Managing the Atmosphere of Your Nursery
Managing the atmosphere of the nursery is essential to limit mortality and promote growth of calves. The atmosphere encompasses 5 main points :
- Bedding (surface, volume...).
- Hygiene.
- Ventilation.
- Watering.
- Feeding.
Here we will discuss how to consider the atmosphere of the nursery and which levers to activate to improve it and thus ensure the well-being and optimal growth of calves.
Risks in case of poor atmosphere
A poor atmosphere is the primary risk factor for respiratory disorders. It is estimated that for each sick calf, the farmer must spend at least €150 in veterinary fees. Moreover, this will affect their growth (notably lung development) and their career in the long term.
A poor atmosphere can also cause diarrhea due to the development of environmental germs and thermal stress. A defective atmosphere thus leads to an increase in calf mortality and impacts their growth as well as their future dairy career.
In case of poor ventilation, breathing stale air can also be dangerous for the farmer.
Finally, a poor atmosphere causes faster aging of the building.
Points to consider
Orientation
The building is oriented according to the prevailing winds. These depend on each region, so it is necessary to check the rose of the winds for the concerned region and place the building perpendicular to them. Thus, the building will be more easily ventilated and will benefit from the wind effect.
It is also necessary to ensure that the site around the building is clear. It is recommended that there be no obstacles within 20 meters of the building.
Ventilation without drafts
Air renewal is necessary for a healthy atmosphere : it allows the evacuation of water vapor (breathing, excretion…) and harmful gases (NH3, CO2…). However, this ventilation must be done without drafts! These can alter the perceived temperature.
Thus, all four sides of the building should have openings, especially for summer. When the building is wider than 20 meters, it is recommended to have a ridge vent, i.e., an opening at the highest point of the roof to benefit from the chimney effect.
There is no standard to limit these drafts, only recommendations from the breeding institute. Two periods with two different air velocity thresholds are distinguished :
- In winter, a maximum air velocity of 0.25 m/s is accepted to avoid chills.
- In summer, a higher air velocity is tolerated, up to 1 m/s on average.
A common mistake is to close everything in winter to keep the heat. This practice is absolutely to be avoided because it prevents air circulation. Water vapor and harmful gases would accumulate and thus amplify health problems in the calf.
Lighting
Light is especially important for calves' well-being and for better drying of the straw. At least 100 lux is recommended for calves.
Thermal comfort
Calves are less sensitive to cold than to heat. A temperature above 10°C is still recommended for the first weeks. The older the calf grows, the more it can tolerate cold. Optimal temperatures depend on age. Indeed, at birth, the calf is still a monogastric and its stomach produces much less heat (60 W) than an adult cow (1200 W). Drafts and large temperature differences should also be avoided : limited to 5°C in winter.
However, calves are more sensitive to heat and temperature fluctuations. The thermometer is a good reference. A thermo-hygrometer is even more recommended to also have relative humidity. The maximum acceptable temperature for a calf indeed depends on this humidity. The thermometer can be placed two meters above the calf so it is not touched, and above the alley (headlocks), so as not to disturb the farmer during straw cleaning.
It is also necessary to avoid non-insulating materials such as concrete or metal sheets and rather opt for wood. Also avoid placing calf pens against non-insulated walls.
For any new construction :
- Roof insulation is necessary as it is the main source of heat radiation in summer and cold in winter inside the building.
- Light should be introduced laterally so that calves do not get too hot.
- A removable cladding can also be used, which will be closed more in winter but opened more in summer to allow air renewal. However, be careful that the cladding is not too low to avoid cold air drafts.
If these natural solutions are insufficient, fans can be used and, as a last resort, coupled with misters. Misters must be used with fans to avoid humidity accumulation in the building, which would promote the appearance of environmental germs.
Temperature differences between day and night should be limited if possible to 5°C in winter and 8°C in summer.
Humidity
According to the breeding institute, relative humidity should not exceed 75%, the threshold beyond which environmental germs develop the most.
Bedding surface and volume
Recommendations for surface and volume per calf depend on the age of the calf and the type of housing. Below is the example for strawed areas.
| Age | Total surface
(m²/head) |
Of which strawed area
(m²/head) |
Optimal air volume needed
(m3/head) |
|---|---|---|---|
| 0-2 months | 2.5 | 2 | 5 to 7 |
| 2-6 months | 3 | 2 | 10 to 12 |
| 6-12 months | 5 | 2.5 | 15 |
| 12-18 months | 6 | 3 | 20 |
| 18-24 months | 8 | 4 | 30 |
| > 24 months | 10 | 5 | 35 |
To reduce volumes, removable false ceilings can be used.
Remember to regularly renew the straw and check that it remains dry.
For more information on good bedding conditions for calves, see the page Improving growth of calves from 0 to 3 months.
Others
The building must not be filled with dust and the CO2 level must also remain adequate to avoid poor lung development in the calf and growth delay.
Atmosphere diagnosis
If the farmer wishes to evaluate the performance of their building, avoid production drops and health problems during critical periods, and is interested in going further in understanding the atmosphere of their building, they can carry out an atmosphere diagnosis.
This atmosphere diagnosis allows to :
- Improve animal welfare and working comfort.
- Increase animal production performance.
- Reduce costs related to animal health.
- Anticipate building evolution in relation to climate change.
The atmosphere diagnosis allows the farmer to be supported and to refine their plans, for example for expansion. After a questionnaire to identify the issue and the farmer's practices, the expert, using sensors, will collect data at several points in the building. They will then analyze this data to develop with the farmer an action plan adapted to their case.
A follow-up visit can be carried out one year later, under weather conditions similar to those of the first diagnosis, to verify the impact of changes made and make adjustments if necessary.
The consulting company Eilyps offers, for example, the BREEDER AIR diagnosis. For more details, click here.
Further reading
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