2 BOVINE OBSTETEICS 



may be diminislied to such an extent as to make this a 

 valuable method of breeding. 



The Holstein usually bears the first calf at tvi^o to two and 

 one half years, when lactation begins. The animal, therefore, 

 is served when fifteen to twenty months old. It is not rare — 

 in fact, it is the rule — to get three thousand quarts of milk at 

 the first lactation, the quantity increasing to six thousand 

 quarts and more with the second calf. On an average, the cow 

 reaches puberty at ten months. Nevertheless, it may occur at 

 five to six months and conception take place. Some years ago 

 I performed embryotomy in a thirteen months old heifer. 

 The calf was of normal size and too large for this female, and 

 for this reason embryotomy was performed. The calf without 

 intestines and skin weighed fifty pounds. The heifer stood the 

 operation well, and became a good milker. 



The best age to serve the cow may -be said to be at 

 one and a half to two years. 



During puberty, at certain intervals, ripe ova leave the 

 ovary, which, on reaching the Fallopian tube, either are fer- 

 tilized or succumb, depending whether coition takes place or 

 not. This process, characterized ly a series of phenomena, is 

 known as oestrum. Of the visible signs one may mention : 

 The whole behavior changes ; the cow runs about with the tail 

 elevated, bellows and rides other cows ; she may leave the 

 pasture to get near the bull ; appetite as a consequence of the 

 excitement is diminished, and the urine is passed in small 

 quantities. The local examination reveals hypersemia of the 

 genital organs, especially the vulva ; it is swollen, and in 

 animals with light skin a slight redness is noticeable. Now 

 and then a little blood or reddish mucus flows from the vulva, 

 to adhere and coagulate on the long hair of the inferior 

 commissure. At times the hemorrhage is considerable, so that 

 it may be termed a true menstruation. (Numan.) 



The udder also changes, showing some swelling. During 

 the period of lactation the quantity of milk decreases and its 

 character changes ; it does not churn well and resembles 

 colostrum. Occasionally oestrum is only recognized by a small 



