Tackling the economic impacts of calf disease

Calf health is typically a critical factor in efficiency of today’s farming businesses and there is good awareness of the need to get calves off to a healthy and productive start. In financial terms, calf pneumonia or BRD (bovine respiratory disease) is one of the most impactful diseases, estimated to cost the UK cattle industry up to £80 million a year¹.

This is considerable and the individual costs for each farm will vary, but high or low, cannot go ignored.

The figure may sound high, but considering the average cost of rearing a dairy heifer is £1,819² and that she doesn’t begin to pay back these costs until she starts producing milk, any delay in this due to disease is costly.

The aim is to have heifers calve down at 24 months, which impacts on her profitability and lifetime yield. Anything which extends her age of first calving will increase rearing costs by an average of £2.87 per day³. Infectious diseases including neonatal scour and calf pneumonia heavily influence this.

A recent UK study revealed that on average cows take 1.5 lactations to pay back their rearing costs, but on 10% of farms cows don’t break even until the third lactation or later. This is a concern since, in the UK, nearly 15% of live born heifers fail to reach their first lactation³ and the average age of exit is 3.6 lactations⁴.

To consistently achieve the growth rates required for 24-month age at first calving requires appropriate nutrition and effective health management. The two main diseases affecting young calves are BRD and scour, with BRD having a huge impact on growth.

Prevention is always better than cure and developing an integrated control plan with an appropriate vaccination programme is generally a key component of this plan.

What are the objectives of a vaccination programme?

Objectives:

• Pathogen-specific immunity
• Effective protection against key pathogens
• Rapid onset of immunity
• Long duration of immunity
• No immunity gap.

Challenges:

• The calf’s immune system is still maturing
• Effect of maternally derived antibody
• Impact of external stress factors.

The immunity gap

A calf’s susceptibility to pneumonia and other infectious diseases, is influenced by the quantity and quality of colostrum she receives in the first few hours of life. It is critical that a calf absorbs enough maternally derived antibody (MDA) at this time.

Colostrum provides immunoglobulins, immune cells and other protective substances that protect the calf via passive immunity. As the calf grows older, levels of MDA decline and its own immune system begins to produce antibodies in response to pathogen exposure and other stimuli, such as vaccination.

During this transition period, MDA may drop below a protective level before the calf’s own immune system is up and running. This ‘immunity gap’ can leave the calf at higher risk of disease and may coincide with stressful events such as weaning, disbudding and castration that can also reduce resilience to disease.

Vaccination: Injectable vs intranasal

When MDA to the viral or bacterial antigens contained in a vaccine are present in sufficient quantities, it can alter the response to a vaccine administered at this time, reducing protection against disease. The impact is greatest when injectable vaccines are used so, where MDA is likely to be an issue, intranasal vaccines can be a good option.

Because intranasal vaccines interact with the calf’s immune system in a different way, the interference exerted by maternal antibodies is less of a risk⁵. Intranasal vaccination induces more rapid immunity than injectable vaccines because the immune response is initiated at the site of infection, rather than within more distant lymph nodes. In practical terms, this means the calf is protected shortly after a single dose of intranasal vaccine.

Live intranasal vaccines can provide an effective way of enhancing protection against pneumonia during the first few months of life, and of bridging the immunity gap that can occur during this period.

BRSV and PI3

Many pathogens can cause calf pneumonia, but it is recognised that viral respiratory pathogens are typically the primary invaders, causing damage to the respiratory tract that allows secondary bacterial infections to gain a foothold⁶. Bovine respiratory syncytial virus (BRSV) and parainfluenza 3 (PI3) are the most significant respiratory viruses of cattle and are endemic on most farms⁷.

Where protection against these two viruses is required early in life, Bovalto Respi Intranasal can be used from 10 days of age. A single dose provides protection for 12 weeks, with onset of immunity from 10 days after vaccination.

Using Bovalto Intranasal as the first step in a vaccine programme and, followed by a full primary course of Bovalto Respi 3 or Bovalto Respi 4, will give rapid onset of immunity, followed by longer lasting protection. A booster at six months or ahead of specific risk periods such as housing, can further prolong immunity.

Bovalto Respi 3 and 4 provide six months protection from three weeks after the initial course of two injections. In addition to providing protection against PI3 and RSV, both also protect against Mannheimia haemolytica. Bovalto Respi 4 also protects against the respiratory effects of BVD, which may be of value in some high-risk settings.

Taking steps to reduce the impact of BRD on replacement heifers early in life can have a significant effect on their lifetime performance. Working with your vet to assess farm level risk, optimise calf management, and develop an appropriate vaccination strategy can help to enhance health and productivity in both the short and longer term.

Find out more about calf health here.

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References

1. NADIS (2007). Health Bulletin: Respiratory Disease in Cattle. UK, NADIS, pp 1-3.
2. Boulton et al. (2017) Animal 11: 1372-1380
3. Brickell and Wathes (2011) Journal of Dairy Science 94; 1831–1838
4. Hanks & Kossaibati (2020) Key Performance Indicators for the UK national dairy herd. University of Reading.
5. Woolums et al. (2004)J.Vet.Res. 65: 363-372
6. Griffin et al. (2010) Veterinary Clinics of North American Food Animal Practice 26:381-994.
7. Caldow (2011) UK Livestock 16:29-40.