suit their farm,” says Mr Carlyle. This requires significantly more work by the rearer, as the vaccines have to be tested on the pullets for adverse reactions before widespread use.

“It is not an easy job, as some of the extra vaccines have to go into the breast as well as the leg. It challenges the bird: it is a shock being picked up and handled as a young bird, and you can lose four days’ growth just by giving one injection.”

With about 10% of customers requesting autogenous vaccines, and 25% asking for other add-ons, vaccinations are becoming a significant part of the rearing process, he adds. But it doesn’t stop there. A significant number of free-range producers now vaccinate their hens in-lay, to combat infectious bronchitis (IB) and IB variants – and that number is increasing.

Vet Paul McMullin, from Poultry Health Services, says producers who use live IB vaccines in lay tend to have multi-age sites or are in areas of high poultry density. Some will vaccinate every six to 12 weeks, to provide ongoing boosters against the disease, where it has previously been identified as a risk.

However, not all vaccines are approved for use during lay. “There can be drawbacks to vaccination as it activates the bird’s immune system. But the better the vaccinations in rear, the less likelihood of subsequent reactions.”

Egg producers should work closely with their vets to create a flock health plan and identify if any extra vaccines are needed, Mr McMullin adds. “Vaccination programmes need to take into account the expected disease challenges at each step in the chain – and the best results are achieved by teamwork. I encourage everybody in the chain to communicate well, without being unnecessarily prescriptive, particularly in the timing of live vaccines.”

Ideally, producers should also check the bird’s response to vaccines through blood testing at about 22 weeks of age, says Richard Turner, poultry vet at St David’s Poultry Team, Exeter. “Production is the best test of a vaccination programme and if production is satisfactory don’t change a thing.”

However, some vaccines given in rear may not last through the hen’s entire laying cycle, with IB proving particularly difficult to protect against. “A lot of IB blood tests are not specific enough to identify individual IB variants and there’s a good chance there is a mixture of variants present. During rear ensure you’re covering as many of the options as you can – producers can then give a booster on arrival at the farm and again every 8-10 weeks thereafter with their vets agreement.”

However, producers should stick to the same IB vaccine each time, unless it fails, as changing the vaccine type poses a greater challenge to the bird. “If you spray at peak production you might get an egg drop.”

Vaccine application poses another difficulty. Many IB vaccines are administered as a spray, so the vapour is inhaled by the birds. But with a multi-tier system or large house it can be hard to know if you have vaccinated every bird, so it may be better to give the vaccine in drinking water instead.

If spraying birds it is important to use clean water as there can be bacterial contamination, which can cause disease, as the respiratory tract is being challenged by the IB vaccine and is more susceptible to other infection threats.

Giving Mycoplasma Gallisepticum, IB and TRT (Avian rhinotracheitis) vaccines too close to each other during rear can create similar problems, adds Mr Turner. “We need to rationalise some of the vaccine programmes; it’s easy to keep adding a vaccine in but difficult to take one out, so the programmes are getting crowded.

“Perhaps more vaccines should be given in lay and we could use combined vaccines and autogenous multivalent vaccines instead of individual vaccinations.”

Many vaccines are not licensed to be given at the same time as other vaccines – and some require a two-week break between any vaccination. As more vaccines are introduced, the more they are being used outside manufacturers’ guidelines, which could render the rearer liable should a vaccine fail to work.

“It always comes back to the rearer. If the birds are lame from injections, losing weight, or not producing as well as they should be, the rearer gets the blame.

“You have to accept that there can be more disease in a free-range situation, particularly in relation to Pasturella and Erysipelas,” says Mr Turner.

“If you have a problem on farm there is some sense in giving a vaccine during rear. But there is no longer a licensed combined Pasturella and Erysipelas vaccine, so they have to be given separately or as an autogenous multivalent vaccine, which is made from the strains of bacteria found on the laying farm. This needs planning and is not available off-the-shelf to the rearer.

“That is the route I would like to follow. If you can combine three vaccines into one injection it means fewer injections in to the bird.” Most injections are given into the hen’s legs, which can result in lameness; the birds then don’t eat properly and can suffer from large post-peak dips in production. Although equipment is becoming available for injections into the breast, this is slower and more costly, he adds.

Every unit is different and requires an individual approach to disease prevention. Free-range producers should develop a health plan in conjunction with their vet and be aware of any pitfalls before committing to extra – but perhaps necessary – vaccine programmes.