{"id":9860,"date":"2026-05-27T15:42:47","date_gmt":"2026-05-27T14:42:47","guid":{"rendered":"https:\/\/www.cynomys.it\/?p=9860"},"modified":"2026-05-27T15:43:01","modified_gmt":"2026-05-27T14:43:01","slug":"calf-housing-air-quality-health-performance","status":"publish","type":"post","link":"https:\/\/www.cynomys.it\/en\/calf-housing-air-quality-health-performance\/","title":{"rendered":"Fresh Air in the Calf House: The First Investment for Healthier Calves"},"content":{"rendered":"\n

Guest post by Fabiana Surace, CMO and Environmental Scientist at Cynomys<\/em><\/strong><\/p>\n\n\n\n

Air quality in calf housing is often treated as a secondary concern. Colostrum, nutrition, hygiene, health protocols \u2014 everything else seems more urgent, more measurable, more immediate. Yet the most recent scientific literature tells a different story: the air calves breathe \u2014 especially at muzzle level \u2014 has a concrete impact on respiratory health, welfare, infectious pressure, and growth performance.<\/p>\n\n\n\n

It is not enough for the barn to feel well-ventilated at the operator’s head height. Calves live and rest close to the bedding, where ammonia, moisture, microbial aerosols, dust, and stale air can all accumulate. The real parameter to assess is not the comfort of the people working in the barn, but the calf’s microclimate<\/strong>: the air the animal actually breathes in its pen, hutch, or group housing.<\/p>\n\n\n\n

Why the Environment Affects Calf Health<\/h2>\n\n\n\n

Young calves have a vulnerable respiratory tract and an immune system still under development. When the environment is damp, poorly ventilated, or contaminated, the risk is not merely one of discomfort: the probability increases that infectious agents, irritants, and environmental stressors act together, amplifying each other’s effects.<\/p>\n\n\n\n

Poor air quality can contribute to four main problems.<\/p>\n\n\n\n

First: it irritates the respiratory tract.<\/strong> Ammonia, even at relatively low concentrations, is an irritant for mucous membranes and the respiratory system. Guidelines indicate that levels of 25 ppm can already increase animals’ susceptibility to respiratory disease; more recent literature suggests caution below 10 ppm.<\/p>\n\n\n\n

Second: it increases infectious pressure.<\/strong> Moisture, dirty bedding, dust, and poor ventilation promote the persistence of microorganisms and aerosols in the environment. Adequate ventilation is not a luxury \u2014 it is necessary to reduce humidity, dust, endotoxins, and airborne pathogens.<\/p>\n\n\n\n

Third: it worsens thermal comfort.<\/strong> Damp cold, draughts, and stagnant heat increase stress and can affect feed intake, growth, and general welfare.<\/p>\n\n\n\n

Fourth: it makes herd health management more difficult.<\/strong> When the environment is unfavourable, even good clinical management becomes reactive: more animals are treated, antibiotic use rises, and the ability to genuinely prevent problems diminishes.<\/p>\n\n\n\n

Ammonia: More Than an Odour, a Management Indicator<\/h2>\n\n\n\n

Ammonia is one of the most important parameters to monitor because it arises from a very concrete combination: urine, faeces, wet bedding, temperature, insufficient ventilation, and the time dirty material remains in place.<\/p>\n\n\n\n

For many years, ammonia control relied on spot measurements or subjective odour assessments. But recent studies show that this approach can seriously underestimate calves’ actual exposure.<\/p>\n\n\n\n

A Swiss study published in Animals<\/em> in 2024 monitored ammonia concentrations in veal calf housing over 14 weeks using both stationary sensors and mobile sensors attached to the animals’ heads. The results are telling: 4-hour ammonia averages were 5.9\u20139.4 ppm with fixed sensors, but rose to 11.3\u201314.7 ppm with sensors positioned near the calves’ heads. Mobile sensors also recorded higher peaks and greater fluctuations.<\/p>\n\n\n\n

The practical message is clear: a measurement taken at a fixed point in the barn may not accurately reflect what the calf is actually breathing.<\/strong> Continuous monitoring at animal level is far more informative than an occasional spot check.<\/p>\n\n\n\n

A second key study, conducted by Katharina van Leenen<\/a> and colleagues and published in Preventive Veterinary Medicine<\/em>, assessed 60 cattle farms and 428 group-housed calves. Results showed a direct link between air quality and lung health: hours with ammonia above 4 ppm were associated with a higher risk of pulmonary consolidation, and ammonia concentration was associated with a higher proportion of epithelial cells in bronchoalveolar lavage \u2014 a marker consistent with mucosal damage or irritation.<\/p>\n\n\n\n

