Australian sheep breeders have a world reputation for breeding sheep most suitable for any climate. Large strong wool merinos are found in the arid zone as they are resistant to dust, abrasion and vegetable matter. Merinos are the most numerous breed in NSW and in the arid pastoral zone, the only breed. It is basically, a “maintenance free” sheep but in hot humid weather encourages wool rot, foot rot and fly strike. On the perimeters of the desert sheep breeding is restrained by excessive autumn temperatures and temporary sterility is brought on in rams suffering stress some weeks prior to mating.
Pastoralists have trouble maintaining their sheep populations in the arid zones in times of drought and droughts can last a number of years. The density of the sheep numbers increase as one moves south. In the southern districts, merinos are found in the coldest parts as provided they have access to food and have a reasonable fleece they will survive snow storms and blizzards. Smaller fine wooled sheep are found on the colder parts of Australia for example, tablelands.
The fine wool is more valuable on a weight basis but the fleece is lighter. Genetically, fine wool is linked with a small body size and cold wet conditions will cause sheep to grow fine wool even when they have been bred on the plains.