Experiments have shown that, by the use of electric light, sheep in the Northern Hemisphere can be made to breed at the same time of the year as sheep in the Southern Hemisphere. When ewes are taken across the equator from north to south, they change their breeding season to correspond with the hours of daylight. The daylength is also a factor with the production of sperm in the ram but does not seem to be in other animals. Temperature the introduction of Bos indicus cattle into the tropical areas of Australia is an example of using climatically adapted animals in order to maintain fertility and hence production High body temperatures produced in rams by high summer temperatures is a cause of poor quality semen. This also affects semen formation in bulls.
High temperatures can also affect mating with reduced sexual activity.
Conception rate is also reduced. This affects the number of offspring born. In males, the ability of the scrotum to reduce the temperature of the testes sufficiently to produce sperm of sufficient number and viability is severely restricted. It is important, therefore, to have both climatically adapted animals and to provide conditions conducive to proper spermatogenesis to ensure maximum fertility. Disease Disease as a factor that can affect the fertility of farm animals can be related to nutrition, climate, management and genetics.