Microclimate
A fundamental prerequisite for reliable measurement and interpretation of climate data is the installation of climate sensors at animal height (with protection against being pecked and adjusted to the correct height, e.g. by mounting them on feeding equipment, Figs. 1/2), as well as regular calibration and maintenance.
An animal-friendly barn climate (microclimate) contributes significantly to the animals’ welfare and, at the same time, has a positive effect on their weight gain. The term ‘barn climate’ encompasses temperature, relative humidity, air quality and air velocity. Deviations in the barn climate can pose a risk to animal health², including:
Reduced animal health, which may be reflected in increased susceptibility to disease, such as respiratory infections or poorer hoof health
Increased cardiovascular strain (which, if prolonged during rearing, can lead to organ changes, e.g. heart enlargement)
Weight gains below the target range
Disparity in growth (lack of uniformity) within the herd
Reduced oxygen supply to the organs, resulting in conditions such as ascites – particularly relevant during rearing
Before commencing the animal inspection, the temperature and relative humidity should be checked by looking at the barn computer. At the start of the animal inspection, one should form an initial impression of the air quality and observe the flock’s behaviour. The distribution of the birds can already provide initial indications as to whether adjustments to the ventilation or temperature may be necessary. It is important to ensure that the floor is already pre-warmed and dry when chicks are placed in the house. Depending on the floor temperature, chicks lose up to 50 per cent of their body heat through their skin. As a guide, approximately 30 per cent of the heat is lost to the floor with a thin layer (< 2–3 cm) of bedding (wood shavings), whilst with a thicker layer (8–10 cm) bedding (wood shavings), the figure is only around 5 %2.
The air is fresh and clear; no ammonia or dust is detectable
Concentrations of harmful gases at animal height: < 3000 ppm CO₂, < 10 ppm NH₃ (not exceeding 20 ppm NH₃ at any time), < 10 ppm CO₁, 3
- Relative humidity is between 50–70 %³; for chicks: 50–60 %²
No draughts are noticeable; for chicks < 0.1 m/sec, during fattening 0.2 m/sec in the cooler months, and at high outside temperatures < 2.5 m/sec²
Pre-heated floor, minimal difference between floor and air temperature when chicks are placed in the house2
Even distribution of the flock within the house
Age | Ring rearing | Ring-free rearing with spot heating | Ring-free rearing without spot heating | ||
|---|---|---|---|---|---|
Temperature under the heat lamp (°C) | Ambient temperature (°C) | Temperature under the heat lamp (°C) | Ambient temperature (°C) | Ambient temperature (°C) | |
Day 1 | 38–40 | 24–25 | 38–40 | 29–31 | 36–37 |
Day 2 | 38–40 | 24–25 | 38–40 | 29–31 | 35–36 |
Day 3 | 38–40 | 24–25 | 38–40 | 29–31 |
|
Days 4–7 | 38–40* | 24 (on the day of hatching, temperature +1 °C) | 35–40* | Reduce the temperature by 1 °C each day | Reduce the temperature by 1 °C each day |
Week 2 | approx. 24 | 27–28 | 27–28 | ||
Week 3 | approx. 23 | 25–26 | 25–26 | ||
Week 4 | approx. 22 | 23–24 | 23–24 | ||
Week 5 | 21–22 | 21–22 | 21–22 | ||
Week 6 | 20–21 | ||||
Week 7 | 19–20 | ||||
Week 8 | 18–19 | ||||
Week 9 | 17–18 | ||||
Week 10 until weaning | 10–17 | ||||
* Reduction in heating output by switching off individual heaters, whilst maintaining the total heat output of the active heaters
Table 2: Guide values for house temperature in rearing and fattening (adapted from information on turkey fattening 2021)3
Deviating condition
Dusty
The air appears visibly dusty
Air is described as dusty when the dust concentration exceeds 3
mg/m³ (for comparison, in occupational health and safety: 1–5 mg/m³ → ‘visibly dusty’, e.g. light workshop work)Sources of dust particles: bedding, feathers and skin particles²
Factors that promote the formation of dust²
Temperatures in the barn combined with low humidity
Air velocities (excessive ventilation)
Type of litter and litter moisture content
Bedding quality
Frequent handling of the bedding
Can lead to respiratory problems and fungal infection of the air sacs
Deviating condition
Damp/stuffy
from 70 per cent relative humidity1
Factors that contribute to high humidity in the barn
Bedding that is too damp (slippery, sticky)
Ventilation set too low (insufficient exhaust air capacity)
Extensive use of spray cooling
Damp outdoor conditions
Can contribute to heat stress in combination with high temperatures; this can be recognised, amongst other things, by the animals’ behaviour: animals pant and spread their wings
Measures
If the temperature in the barn is low, increase it -> cold air holds less moisture
Check the ventilation settings and adjust them if necessary
Take additional measures in the event of heat stress14
Top up the bedding and identify the causes of damp bedding, then take action to remedy the situation