CLINICAL ASPECTS OF STALLION FERTILITY

The studies described in this thesis investigated the factors that can affect the fertility of stallions. The introduction describes the mal e gamete and the processes that occur during maturation of sperm and f ertilization. Methods to evaluate the quality of sperm and ova are the n discussed. Fertility can be expressed in various ways and is also af fected by many factors such as the stallion, the mare and management f actors. The fertility of stallions is usually assessed a good year aft er they have served mares, because then the number of foals is known. However, it would be preferable to be able to predict a stallion's fer tility before he is put to stud. To this end, it was investigated whet her there is a relationship between a number of sperm parameters and t he percentage of non-return after the first cycle. The endocrine contr ol of reproduction is briefly described because hormonal factors can a lso influence the reproductive potential of stallions. The venereal di seases that are important for regulations concerning the international deserves further investigation. The minimum requirement for a stud st allion is that the stallion should produce sperm of adequate quality a nd should be able to fertilize mares.