Sheep are naturally seasonal breeders, and respond to decreasing daylight hours. That is, the proportion of ewes cycling, the number of ova shed and the libido and fertility of rams all tend to increase as daylight hours decrease. Most British breed sheep are highly seasonal breeders, but Poll Dorsets and Merinos, through generations of selection for out of season breeding, will cycle and conceive over a much longer period. Even so, spring joinings usually result in fewer lambs than autumn joinings. Be warned though that this practice of double annual mating will complicate your sheep husbandry program and record keeping.
Teasers are rams that have been vasectomised or wethers that have been treated with testosterone.
Rams must be in good health and fit for mating . Inspection and preparation of the ram team should begin two months before the start of joining. Their fertility and libido will be enhanced if they are fed 500 gm of lupins daily from this time until joining. Any health problems which cause a fever, such as flystrike or foot abscess, can severely depress ram fertility, and it can be six to eight weeks before semen quality recovers, even though the ram may recover much faster. Similarly, any handling which could cause the rams to become hot should be avoided within the eight weeks prior to joining.