I02 Bulletin 152. 



Table VII places in ready comparison the records of those cows 

 which have been tested more than once. Nine were tested twice 

 during the same period of lactation and all of these gave a less 

 amount of fat on the second test than on the first except No. 39. 

 In this case she gave less milk than at the first test, but her per 

 cent of fat was greater by .53 of i per cent, so that the total fat 

 was also greater. (She was in an " Economic Food Test " the 

 second time.) Three gave more milk and two a higher per cent 

 of fat on the second test than on the first. The average produc- 

 tion of the nine on their first tests is, — 386.042 pounds of milk, 

 3.53 percent fat and 13.829 pounds of fat. Their average on the 

 second tests is, — 381.91 pounds of milk, 3.27 per cent fat and 

 12.128 pounds of fat. Accordinglj^ we may infer that, as a rule, 

 a cow which has been forced to her utmost for seven days cannot 

 again be made to reach the same point either in production of 

 milk or fat during the same period of lactation. 



"EQUIVALENT RECORDS." 



According to the scheme adopted by the Holstein-Friesian 

 Association for the admission of cattle into the Advanced Registry, 

 each two-3^ear old must have produced 7.2 pounds of fat, three- 

 year old 8.8, four-year old 10.4, and each cow, five years old or 

 older, 12 pounds of butter-fat in seven days. It is considered by 

 the Association that a two-3'ear old which produced 7.2 pounds, 

 a three-year old which produced 8.8 pounds, or a four- 

 year old which produced 10.4 pounds of fat would, when 

 she reached the age of five or over, produce 12 pounds. Or, in other 

 words, a yield of 7.2 pounds of fat by a two-year old, 8.8 by a 

 three-year old, or 10.4 b}' a four-year old is equivalent to 12 

 pounds when the heifer reaches full age. To make this plan 

 good there must be a gain of 1.6 pounds of fat during each 

 succeeding year, which requires an average gain of .13/^ pounds 

 per month and .00438 pounds per day. In other words, the gain 

 from two to three 3^ears must be 22.2 per cent, from three to four 

 years 18.2 per cent, and from four to five j^ears, 15.4 per cent. 



In Table VII in the column headed ' ' Per cent of Gain or Loss ' ' 

 is given the actual gain or loss per cent sustained b}^ the cow 

 from one test to another. In the column headed ' ' Per cent of 



