178 Journal of Agricultural Research voi. x,no. 4 



15 minutes. One of them became blind. The critical factors in this 

 ration were poor mineral content and toxicity. This statement is based 

 on the records made by other animals of this species (to be described 

 later in this paper) and on records with rats and swine (5, 12). 



Plates 18 to 22 illustrate the condition of all lots as calves and at the 

 end of two years' feeding. 



In contrast to the all-wheat-ration group stood the all-com-ration 

 group. The latter not only showed continuous growth, but became 

 physiologically active and produced strong calves. The decline in weight 

 at the end of two years shown by No. 575 was due to slow recovery after 

 calving. 



When the ration consisted of wheat grain and corn stover, fair but 

 sustained growth was obtained; but it was below normal. The marked 

 improvement made by the use of another roughage, contributing at 

 least as one factor a better mineral content, was most illuminating. 

 These animals showed oestrus and were bred. 



When the ration was made from com grain and wheat straw, slow 

 growth continued for a long time, but the animals were in poor condi- 

 tion. They were better than the wheat-grain and wheat-straw group, 

 since we were able to get one bred, although the other failed to show 

 oestrus. As will be more fully demonstrated later, the critical factor 

 was the mineral content of this ration, and these results serve to empha- 

 size how important a factor the mineral side of a ration becomes in 

 reproduction. 



Strong and vigorous individuals resulted where a corn-grain plus 

 wheat-straw plus alfalfa mixture was used. The displacement of half 

 of the wheat straw with alfalfa hay changed the ration from a failure to 

 a success. It might be assumed that the introduction of alfalfa hay 

 corrected the ration by the addition of more or different proteins, but 

 it is more probable that its chief but not only contributing factor in 

 this case was a more efficient ash mixture. 



In Table II are recorded the reproduction records of these animals, 

 as well as those of five older cows, reserved from our older herd, the 

 records of which were made public by the writers (6) in 191 1. The con- 

 stituents of the ration fed the older cows were in the same proportions 

 as used for the younger heifers, as shown in Table I. For breeding these 

 animals a Guernsey bull was used in the case of all the old individuals, 

 but a Holstein bull served the 10 Holstein heifers. In addition to the 

 records of birth, there is given in the last column the average daily 

 weight of milk produced for 30 days. 



