TWO SYSTEMS OF FEEDING DAIRY COWS 



11 



a unit of milk produced. Reasonably accurate production records, such as are kept 

 in herd improvement association work, can be used to ascertain this. 



Milk Production from Year to Year 



The question is often asked concerning certain methods of feeding and manage- 

 ment, "How do the cows hold up from year to year in production ?" Unfortunately, 

 only a small number of year to year comparisons are available from this study; 

 five from the high roughage group, and seven from the low roughage group. These 

 have been adjusted to a mature cow basis®, and the actual and percentage incre- 

 ments or decrements from year to year are shown in Table 7. 



Table 7. — Changes in Milk Yield of Individual Cows from Year to Year. 



Cow 

 No. 



Milk Yield^ 

 Pounds 



Change from Year to Year 

 Pounds Per Cent 



139 

 Average 



33 



99 

 121 

 126 



138 

 141 

 Average 



*Corrected to a 30S-day, farrow, mature cow basis. 



Although both groups maintained their milk yield from year to year, the high 

 roughage group did so only by a very narrow margin, while the low roughage 

 group showed a substantial increase. Had there been available the same number 

 of comparisons for both groups it is possible that there might not have been quite 

 such a disparity between them in this respect. Because of the relatively few records 

 caution should be used in interpreting this result. 



*The adjustments have been made by using the factors for that purpose published by Turner, Rags- 

 dale and Brody in Missouri Station Bulletin No. 221 , page 8, Table 2. 



