THE BREEDING SEASON 55 



53. (Estrum. The oestrum may be referred to as 

 the heat proper and represents the time when the female 

 will receive the male. It is during this period that the 

 peculiar symptoms well known to practical breeders are 

 exhibited. This phase is characterized by unusual 

 activity on the part of the animal. Great restlessness, 

 constant movement and often great mental excitement 

 are observed in animals which are in heat. The genital 

 organs become congested. The mammary glands in 

 animals not suckling young increase in size. The external 

 genitals, particularly the vulva, become swollen and red 

 and mucous and bloody excretions flow from the genera- 

 tive organs. In many animals, there are frequent at- 

 tempts at urination. The female sometimes utters loud 

 cries or grunts, as in the sow. Cows, ewes and sows 

 lose appetite, and get " off feed," often losing in weight. 

 In all meat-producing animals, when the females are 

 fattened for the markets, this is an economic loss to the 

 feeder. In some sections, the larger feeders have spayed 

 the heifers intended for fattening and thus prevented 

 this loss. If the animal is bred and conception occurs, 

 these periods of excitement are prevented, but pregnant 

 fat animals are less valuable on the market and are always 

 discriminated against by the buyer. 



54. Metcestrum. The oestrum is followed by a 

 gradual subsidence of the symptoms which characterize 

 this period, provided coition does not take place and 

 pregnancy result. In the latter case, oestrum is followed 

 by gestation. If the female is not bred to the male during 

 oestrum, the sexual excitement of the period gradually 

 passes away and the animal returns to a normal condition. 



55. Diosstrum. The dioestrum represents the time 

 of rest for the generative system between the periods of 



