Prenatal Mortality in Farm Animals

Contents Introduction Methods of study Extent of prenatal mortality Causes of prenatal death Conclusion I. INTRODUCTION The division of prenatal development in farm animals into three periods, that of the ovum, that of the embryo and that of the foetus is now a widely used convention. However, the difficulties involved in determining accurately the time of death and the difficulties involved in deciding the limits of these periods rob them of their value as a basis for the classification of prenatal mortality. The dividing limits of these periods were defined by Winters, Green & Comstock (1942) as being the time of attachment, which they reported as occurring in the bovine animal at about the eleventh day after fertilization, and the time when the formation of the major tissues and organs is concluded, which they arbitrarily put at 45 days following fertilization. However, there would appear