MINERAL NUTRITION 155 



Heifers Non-Mineral Group 



Weight on 

 July 1, 1928 

 88 685 1135 +450 



99 570 1140 +570 



Total gain .... .... +1020 



Mineral Group 



98 575 1130 +555 



100 445 855 +410 



Total gain +965 



The final weight of No. 42 was taken in October, 1927. No later weight is available as the 

 cow was in isolation stall. 



No. 88 was in a somewhat earlier stage of gestation than the other three heifers. 



The presence of one Jersey in each age class (No. 43 in the young cow class, No. 

 100 in the heifer class) complicates analysis of these weight data somewhat. A 

 truer picture of the case is obtained if the growth increments are presented on a 

 percentage basis (see Table 4). 



Table 4. — -Percentage Increase in Weight of Young Cows and Heifers 



Cow No. Mineral group Non-mineral group 



33 11.5 



40 8.9 



71 40.8 



35 11.1 



42 7.1 



43 2.4 



Average 19.9 7.0 



Heifer No. 



98 96.5 



100 92.1 



88 65.7 



99 100.0 



Average 94.6 81-3 



At first glance this looks like a considerable difference in favor of the "mineral" 

 group, but it is discounted by the fact that they average six months younger in 

 the case of the young cows and two months younger in the case of the heifers than 

 the "non-mineral" group. Unfortunately the weights of the groups at identical 

 ages are not comparable due to considerable differences in stage of gestation. 

 If Nos. 43 and 71 be dropped out of the young cow group the others are of identical 

 age, and the difference is seen to be very small, 8.75 percent increase in the "non- 



