Apr. 15, 1919 Quantity and Composition of Ewes' Milk 21 



to ascertain the factors which influence growth, since analyses of the 

 milk of individual ewes differ widely. In the first year's work, which 

 was preliminary in nature, five breeds of ewes were studied, an estima- 

 tion of the quantity of milk given by each ewe was made every seven 

 days, on two ewes of each breed. Chemical analyses of the samples of 

 milk taken in lo-day periods after lambing were made for a period of 

 70 days. The gain of the lamb was recorded every seven days. The 

 chief objections showing up in the preliminary work were as follows: 

 It became evident that samples of milk for analysis and total quantities 

 of milk ought to be taken at the same period, or as near thereto as pos- 

 sible. The experiment included only two ewes in each breed, and in 

 some cases one might give an abnormally high or low milk yield, which 

 would show unfair averages in the breed. Still another factor entered 

 into the work. A period of 70 days proved too long, for lambs need 

 access to grain early in their life, and as grain was fed to them this 

 made any correlation of composition of milk and growth futile. All 

 the above difficulties were eliminated by the following procedure adopted 



in this work : 



PLAN OF INVESTIGATION 



It vv^as realized that any work on the study of the milk of ewes must 

 include a number of ewes before a fair average of the milk constituents 

 could be obtained. However, in this work the difficulty becomes very 

 evident, for with a great number of ewes the work becomes so labo- 

 rious that the use of a great number in the experiment is prohibitive. 

 The aim was to choose three ewes which showed characteristics of the 

 average ewe of the particular breed. This was done by starting with 

 four ewes of each breed and continuing with the three that showed 

 the nearest to the normal milk yield for the breed. Six breeds of ewes 

 and three ewes from each breed were used in this experiment. The 

 period of investigation continued for 50 days. Every 10 days after 

 lambing the total quantity of milk was recorded, and samples of milk 

 were taken. The weight of the lamb was taken at birth and every 

 10 days thereafter, from which the gain was calculated. 



METHODS USED IN OBTAINING MILK SAMPLES 



In determining the total milk yield of each ewe the lamb was separated 

 from the mother ewe at 6 o'clock in the morning. At 7 it was allowed 

 to suckle the ewe. This was done in order to start all ewes on a 

 uniform basis. At frequent intervals during the 24-hour period, which 

 began after the lamb suckled the ewe at 7 o'clock, the lamb was weighed, 

 allowed to suckle, and reweighed, on a balance weighing accurately to 

 I gm. The sum of the differences in the lamb's weight before and 

 after suckling the ewe during the 24-hour period gave the total yield 

 of milk. In this manner all the milk was obtained without causing 

 any nervousness on the part of the ewe, and the results gave a good 



