154 Feeds and Feeding. 



stock interests of this country, especially of the South. To the dis- 

 credit of our live-stock interests, one billion pounds of cotton-seed 

 cake are annually exported to other countries. (574) 



196. Flax seed.— In 1909 about 25,767,000 bushels, each of 56 lbs., 

 of seed from the Hax plant, Limmi usitatissimum, were produced in 

 the United States.^ The reserve building material is stored in the 

 flax seed largely as oil and pentosans, instead of as starch, which 

 most seeds carry, no starch grains being found in well-matured 

 flax seeds. On account of the high commercial value of the oil it 

 contains, flax seed is rarely used for feeding stock other than 

 calves. (574) 



The oil of the flax seed is either extracted by the old process, 

 thru pressure, as in the production of cotton-seed oil, or it is dis- 

 solved out of the crushed seed with naphtha, the residue in either 

 case being called linseed oil meal. In the United States nearly all 

 the linseed oil meal is made by the old process. 



According to WolP in the manufacture of new-process oil meal 

 the crushed and heated seed is placed in large cylinders or perco- 

 lators, and naphtha poured over the mass. On draining out at the 

 bottom the naphtha carries with it the dissolved oil. After re- 

 peated extractions steam is let into the percolator, and the naphtha 

 remaining is completely driven ofi" as vapor, leaving no odor of 

 naphtha on the residue, which is known as "new-process" linseed 

 oil meal. 



197. The swelling test. — WolP gives the following method of as- 

 certaining whether oil meal is new- or old-process: "Pulverize a 

 small quantity of the meal and put a level tablespoonful of it into 

 a tumbler; then add 10 tablespoonfuls of boiling hot water to the 

 meal, stir thoroly, and leave to settle. If the meal is new-process 

 meal, it will settle in the course of an hour and will leave half of 

 the water clear on top." Old-process meal will remain jelly-like. 



198. Old- and new-process oil meal.^ — By artificial digestion trials 

 with old- and new-process oil meal WolP found that 94 per ct. of 

 the crude protein in the old-process and 84 per ct. of that in the 

 new-process oil meal was digestible. The lower digestibility of the 

 new-process meal is doubtless due to the use of steam for driving 

 off the naphtha, since cooking lowers the digestibility of many crude 

 protein-rich foods. Despite its somewhat lower factor of digestibil- 

 ity, new-process oil meal contains rather more digestible crude pro- 



^ IT. S. Dept. Agr. Yearbook, 1909. ' Loc. cit. 



= Kpt. Wis. Expt. Sta., 1895. ■* Loc. cit. 



