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POUNDS OF MILK 



Figure 4. Distribution of a sample of 179 pairs of raised and purchased cows 

 according to production of 4 percent fat-corrected ntilk, the level of milk pro- 

 duction corrected for age of the animals. 



tested statistically, was not significant.'' Therefore, it was concluded that 

 for this sample of cows, raised and purchased cows that were comparable 

 with respect to age, breed, date of freshening, management, and fat con- 

 tent, produced about the same quantity of milk. In this way, they were 

 alike in quality. 



A comparison of the levels of milk production for the purchased and 

 raised cows in the sample of farms surveyed substantiates the conclusion 

 that these cows are similar in their ability to produce milk. The 24 herds 

 that contained only raised cows averaged 8,343 pounds of 4-percent fat- 

 corrected milk. Herds that contained only purchased cows averaged 8.114 

 pounds. The difference of 229 pounds in favor of herds made up of raised 

 animals was small. It was less when only herds of the same breed were 

 compared. Twelve Holstein herds made up of raised cows averaged 8,321 

 pounds of 4-percent fat-corrected milk. Twenty Holstein herds that con- 

 tained some purchased cows averaged 8,486 pounds of 4-percent fat- 



^ A Student's t test was used and difference in average production was not sig- 

 nificant at the 5-percent level. 



17 



