140 Studies in Milk Secretion 



Porcher^ found that on giving phloridzin to lactating goats and cows 

 the yield of milk for the following periods was decreased in amount. 

 Paton and Cathcart^ by the same means decreased the amount of glucose 

 available in the blood of lactating goats and found that this resulted, 

 not in a decrease of the percentage of lactose in the milk, but in a 

 diminished secretion of milk together with amounts of lactose, nitrogen 

 and ash formed. They found that the lowest secretion of milk took 

 place on the day that the largest output of sugar occurred in the urine. 

 Rose^ found that the volume of milk secreted fluctuated inversely 

 with the amount of phytin in the food and that the composition was 

 not altered except that the percentage of fat increased when the phytin 

 was administered. 



Methods. 



The object of our investigation was to study the changes in the 

 yield and composition of the milk w^hich followed a sudden change in 

 nutrition. The sudden changes in nutrition were brought about by 

 the administration of phloridzin together with the control of the food 

 supply. 



Well fed goats were used in all the experiments and care was taken 

 that they had continual access to an abundant supply of water. They 

 were milked regularly at different intervals three times a day ; records 

 were kept of the yield at each milking in c.c. and the percentage fat 

 in each milking was estimated by the Gerber method. The daily figures 

 only are given in the tables below; the percentage fat for each day 

 being calculated from the total fat and daily yield. 



Experiments. 



Three series of experiments were performed : (a) food was withheld 

 for a short time and then a plentiful supply given ; (6) food was withheld, 

 phloridzin was injected and shortly afterwards a plentiful supply of 

 food given; (c) phloridzin was injected into goats under perfectly 

 normal conditions of feeding. 



Series (a). Food was withheld from well nourished goats for a few 

 days and then an abundant supply given them. Two experiments 

 were undertaken and Table I below shows the results obtained. 



1 Arch. Interval, de Physiol. T. vra, 1909. 



' Jour, of Physiol. Vol. xun, 1911. 



» New York State, Sta. Tech. Bui, No. 20, 1912. 



