25 25 LOHMANN TIERZUCHT › MANAGEMENT GUIDE Negative influences Laying hens are very resilient and can adapt to most weather conditions however when these become extreme extra measures should be taken. Plumage condition Draughts Low temperatures High temperatures Plumage condition plays a big part in adaptation to weather conditions in alter- native systems and should be considered when making changes to ventilation and nutrition. Draughts can be very detrimen- tal to the birds and lead to an increase in mortality, smother- ing and floor eggs. Draughts should be avoided and air flow at bird level carefully monitored. Well-designed winter gardens and wind protection devices can be used to reduce the impact of draughts in houses with open pop holes. Low temperatures can lead to increased con- sumption to maintain energy and mainte- nance levels within the hen. High temperatures above 28 °C begin to put additional strain on the metabolism of the laying hen. When these situations are unavoidable additional ventilation should be imple- mented and air flow carefully monitored supplying electrolytes for a short period can also be beneficial. These are especially harmful for young chicks and will affect their health and well-being. Toxic gases & Dust If problems in the ventilation of the barn or aviary houses occur, it is advisable to consult a specialist. Minimum Air Quality Requirements O 2 over 20% CO 2 under 0.3% CO under 40 ppm NH 3 under 20 ppm H 2 S under 5 ppm