MAMMARY GLAND AND LACTATION 



6L 



Goat 515 



Body 5Q _ 

 weight — 



(kg) 40 

 150 

 Plasma Na ^ ^. 

 / /I \ ^40 — 



(m-equiv./l) — 



130 



Plasma K 

 (m-equiv./l) 



Milk K 

 (m-equiv./l.) 



Milk Na 

 (m-equiv./l.) 



Solids-not- ^ H 



fat {%) 7 U 



Yield of 200 - 



solids-not- — 



fat (g) 100 - 



Fat (- ^ 



Fat yield 



Milk yield 

 (kg) 



13 23 2 12 22 2 12 22 

 Oct. Nov Dec. 



Fig. 12B. 



11 21 31 10 20 



Jan. Feb 



conclusive that there is a true inhibition of 

 milk secretion (see Cowie, 1960). In the 

 cow estrogen in sufficient doses depresses 

 milk yield, but its mode of action has not 

 been fully elucidated. In women, estrogens 

 are used clinically to suppress unwanted 

 lactation, but as the suckling stimulus is 

 also removed about the same time, the role 

 of the estrogen is difficult to assess (see 

 Meites and Turner, 1942a). 



It has been well established that proges- 

 terone by itself has no effect on milk secre- 

 tion (see Folley, 1952a), save in the ad- 

 renalectomized animal (see page 612), and 

 so it would appear that the physiologic 

 inhibition of lactation is effected Ijy estrogen 

 and progesterone acting synergistically as 

 first demonstrated by Fauvet (1941b) and 

 confirmed by others including Masson 

 (1948), Walker and Matthews (1949), 



