Pre-housing checks and timely vaccination can pay dividends when it comes to preventing respiratory disease in young stock of all ages. We take a closer look at the key areas of preparation requiring careful planning.
TEXT RACHAEL PORTER
Pre-weaning disease prevention, particularly respiratory issues, is very much on producers’ radars, but what about older heifers returning to housing, after summer grazing, this autumn?
“This is a group that can be overlooked, but it’s important not to lose focus – particularly when it comes to respiratory disease – it’s important to protect heifer health and growth rates, and the investment made in these replacements,” says Boehringer Ingelheim Animal Health’s vet Sioned Timothy.
A check list as young stock move back into housing is highly recommended, focusing on the heifers themselves, management practices, and housing. Keeping ahead of the game, and identifying and preventing potential health issues – such as respiratory disease – is typically cost-effective, and of course good husbandry practice.
“Problem areas, which require careful consideration on many units, include reducing stress and ensuring appropriate housing conditions,” says Ms Timothy. “It’s important to recognise that housing heifers puts them under pressure. Steps should be taken and protocols in place to minimise this. Young stock should, ideally, remain in the same social group, if facilities can allow this. It’s all about keeping stress to a minimum, to ensure energy isn’t diverted away from growth and towards fending off disease challenges. Stress can suppress the heifer’s immune function and can also disrupt feed intakes.”
Reduce stress
Potential parasite infestations – lungworm, gut worms and liver fluke – should be on the check list and dealt with prior to housing. Again this helps to reduce stress on young stock at the point of housing, as they face new environmental and nutritional challenges
“It’s about stacking everything in favour of the heifer before it’s time to move her. Get her fit and tackle parasites and any other potential stressors before you subject her to the challenge of being housed,” says Ms Timothy. She adds that if ‘done right’ – and with planning and care – growth setbacks or health issues should be minimised when heifers are housed. “So maximise the heifers’ chances of a successful transition to housing by mitigating all risks in the run-up to housing – and make sure housing also meets industry guidelines and standards.”
When it comes to respiratory disease, this means appropriate space and good ventilation. Ms Timothy notes that there are published guidelines on space allowance for different housing systems, with loose housing the most common approach (see Table 1). “Remember that young stock will grow over the housing period and check that stocking density will remain appropriate for the entire period to avoid an increased risk of respiratory disease,” says Ms Timothy.
A maximum group size of 12 is advocated for older calves (more than two months of age), because this makes it easier to identify sick calves. No more than 30 calves should share the same air space and, ideally, they should not share space with older cattle, although this is not always possible.
Protect investment
“It’s important for producers to protect the investment they’ve already made in heifer rearing and to prevent young stock from falling at the housing hurdle and missing the critical 24-month calving target,” says Ms Timothy. “Heifers need careful management – of both health and nutrition – throughout that two-year rearing period. Producers can’t afford to sit back and assume young heifers will just look after themselves.”
With this in mind, she urges producers to review respiratory disease control for calves on farm, and to consider the vaccine status of older heifers, just prior to housing. “This can also help to reduce the pathogen challenge faced by younger calves, particularly if they’re housed in the same shed or air space,” says Ms Timothy. “If you’ve vaccinated young calves on your unit to protect them from pneumonia then administering a booster prior to housing will ensure they have high immunity to key respiratory pathogens”
If young stock have not been previously vaccinated then consider this ahead of housing. It’s certainly a conversation to have with your vet. There are different approaches, it’s a case of working out which is most appropriate. Where an injectable respiratory vaccine is used, ensure that animals have received both doses of the primary course ahead of housing so that they are suitably protected once inside.
Ms Timothy suggests administering a vaccine to protect against the key respiratory viruses RSV and PI3, and the bacterium Mannheimia haemolytica, during a quieter period in later summer can be a practical approach. “Injectable vaccines will typically offer heifers protection for six months after the primary course is administered. So, a late-summer dose will offer protection during the transition period and well into winter housing.”
Intranasal vaccines, containing the viruses RSV and PI3, are an alternative option if there is less time available ahead of housing to allow immunity to develop. A single dose of intranasal vaccine will rapidly stimulate local immunity in the respiratory tract, with protection persisting for three months.
“Make it part of your heifer management plan and ensure the timing of vaccination is correct.”
Just like younger calves – both pre and post weaning – older heifers need clean and dry bedding, and good ventilation. “Draughts are not such an issue for older calves, but they still need plenty of space and fresh air to keep respiratory disease at bay. It really is important to avoid overcrowding. Split larger groups up when they come in from grazing, if necessary, but avoid mixing to prevent creating social stress.”
Good ventilation
A constant supply of fresh air is essential. Good ventilation removes stale, damp air, which helps ensure viruses and bacteria can only survive for short periods outside the animal. UK wind speed is, typically, above one metre per second for more than 95% of the time. This means, for most of the time, there is sufficient generating force to provide the required air changes within a correctly designed building by natural ventilation alone.
She adds that hygiene is also still important. Water trough cleanliness can be overlooked, which can result in them becoming a potential reservoir of infection. So keep them clean and make sure they’re not leaking or overflowing, to avoid wet bedding. This can create humidity, and wet bedding is the perfect breeding ground for pathogens.”
There should also be adequate trough space for feed and water to, again, prevent stress and allow young stock to maximise dry matter intakes. Cattle are herd animals and are sociable by nature. They like to behave as a group. There should be space for at least 10% of the group to drink at any one time. The water trough should be set at the correct height for heifers. “This can be a practical problem with rapidly growing animals.
“So it’s very much about planning and preparing in advance,” Ms Timothy adds. “Avoid a housing ‘rush’ and go through the checklist early. We want robust heifers at housing – with plenty of resilience. And housing that is fit for purpose and can support heifer growth and health throughout the winter period.”