128 



to make a pound of increase 3.6 pounds of dry matter in the 

 grain ration and 6 pounds of dry matter in the sweet potato 

 ration. 



This 'result, so disadvantageous to sweet potatoes, was 

 probably due in part to the fact that the pigs would not eat a 

 sufficient quantity of the bulky ration to obtain the same 

 amount of dry matter as was furnished by full rations of the 

 more concentrated mixture. 



By feeding a ration made up of equal weights of sweet 

 potatoes and cowpeas, the daily consumption of nutritive 

 materials would doubtless be increased, and on such a ration 

 we might expect results more favorable to sweet potatoes. 

 Again, hogs rooting in potato fields might eat larger quanti- 

 ties of sweet potatoes. 



But the difference is apparently too wide to be ascribed 

 wholly to the ampunt of food eaten. The figures suggest that 

 the dry matter of sweet potatoes is inferior in composition or 

 in digestibility to that of corn. 



The results show that under the conditions of this experi- 

 ment one pound of corn was worth much more than three 

 pounds of sweet potatoes. These figures do not enable us to 

 place an exact value on potatoes, but indicate that pricing 

 corn at 40 cents per bushel, sweet potatoes were worth less 

 than 13 cents per bushel of 56 pounds. (The legal weight 

 of a bushel of sweet potatoes varies in different states.) 



If corn were worth 50 cents per bushel, these results 

 would give to sweet potatoes a value considerably below 17 

 cents. Probably 10 and 12 cents per bushel would be a closer 

 estimate of the nutritive value of a bushel of potatoes fed 

 with cowpeas in the proportions employed in this experiment. 



It is plain that sweet potatoes could not profitably be 

 grown, stored, and fed to hogs, even if each bushel could be 

 converted into pork worth 10 to 15 cents. This does not 

 imply that sweet potatoes cannot be profitably employed as 

 food for hogs. But a profit is possible only by saving the 

 expense of harvesting, the heaviest single item of expense in 

 sweet potato culture. If the hogs do the rooting, the sweet 

 potato is doubtless a cheaper food than corn on some sandy 



