558 



Scientific Proceedings, Royal Dublin Society. 



Having found a reliable method of determining the average fat percentage 

 for a short period, it remains to consider its application to the entire lactation 

 period— the abnormal periods, as .found during the 1916 investigation, 

 being avoided. For some weeks after calving, and for several weeks at the 

 end of a lactation, the quality of a cow's milk is above the average for 

 the whole lactation, as in diagram V. At the beginning of the interval 

 between these two periods it is below and at the end above the average. 

 There must, therefore, be a short period within this interval when the 

 quality of the milk is close to the average for the whole lactation. Evidently 

 this period occurs about midway between the extremes, but it is necessary in 

 this connexion to investigate data from other sources. 



2 3 4 56789 



Diagram V. — Percentage of fat in milk during a lactation period. 



10 months 



From figures compiled by the Department of Agriculture, from the 

 returns -of the Irish creameries, it is found that the milk required to make a 

 pound of butter in the month of August is approximately the quantity 

 required on the average throughout the year. The following are the 

 figures: — 



Gallons of Milk required to make a Pound of Butter. 



