Are your beef cattle autumn ready?

Beef cattle are subjected to many stressors during the autumn period – weaning, sales and housing can result in a stress response that negatively impacts cattle’s immunity. Cattle are then susceptible to developing diseases, namely BRD, the umbrella term for diseases that affect the respiratory system of cattle, one of which is pneumonia.
With the implementation of EU Regulation 2019/6, disease-control strategies are more important than ever. This legislation states that antimicrobials should not be used routinely, nor should they be administered to compensate for poor animal husbandry and inadequate hygiene practices. With antibiotic use under scrutiny, farmers are advised to respond and adapt their management practises accordingly.

Bovine respiratory disease

BRD is a complex, multifactorial disease which involves interactions between the animal, infectious agents and the environment.

BRD is associated with significant economic implications worldwide. These are not only restricted to treatment costs and deaths but decreased daily live weight gain and feed conversion efficiency. In one study, beef cattle took 59 days longer to finish when they were showing obvious clinical signs of pneumonia. In the same study, it was found that cattle that did not appear sick but were simply in the same pen as the cattle showing signs of pneumonia took on average 33 days longer to finish.
BRD is the most frequently diagnosed cause of death in cattle greater than one month of age in Ireland. For cattle from six months to one year of age, BRD accounted for 41 per cent of post-mortem diagnosis cases at Irish regional veterinary laboratories in 2022, a higher figure for BRD deaths than seen in recent years. Dictyocaulus viviparus (lungworm), Mannheimia haemolytica, Pasteurella multocida, Mycoplasma bovis, Histophilus somni and respiratory syncytial virus (RSV) were the most common pathogens detected on post-mortem associated with respiratory disease in 2022.
Viruses and bacteria often affect cattle at the same time. A viral infection first compromises lung defence mechanisms. Cattle are then at risk of developing bacterial infections of the lower respiratory tract. Commensals (bacteria that live in the respiratory tract of healthy animals) are often associated with respiratory diseases. The most common bacterial pathogen implicated in BRD in 2022 was a commensal called M. haemolytica (17 per cent).

Sub-clinical BRD

Cattle can often suffer from sub-clinical BRD, where the usual clinical signs of BRD, such as panting and a runny nose, are not present and the animal appears healthy. It is reported that the prevalence of sub-clinical cases, according to one study, can range from 23-67 per cent. These results are further supported by another study where 64 per cent of animals were found to have at least one lung lesion (an abnormal area of lung, suggesting recent or previous BRD) present at slaughter. BRD can be present even where the farmer does not suspect it. Detecting clinical respiratory signs simply by observing animals has its limitations when it comes to sub-clinical cases. Identifying animals in the early stage of disease and treating appropriately under veterinary supervision is essential for best outcomes.

Disease-prevention strategies

Animal husbandry practices
It is vital to engage with your veterinary practitioner in advance of the risk periods this autumn and get advice on a plan of action. The following recommendations will help maximise calves’ immunity and minimise infectious pressure at weaning:

• Avoid abrupt weaning.
• Avoid additional stressors such as dehorning, dosing or castration at weaning.
• Introduce concentrates to calves at least four weeks prior to weaning, gradually increasing to a minimum allowance of one kilogram per day at weaning.
• Provide fence-line contact with cows or other methods of gradual weaning such as drafting individual cows from a group or creep grazing calves prior to weaning.
• Implement a strategic worming programme under veterinary guidance during the grazing season (particularly for lungworm), and carry out a vaccination programme for respiratory disease well in advance of weaning.

Like weaning, both housing and sales pose as major stressors for cattle. The following recommendations will optimise weanlings’ immunity and/or decrease infectious pressure:

• Avoid overcrowding.
• Avoid mixing different age groups in the same air-space.
• Ensure adequate feed space allowance.
• Delay housing for a period post-weaning, quarantine newly purchased animals for four weeks ideally.
• Should fluke dosing be required, work with your vet to develop a targeted fluke programme. This could involve dung sampling to determine fluke egg counts.
• Vaccinate all animals in a group pre-housing and newly purchased animals when settled.
• Sell at least two weeks post weaning.
• Provide adequate lighting (minimum 100 lux) in sheds so sick animals can be detected early while also helping animals to find feed/water in their new environment.
• Isolate sick animals from healthy animals.

Vaccination

Good husbandry practices outlined above in conjunction with a correctly timed vaccination programme is key to reduce incidence and severity of respiratory disease. Vaccination programmes will vary depending on the product used.

For example, Bovilis Bovipast RSP protects against both viral and bacterial agents, namely RSV, PI3 and M. haemolytica. This vaccine provides the broadest protection on the market against M. haemolytica, being the only cattle vaccine licensed to protect against both serotypes A1 and A6. Serotype A6 of M. haemolytica was found to account for 63 per cent of M. haemolytica infections in young beef animals. The primary course for this vaccine involves two injections administered under the skin four weeks apart. The second injection should be given two weeks before a known risk period such as weaning, housing or sale. For bought-in weanlings, it can be administered any time after arrival, ideally allowing a short rest period before handling (e.g. overnight) and followed up with a second dose four weeks later.

Another vaccine option to consider when there is only a short time-frame available before the known risk period is Bovilis INtranasal RSP Live. This live vaccine provides fast protection against RSV and PI3, with an onset of immunity of seven days.This is a single dose and should be administered up the nose at least one week before the risk period.

Infectious bovine rhinotracheitis

Infectious bovine rhinotracheitis (IBR) is a viral cause of BRD and another common pathogen worth controlling. Bovilis IBR Marker Live is a single dose vaccine against IBR. The vaccine can be administered either up the nose or into the muscle in cattle over three months of age. It should be given two weeks before a known risk period and provides the fastest onset of immunity of four days post intranasal vaccination. This initial vaccination should be followed by a booster six months later with subsequent re-vaccination six to 12 months later. 

Conclusion

Adopting good farm-management practices, and a vaccination programme with an emphasis on disease control, will not only positively impact productivity and profitability but will help reduce antibiotic use on farm.