78 THIRTIETH ANNUAL REPORT OF THE 



Thursday Morning. 



Meeting- called to order by the President at 10 a. m. 



"WHAT MAKES THE MILK TEST VARY SO?" 



Joseph L. Hills. 

 Director, Vermont Agricultural Experiment Station, Burling- 

 ton, Vt. 



Let us consider this matter under three heads: 



I. Why does the milk delivered by different patrons vary 

 in test? 



II. Why does the milk delivered by the same patron 

 when taken to different creameries vary in test? 



III. Why does the milk delivered by the same patron, at 

 the same creamery, vary one week with another, and one 

 month with another; why does not its quality remain un- 

 changed? 



I. Variation in Tests Between Individual Patrons. 



ist. Why does Smith's milk test differ from that of Jones? 

 Differences of breed, individuality, food, nervous excitement, 

 environment, weather and the stage of lactation may influence 

 the result. Let us sketch some of these. 



BREED. 



Every observing dairyman appreciates that differences 

 in cattle, due to the character of their breeding, are such 

 that some cows give richer milk than others. The Channel Is- 

 land cows have been bred through many scores of years with a 

 specific purpose in view, to make a high grade milk ; and, on the 

 other hand, the cattle of Holland and Scotland have been bred 

 generation after generation more particularly to make a large 

 quantity of milk. While there are exceptions to every rule, 

 still, speaking broadly, Jerseys and Guernseys give richer milk 

 than do cows of other breeds. Smith's test outranks Jones, 

 because long lines of breeding with a definite aim in view 

 have implanted in his animals a tendency toward making a 

 better grade of milk than can Jones' cows. 