The same study found that air velocity above 0.8 m\/s was associated with an increased risk of deeper pulmonary consolidations. This is an important finding: the solution is not simply “more airflow.”<\/strong> Ventilation must renew the environment without creating harmful draughts.<\/p>\n\n\n\n

Poor Air Quality and Antibiotic Use<\/h2>\n\n\n\n

Air quality has implications beyond the individual respiratory episode. A Swiss study from 2019, conducted across 43 veal calf farms over one year and published in Preventive Veterinary Medicine<\/em>, analysed management, barn climate, animal health, and antimicrobial use.<\/p>\n\n\n\n

The results are significant. Respiratory disease was the primary indication for antimicrobial treatment, accounting for 81.1% of all treatments. Furthermore, a peak ammonia value above 10 ppm in the calf pen was associated with a higher incidence of antimicrobial treatment.<\/p>\n\n\n\n

The authors’ conclusion is unambiguous: air quality, ventilation, and pen cleanliness must be addressed as priorities to improve calf health and<\/strong> reduce antimicrobial use.<\/p>\n\n\n\n

CO\u2082, Temperature, and Humidity: Reading the Microclimate as a System<\/h2>\n\n\n\n

CO\u2082 is not the primary respiratory irritant in calf housing, but it is a reliable indicator of insufficient ventilation. When CO\u2082 rises, it typically means the air is not being refreshed enough \u2014 and that moisture, aerosols, heat, and gases may be accumulating in the same space.<\/p>\n\n\n\n

The 2024 Swiss study showed that ammonia concentrations measured by both mobile and stationary sensors were correlated with CO\u2082, temperature, and relative humidity. Environmental parameters must not be read in isolation: the calf housing environment is an integrated system<\/strong>, and must be managed as one.<\/p>\n\n\n\n

In practical terms, Teagasc guidelines suggest 15\u201320\u00b0C as a useful range for maximising calf performance, at least 5\u20136 air changes per hour, and at least 7 m\u00b3 of air volume per head.<\/p>\n\n\n\n

Ventilation: Essential, but Designed Correctly<\/h2>\n\n\n\n

Technical guidelines agree on one point: ventilation must remove humidity, dust, and gases without excessively chilling the environment or directing draughts onto the calves.<\/p>\n\n\n\n

For positive pressure tube ventilation systems, Ontario guidelines specify a winter reference of 25.5 m\u00b3\/hour per calf or 4 air changes per hour \u2014 whichever is greater. But the system must be properly designed: flow rate, tube diameter, number and size of holes, static pressure, and tube position all determine whether fresh air actually reaches the calves without causing problems.<\/p>\n\n\n\n

Local context also matters significantly. Conditions in the Po Valley differ substantially from those in Ireland or Canada. There are no universal solutions \u2014 only universal principles to be adapted.<\/p>\n\n\n\n

Hutches, Individual Pens, Group Housing: Which Structure Is Best?<\/h2>\n\n\n\n

There is no structurally perfect solution. Every system has advantages and limitations, and the right choice always depends on context.<\/p>\n\n\n\n

Hutches<\/strong> offer good separation and outdoor air, but can expose calves to cold, heat, solar radiation, and high climatic variability.<\/p>\n\n\n\n

Individual pens<\/strong> facilitate clinical observation and feeding control, but can limit social behaviour and, if poorly designed, create stagnant microclimates.<\/p>\n\n\n\n

Group pens<\/strong> encourage social behaviour and movement, but require careful attention to stocking density, age segregation, bedding management, and ventilation. Larger groups can increase the risk of infectious exposure and social stress.<\/p>\n\n\n\n

Closed barns<\/strong> protect against weather events but can accumulate moisture and gases if ventilation is inadequate. Open barns<\/strong> promote air exchange but must avoid direct draughts.<\/p>\n\n\n\n

The question to ask is not “which structure is best?” but: does this structure deliver fresh air, dry bedding, low ammonia, low humidity, and freedom from draughts at calf level?<\/strong><\/p>\n\n\n\n

