A.— NORMAL PREGNANCY. 



I. 



CHANGES TAKING PLACE IN THE UTERUS FROM 

 CONCEPTION TO DEVELOPMENT OF YOUNG. 



1.— (Estrum and Conception. 



The development of the young begins as soon as the 

 mature ovum comes in contact with the vitalizing fluid. In 

 the female an ovum capable of fecundation is only found at 

 the age of puberty. 



The age of puberty in the cow varies. In the finely bred 

 animal this period may be induced to set in earlier by inten- 

 sive feeding, proper care, and careful selection of the parent. 

 It even may become inherited, provided the succeeding genera- 

 tions live under the same favorable conditions. Puberty of 

 the cow is usually present some time before the animal is 

 allowed to be served. From the agriculturist's standpoint, it 

 is desirable to have the first calf come in the two-year-old 

 female. Some even require the heifer to be three years old 

 before she gives birth. A great many points are in favor of 

 the latter age. Experience teaches that delivery is easier 

 when the pelvis is not too young and the various diameters are 

 in proper relation to each other. At the same time cows 

 develop better, thus being of greater value in old age, doing 

 good service until ten to twelve years old. 



The act of parturition in the two-year-old is often difficult 

 on account of the narrow and juvenile pelvis, and the value of 

 the cow deteriorates sooner. The dairyman, especially one 

 with limited capital, demands the first calf at two years, in 

 order to utilize the milk as soon as possible. "When fed and 

 cared for properly, the disadvantages of an early pregnancy 



