60 W. Hartwig 



opinion sometimes expressed, that the age of the animals 

 would decrease as a consequence of higher productivity. 

 Mannes (1947) and Dietrich (1956) succeeded in proving, in the 

 course of their researches on red-pied coloured cows in the 

 Rhineland and on black-pied cows in Saxony, that long-lived 

 cows produce more milk, even during their earlier years, than 

 those having a short period of produce, and that highly pro- 

 ductive cows live to the greatest age. From the results shown 

 below it can be seen that there has been a general rise in the 

 average lifespan of herd-book animals, even though the pro- 

 ductivity has also risen considerably. 



Table II 



Average age of black-pied cattle of the Middle-Weser 

 association of cattle breeders (from bottcher, 1952) 



No. of Average lifespan 



Date cows iv^s.) 



1930 420 5-5 



1935 752 6 



1940 1,094 5-9 



1945 1,618 6-5 



1949 1,722 6-9 



The rise in the average age in 20 years was 1 • 4 years. Ziegen- 

 hagen undertook the same examination of the Anglia breed 

 (Table III). 



Table III 



Average age of Anglia cattle (from Ziegenhagen, 1951) 



