80 GROWTH 



placed on a low calcium ration, containing as a source of rough- 

 age, corn, corn silage or corn stover, and timothy hay. Corn and 

 gluten meal were fed as concentrates. The ration to supply 

 larger quantities of calcium contained alfalfa hay and a concen- 

 trate made up of a mixture of corn, wheat bran, and cottonseed 

 meal. The heifer which received the liberal quantity of calcium 

 remained normal in health and vitality and grew at the nor- 

 mal rate. The one receiving the ration deficient in calcium, how- 

 ever, did not fare quite so well. For the first thirteen months 

 she seemed to be quite normal, but then became stiff in the 

 joints and developed an abnormal gait. Finally her knees were 

 partially bent and after lying down she found it very difficult 

 to rise again. The ration was then changed and the heifer be- 

 came nearly normal in condition within a month. 



More recent data (unpublished) obtained at this station, with 

 swine, emphasize the great capacity of animals to adjust them- 

 selves to unfavorable dietary conditions as exemplified by a ra- 

 tion deficient in calcium. Female pigs, aged about sixteen weeks, 

 were placed on a diet as low in calcium as it is practically pos- 

 sible to prepare. Analyses indicated that the ration contained 

 less than 0.05 per cent of that element. If the pigs had been 

 placed on this ration at eight weeks of age, we feel quite certain 

 that the trial would have ended in disaster. These animals grew 

 very well, however, though two sows suffered broken legs, and 

 on post-mortem examination were found to have exceedingly 

 soft, spongy bones. The others farrowed the following spring, 

 but none were able to rear their young. One litter was very weak 

 at birth, presumably because of the poor state of nutrition of the 

 mother. 



The importance and physiological role of iron has been em- 

 phasized for years. One of the recent reports, 16 of observations 

 made on a practical swine-breeding experiment, again empha- 

 sizes the importance of iron for growing animals. The sows 

 were left on pasture until two weeks of farrowing time, after 

 which they were confined to pens and fed a ration of fishmeal, 



