conditions, particularly in winter can quickly deteriorate
to the point where livestock (especially young lambs or
recently shorn sheep) risk death. This is caused by one
key factor: energy being drawn from the animal's body at a
higher rate than the animal can sustain.
The Sheep Chill Index models the heat lost by animals and is derived from air temperature, rainfall and wind speed data. The graph shows different levels of ‘chill’ and can be used to raise alerts if the level exceeds a safe threshold. For example, if conditions are moving into the ‘severe mortality risk’ zone (red area), this is a prompt for stock to have access to shelter.
A key component of reducing lamb mortality is sheltering them from the wind. This can be achieved through strips of perennial grass hedgerows or by leaving stands of trees. For example, a one-metre high hedge row can reduce wind speed by 30-40 km/hr.