Aim to have rams and bucks in a body condition of 3.5/5.0. Overly fat males are less sexually active and more prone to heat stress. Shear rams so that they have 3 to 4 months of wool at joining.
Testical size is a good indication of sperm-producing ability and more emphasis should be placed on it when selecting males.
Read article about sperm production in rams
View YouTube video of ram sperm