328 



EFFECT OF INTEKVALS BETWEEN MILKINGS 



After changing back to the old times of milking, the same cows 

 gave 



In May, 1908, in connection with a milking contest at an agri- 

 cultural show in the Transvaal, the writer had a somewhat striking 

 example of the effect of very unequal intervals preceding the milkings 

 upon the proportion of fat in the milk. 



The average of two morning milkings of four cows (milked at 9 

 a.m.) gave 110-2 Ib. of milk containing 2-57 per cent of fat, while 

 that of three evening milkings (at 5 p.m.) of the same animals gave 

 67'7 Ib. of milk containing 5'08 per cent of fat. Here the intervals 

 were sixteen hours and eight hours, and, as the figures show, the per- 

 centage of fat in the milk was approximately inversely as the intervals 

 preceding the milkings. 



To summarise the four sets of figures just quoted, we have 



Intervals . 

 Katio of intervals . 

 Katio of milk . 

 Eatio of fat content 



Intervals . 

 Eatio of intervals . 

 Eatio of milk . 

 Eatio of fat content 



Intervals . 

 Eatio of intervals 

 Eatio of milk . 

 Eatio of fat content 



Intervals . 

 Eatio of intervals 

 Eatio of milk . 

 Eatio of fat content 



15 hours 

 1-66 

 1-51 

 1 



12J hours 

 1-09 

 1-17 

 1 



15 hours 

 1-66 

 1-43 



1 



16 hours 

 2 

 1-64 



1 



and 



and 



and 



a 1 } d 



9 hours. 

 1 

 1 

 1-51 



1 hours. 

 I 

 1 

 1-13 



9 hours. 

 1 

 1 

 1-54 



8 hours. 

 1 

 1 

 1-97 



These figures and many others which have been obtained in the 

 course of the writer's investigations show that the percentages of fat 

 in the milk are approximately inversely as the lengths of the intervals 

 of time preceding the milkings. Collins 1 has deduced the following 

 expression to calculate the probable difference in percentage of fat in 

 morning and evening milk : 



E - M 



e - m 



- 0-2 



where E represents percentage of fat in evening milk, M that in 

 morning milk, e the time in hours between the evening milking and 

 the morning milking, and m the time in hours from the morning to the 

 evening milking. But it would appear that it is the ratio between the 



Proceedings of the Durham Philos. Soc., 1911, pt. 1. 



