4 BULLETIN &45, U. S. DEPARTMENT OF AGRICULTURE. 



noticeably during the routine treatment. After several years of the 

 routine treatment cow 17 was given an unusually long dry period 

 before calving, and cow 201, a more liberal ration for some weeks be- 

 fore calving. In both cases the subsequent milk yields were 

 markedly increased. (See p. 13.) 



The increase in the milk yields of these cows is due in the one 

 case to the more liberal ration supplied before the calf was born; 

 and in the other to the long dry period with a supermaintenance 

 ration. The rations fed after calving bore about the same relation 

 to the milk yield as they had in previous years. It may be added 

 that the milk yield for the first few weeks of lactation is not very 

 closely dependent on the contemporaneous food supply (2). 



5 6 1 O 9 10 



HUNDRED POUNDS OF MILK 



Fig. 2. — Influence of the length of the dry period and of the ration fed during that period 

 on the subsequent milk yield in the case of cow 201. The columns represent the pounds 

 of milk given jn the first clear calendar month after calving in the years indicated. 

 Before calving in the years 1914 to 1917, inclusive, this cow was fed the routine ration 

 for dry cows at Beltsville ; her dry periods averaged 50 days. Before calving, in Decem- 

 ber, 1918, she was given a dry period of 78 days, and during the last 40 days of this 

 period was fed a much more liberal ration than the previous one. (See pp. 13 and 14.) 



The course of events which these two cows illustrate is typical. 

 Several similar histories could be presented. Indeed, it has been the 

 rule on this farm that greatly increased milk yields were obtained 

 when cows from the general herd were dried off two months or more 

 before they were due to calve and fed liberally during the dry period. 

 Cows 17 and 201 were selected as examples, not because the downhill 

 course of their milk yields on the routine treatment was particularly 

 rapid or the subsequent recoveries particularly marked, but simply 

 because they had been freer from disease and from disturbing ex- 

 periments during their stay at Beltsville than others which might 

 have been selected. It is, therefore, a very moderate statement of 

 the case to say that average and high-producing cows often do not 

 maintain anything like their optimum milk yield when they are bred 

 to calve once a year and fed for several years approximately accord- 

 ing to the most liberal of the American feeding standards, even 



