During the last 30 years science, including the knowledge of reproduction in the domestic animals, has made very great progress. Practical applications have advanced in step with the new knowledge, but the degree to which this progress has benefited the tropical countries has, for various reasons, so far been slight.

The aim of the guideline is to provide veterinarians, and animal production specialists with a useful "vade mecum" for the daily problems of fertility and infertility in cattle. It is intended to cover all phases of the whole reproductive process, starting from its physiology in the male and in the female, and covering natural and artificial breeding, pregnancy, parturition, and the post-parturient period of the dam and calf, up to the point when normal fertility for renewed breeding is regained. Not all aspects will be considered academically, as in most classic textbooks, but emphasis will be laid on those practical problems of greatest economic importance which field workers are regularly confronted with in practice.

All workers with personal experience, and most available reports agree on the point that infertility in cattle is a serious problem in practically all tropical countries. This applies equally to the individual cows of the small farmer, to the whole herds of the larger private owners and to herds owned by "Institutes", including those supported by the government of the country concerned. In some countries the problem mainly affects dairy cattle, but in others infertility is a disaster in beef cattle breeding, whether in small herds or on ranches.

Many detailed survey reports on the practical situation of livestock reproduction place responsibility for the greatest economic losses on the main forms of infertility, namely; too late first calving of heifers; a prolonged calving interval; a short "stayability" or working life (involving premature culling), and high calf mortality.