456 



EXPERIMENT STATION RECORD. 



creaiu deterinincd by Fjord's control centrifuge. In this way 70 to 00 

 examinations of tlieniilk of eacli cow were made annually, and from these 

 figures the yearly averages were calculated. During the last 2 years 

 the determinations were excluded which were in;tdc directly after calving 

 or toward the end of the lactation i)erio(l, when the yield fell below 8.8 

 lbs. a day. The averages for the whole herd from 1888- '!lo, inclusive, 

 were 5.3, 5.5, 5.5, 4.8, and 4.9 per cent of cream, ^ respectively. The 

 author states that there is no reason to believe that the milk had become 

 thinner during the last 2 years, but the decrease must be due to the 

 difierence in the method of procedure. 



The average per cent of cream in the milk of individual cows during 

 the different years varies less than might be expected. For 75 per 

 cent of the cows the variations are within 0.5 per cent of cream (about 

 0.3 per cent fat), the extreme variation of 1.2 per cent (0.7 per cent 

 fat) occurring with only 3 cows. 



The influence of the age of cows upon the quality of milk is indicated 

 by the results summarized in the following table, which is based on 

 the averages of 5 years' observation : 



EeJation of age of cows 1o conqiosition of milk. 



Age of 



C0W8. 



Tears. 

 2 

 3 

 4 

 5 

 6 

 7 



Number 

 of cows. 



Cream 



above or 



below herd 



average. 



Per 



cent. 

 -fO.l 

 +0.1 

 +0.1 

 0.0 

 0.0 

 —0.1 

 —0.1 

 —0.1 



Cream be 

 low herd 

 average. 



Per cent. 

 0.2 

 0.1 

 0.3 

 0.3 

 0.6 

 0.6 

 0.9 

 0.5 

 0.4 



The average effect of the quantity of milk given on the quality is 



shown below : 



Relation of yield of milk to composition. 



aDamsh potiud (1.1 lb. avoirdupois). 



The results seem to warrant the conclusion that younger animals 

 give somewhat richer milk than older ones, and that cows at the age of 



'One per cent of cream as found by the control centrifuge corresponds to 0.59 to 

 0.64 per cent, or about 0.6 per cent of butter lut. 



