DEVELOPMENT 265 



are known to be deficient in calcium. This is particu- 

 larly true when, as in the case of swine, the rations are 

 chiefly composed of grain with a relatively small propor- 

 tion of roughage. It is a popular notion that feeding 

 pregnant farm animals a high calcium ration will cause 

 the skeletal system of the foetus to develop even beyond 

 what may be regarded as normal. As a result of this 

 greater development of the skeleton, it has been alleged 

 that the mother may sometimes have serious difficulty 

 in expelling the foetus. Sbme confirmation of this belief 

 is apparently found in the work of Evvard already de- 

 scribed. But in this investigator's trials a ration abnor- 

 mally deficient in calcium and protein is compared with 

 normal rations. Adding an excess of calcium to a normal 

 ration may not necessarily increase the size or change the 

 composition of the foetus. In this respect we know that 

 similar changes in the ration do not change the composi- 

 tion of the milk. At the Wisconsin Experiment Station, l 

 Hart, Steenbock and Fuller compared normal rations 

 with a high calcium ration fed to pregnant swine. Eight 

 Poland China sows were fed in lots of two each. Three 

 lots were fed on a high calcium ration by the addition of 

 calcium carbonate, calcium phosphate (floats) and alfalfa. 

 One lot was fed a normal standard ration known to be 

 adequate for pregnant swine. These rations were fed 

 throughout the gestation period. Although the calcium 

 rations contained five times the amount of this mineral 

 present in the normal ration, there was no evidence 

 that the skeleton of the foetus was influenced in 

 any degree. The authors in summarizing their results 



1 Hart, Steenbock and Fuller, " Calcium and Phosphorus 

 Supply of Farm Feeds and their Relation to the Animal's Re- 

 quirements," Wisconsin Research Bulletin No. 30. 



