CHAPTER IV 

 GESTATION AND LACTATION 



FROM the time the egg is fertilized until the young 

 animal is able to live an independent life covers a period 

 which is of the greatest importance to the growth and 

 development of the individual and the mother. During 

 this time all the physiological activities which are con- 

 cerned with growth are at maximum efficiency; at no 

 other period in the life of the animal is growth so rapid. 

 Not only is the rate of growth very rapid, but the food is 

 utilized much more economically. The stage of develop- 

 ment which takes place in the uterus of the mother is 

 the period of gestation. The period of lactation is the 

 time during which the mammalian animal elaborates 

 milk. 



GESTATION 



64. Indications of pregnancy. If the animal comes 

 normally in heat and is bred to the male during the heat 

 period, conception occurs in the natural course of events 

 and pregnancy begins as a result of successful conception. 

 Significant physiological changes occur which are recog- 

 nized by the breeder as evidences of pregnancy. Preg- 

 nant animals do not normally come in heat. The chief 

 evidence, therefore, that an animal is "in foal," "in calf," 

 " in pig," or "in lamb " is the cessation of the periodic 

 appearance of the symptoms accompanying the period of 

 the oestrum. If after breeding the mare does not come in 



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