Five Concrete Actions to Improve Air Quality in the Calf House<\/h2>\n\n\n\n

1. Measure.<\/strong> Ammonia, CO\u2082, temperature, humidity, and air speed must be monitored in the calf’s microenvironment \u2014 not just in the corridor. Spot measurements are useful but may miss peaks and fluctuations.<\/p>\n\n\n\n

2. Manage the bedding.<\/strong> Dry bedding is a barrier against cold, moisture, and ammonia. It must be renewed regularly, kept well-draining, and monitored closely in critical areas \u2014 drinkers and feed points first.<\/p>\n\n\n\n

3. Check ventilation using practical tools.<\/strong> Smoke tests, anemometers, CO\u2082 and NH\u2083 sensors can reveal dead zones or problematic air currents. The goal is uniform air exchange \u2014 not wind blowing directly onto calves.<\/p>\n\n\n\n

4. Control stocking density and group composition.<\/strong> Overcrowding and age mixing increase moisture, environmental contamination, and pathogen transmission.<\/p>\n\n\n\n

5. Adapt management to the season.<\/strong> In winter: protect against damp cold and draughts. In summer: prevent stagnant heat, overheating of hutches, and heat stress.<\/p>\n\n\n\n

Conclusions<\/h2>\n\n\n\n

The scientific literature does not offer a single formula for the ideal calf facility, but it clearly identifies the errors to avoid: stagnant air, wet bedding, elevated ammonia, direct draughts, excessive stocking density, and insufficient monitoring.<\/p>\n\n\n\n

Three operational principles emerge strongly from the most recent evidence.<\/p>\n\n\n\n

Air quality must be assessed at calf level \u2014 fixed sensors can significantly underestimate real ammonia exposure. Even relatively low ammonia levels matter \u2014 risk of pulmonary consolidation increases above 4 ppm. And environmental management can concretely reduce health pressure and drug use \u2014 in one study, peak ammonia above 10 ppm was associated with higher antimicrobial treatment rates in a context where 81.1% of treatments were linked to respiratory disease.<\/p>\n\n\n\n

For farmers, vets, and advisors, the priority is to make air quality a measurable, managed parameter \u2014 treated with the same rigour already applied to nutrition and health.<\/p>\n\n\n\n

The calf house holds the future income of the farm. The milk curves of tomorrow’s cows will be shaped, in part, by the air they breathed as calves today.<\/p>\n\n\n\n

Key References<\/h3>\n\n\n\n
    \n
  • Donlon J.D. et al. A systematic review of the relationship between housing environmental factors and bovine respiratory disease in preweaned calves \u2013 Part 1 & 2.<\/em> The Veterinary Journal, 2023.<\/li>\n\n\n\n
  • Van Leenen K. et al. Study on 60 farms and air quality. Preventive Veterinary Medicine.<\/em><\/li>\n\n\n\n
  • Bonizzi S. et al. Air Quality, Management Practices and Calf Health in Italian Dairy Cattle Farms.<\/em> Animals, 2022.<\/li>\n\n\n\n
  • Swiss study on mobile vs stationary sensors. Animals<\/em>, 2024.<\/li>\n\n\n\n
  • Swiss study on antimicrobials and air quality. Preventive Veterinary Medicine<\/em>, 2019.<\/li>\n\n\n\n
  • Teagasc. Calf Housing.<\/em> Technical guidance.<\/li>\n\n\n\n
  • AHDB. Youngstock housing \u2013 Temperature, humidity and ventilation.<\/em> Technical guidance.<\/li>\n\n\n\n
  • EFSA AHAW Panel. Welfare of calves.<\/em> EFSA Journal, 2023.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"

    Guest post by Fabiana Surace, CMO and Environmental Scientist at Cynomys Air quality in calf housing is often treated as a secondary concern. Colostrum, nutrition, hygiene, health protocols \u2014 everything else seems more urgent, more measurable, more immediate. Yet the most recent scientific literature tells a different story: the air calves breathe \u2014 especially at […]<\/p>\n","protected":false},"author":2,"featured_media":9858,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[98,99],"tags":[],"class_list":["post-9860","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-animal-welfare-en","category-productivity-en"],"_links":{"self":[{"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/posts\/9860","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/comments?post=9860"}],"version-history":[{"count":1,"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/posts\/9860\/revisions"}],"predecessor-version":[{"id":9861,"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/posts\/9860\/revisions\/9861"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/media\/9858"}],"wp:attachment":[{"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/media?parent=9860"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/categories?post=9860"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.cynomys.it\/en\/wp-json\/wp\/v2\/tags?post=9860"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}