Calf Pneumonia

Pneumonia in the young, pre-weaned dairy heifer calf can have a long term impact on her overall lifetime productivity. The first 8 weeks (56 days) in the life of a dairy heifer are crucial, as growth rates, at this early stage, have long term effects on the ability of that animal to produce milk in the future. This is in part due to the development of the mammary tissue in the young calf, which is highly responsive to nutrient intake1. Anything that hinders nutrition and health in the young calf can have long term detrimental effects which contribute to a loss in production and farm profitability.

Good growth rates in young calves bode well for the future as, on average, for every additional 100g of average daily weight gain during the first 2 months of life, about 225kg of additional milk in the first lactation can be expected2. Recent Irish studies3 showed pneumonia in young, pre-weaned calves can reduce first lactation yield by 4% and second lactation yield by 8%. In animals that suffer pneumonia relapses, first and second lactation yields are reduced even further, by 5% and 10% respectively. Pneumonia in young calves has been shown to reduce growth rates by 3%-9% which cannot be overcome by compensatory feeding.

When dairy heifer growth targets are missed (due to ill health etc.) they are unlikely to be on target for breeding at 15 months of age and calving at 24 months of age. Heifer calves that develop pneumonia have a delayed age at first calving and are known not to last as long in the milking herd, with reduced days in milk over their lifetime compared with calves that never suffer from pneumonia.

According to the 2014 All Island Disease Surveillance report 47% of all respiratory disease diagnoses in Irish Veterianry labs were in calves less than 10 weeks of age, which indicates that these young calves are the animals that are most susceptible to pneumonia.


  • An average cost of €53 per case at time of disease4 (Treatment costs, time etc.)
  • Increased age to first calving by 2 weeks5
  • Reduction in 1st lactation yield by 4%3
  • Reduction in 2nd lactation yield by 8%3
  • Reduction in the number of overall days in milk for individual animals by an average of 109 days6

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  • The first 8 weeks (56 days) in the life of a dairy heifer are crucial, as growth rates, at this early stage, have long term effects on the ability of that animal to produce milk in the future. 

    A 2012 study by Alex Bach demonstrated that for every 100g of increased average daily gain during the first 2 months of life, an additional 225kg of milk could be expected during the first lactation. This study was a compliation of 7 other studies which all indicated that growth rates during the first few weeks of life are critical to future milk production.

    Another 2012 study by Soberon focused on the relationship between growth rates both before and after weaning and lactation performance.

    Looking at over 1,800 first lactations this study showed a strong relationship between average daily gain (ADG) pre-weaning and milk production so that for every additional kg of ADG pre-weaning first lactation milk production is increased by 850 kg. 

    The second objective of this study was to evaluate the effects of pre-weaning nutrition on mammary gland development. The mammary gland was shown to be responsive to nutrient intake such that the parenchymal mass of calves that consumed more nutrients grew 5.6 times faster than that of control calves. This was significant because it demonstrated that mammary tissue growth can be initiated from birth and that the mammary gland is very nutrient responsive.

  • A study by Tony Andrews involved an investigation into the cost of twelve outbreaks of pneumonia (eight dairy-bred herds and four suckler herds) as they occurred on farm. The pneumonia outbreaks, on ordinary commercial farms, were followed throughout their duration and involved all calves with apparent clinical infection, and some calves without as controls. Calves were examined and weighed at weekly intervals until five weeks after the end of the outbreak. The study took place in the winters of 1997-98 and 1998-99. Most outbreaks occurred in mild moist weather with a high humidity. The ventilation was adequate on four farms, but on the other farms it was unsatisfactory. Because of the husbandry systems used and the fact that most calves were homebred, on all farms different age groups shared the same air space. While all the suckler herds were adequately fed, six of the eight herds with dairy-bred calves had inadequate diets. Looking at the overall costs, those immediately tangible to the farmer, namely veterinary and medicine costs, came to about 40% of the total costs of an outbreak. The remaining costs, which included mortality, weight loss, extra labour and other costs were higher. In all studies, weight reductions or reduced weight gains during the outbreaks were the highest cost in both dairy and suckler herds. The second highest cost was that of medicines. When mortality occurred, it became a major cost input. In the dairy herds, costs tended to increase when theoutbreak was protracted and in the suckler herds it was more dependent on the severity of the illness. In many herds the consequences of the pneumonia outbreak were still apparent after the end of the study.

  • The aim of the Van Der Fels Klerx 2002 study was to obtain expert data on the effects on productivity associated with bovine respiratory disease (BRD) in dairy heifers. Results indicated that:

    1. Mortality (rate of death) following severe pneumonia in heifers less than 3 months of age was increased by nearly 20% (range 16–24%).
    2. Body weight of heifers that had pneumonia was estimated to be reduced by 10kg (range 2–18 kg) at 3 months,  and 29 kg (range 23–36 kg) at 14 months.
    3. Pneumonia delayed age of firat calving by 2 weeks on average (range 0.1–0.9 months).
    4. BRD outbreaks in heifers >3 months were also estimated to reduce body weight at 14 months by approximately 30 kg (range 11–54 kg).
  • A study published 2011  by Stephen Morrison in Northern Ireland showed that:

    Pneumonia in pre-weaned calves

    • Reduced 1st lactation yield by 4%
    • Reduced 2nd lactation yield by 8%

    which cost GB£247 (€330) over 2 lactations

    Calves that had pneumonia relapses (multiple treatments) had

    • Reduced 1st lactation yield by 5%
    • reduced 2nd lactation yiled by 10%

    which cost GB£297 (€396) over 2 lactations

[1] Soberon 2012

[2] Bach 2012

[3] Morrison 2011

[4] Andrews 2000

[5] Van Der Fels Klerx 2002

[6] Bach 2011

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