390 



Comparisons between tables I and II would indicate that the 

 decrease between the first and second and the second and third 

 lactation periods in the case of the old cows was due to advanc- 

 ing age. It will be noted that the cost of feed per pound of 

 butter fat remained nearly constant for the three years and did 

 not fall below twenty-two cents per pound, while in the case of 

 the younger cows there was a greater decrease in cost. 



In table III the cows that were four years old or over when 

 they came to the farm are referred to as " original scrubs ; ' ' those 

 that came as yearlings and calves, or were dropped on the college 

 farm, are designated as ' i developed scrubs, ' ' while the terms Hoi- 

 stein x scrub, Guernsey x scrub and Jersey x scrub refer to the 

 first generation heifers out of scrub cows and by purebred sires of 

 those breeds. The comparisons are made between cows falling 

 into these different classes and in this table the younger animals 

 are not compared to their own dams but to all of the old cows 

 taken as a group. In the comparison between the developed 

 scrubs and the originals it will be noticed that the former have 

 produced 13% more milk and 12% more butter fat while little 

 difference is noted in percent of fat or length of lactation period. 

 With seven cows in each group and the number of lactation 

 periods, twenty-five and twenty-nine respectively, this increase 

 is worthy of note. A direct comparison can not be made between 

 dams and daughters in this case as but one record made by a 

 scrub daughter of one of the old cows is available. The first 

 generation of Holstein grades show an increase of 64% in amount 

 of milk, 41% in pounds of fat, 15% in length of milking period 

 and a decrease of 14% in percent of fat in milk. 



The first generation Guernsey grades show an increase of 12% 

 in quantity of milk, 6% in pounds of fat, 1% in length of lac- 

 tation period and a decrease of 5% in percent of fat in milk. 

 The smaller increase shown by these grades can not be charged 



TABLE III AVEEAGE YEAELY EECOEDS SHOWING INFLUENCE 



OF FEED AND MANAGEMENT AND THE USE OF PUEE 



BEED DAIEY SIEES ON PEODUCTION 



