CONVERSION OF FEEDING STUFFS 31 



greater (bran, meal, oil cake, etc.). It is best, therefore, to make use of 

 the fermentation process just described, for the roughages only, and to 

 feed the concentrates separately or mix them with the fermented rough- 

 ages immediately before feeding. 



This character of feed is suitable for the coarser breeds of cattle and 

 sheep, less so for young stock and horses, and for swine only when it is 

 composed of root crops and, at most, minimal quantities of finely cut 

 roughage. 



7. Conversion. This chemical term is used to designate a process by 

 means of which woody feeding stuffs (straw, sawdust) are converted into 

 digestible substances. The microscopical incrustations of the nutrient 

 ingredients, which prevent digestion, are removed by this process. A cer- 

 tain degree of conversion occurs in the ordinary process of fermentation. 

 To convert straw more completely, more effective means are necessary, 

 above all, treatment with strong bases (lye and unslaked lime). 



It is to Kellner that we owe our knowledge of the scientific principle 

 underlying the conversion of straw. Lehmann, of Goettingen, however, 

 applied the principle in a broad and practical manner in his work which 

 covered a period of more than twenty years. But it was the pressing 

 necessity of the late World War that led to its general adoption. Oex- 

 mann deserves the credit for having first directed attention to a method 

 for ultilizing the straw pulp of paper mills as a feeding stuff. This pulp 

 is treated with mollasses (straw concentrate II), followed by treatment 

 with yeast or gluten concentrate (albuminous straw concentrate I). 



Colsman invented a process of converting straw that could be conducted 

 at home, on the farm.. The straw is cooked in 8 per cent sodium lye, in 

 open kettles set in masonry. The superfluous water is then expressed. 

 After being washed to remove the excess lye, the matrial is ready for 

 feeding. 



Beckman demonstrated that conversion is possible and practicable 

 without the use of heat and that the lye solution can be used a second and 

 a third time providing it is reinforced to the extent of the used fraction. 

 This simplifies the process and reduces the expense materially. An addi- 

 tional advantage for the Beckman process is that many of the nutrients 

 that are destroyed by heat are retained. The available product is in- 

 creased in this manner from 55 or 58 per cent to 75 or 80 per cent. The 

 digestibility of straw concentrate is about 70 to 75 per cent as compared 

 with 35 per cent of the untreated or unconverted straw. 



Milk of lime exercises a converting effect upon straw similar to that 

 of sodium lye. The solution of the silicic acid and the lignins (to the 

 presence of which the indigestibility of straw is due) is less complete, 

 however, while the desired destructive action of cellulose and of the 

 pentosanes is the same as that of sodium lye. Thus the food value of 

 straw treated with lime is less than that of the same material treated with 

 sodium lye. The action of soda (sodium carbonate) is similar to that of 

 lime. 



