134 THE SCIENTIFIC FEEDING OF ANIMALS 



I. CHEMICAL EXAMINATION 



A. Determination of Albumen, Fat, Nitrogen-Free Extract, Crude Fiber, 



Mineral Matter or Ash and Water 



See page 3, etc. 



B. Determination of Sand, Lime, Infusorial Earth, Barite and Other Minerals 



Sand, gypsum, barite and other minerals admixed with feeding stuffs may be 

 injurious to the health of animals. The following methods are employed for their 

 detection. 



Chloroform test. — Agitate 5 to 10 grams of the feeding stuff with chloroform. 

 The feeding stuff material will float and the sand, etc., sink to the bottom of the 

 flask. Separation and quantitative determination follows. 



Carbonic acid test. — The feeding stuff is washed off with water or chloroform, 

 as indicated above, and the residue treated with dilute mineral acid. The presence 

 of lime is indicated by effervescence (carbonic acid gas). 



Ash analysis (see p. 4). — The determined ash content is compared with that of 

 the unadulterated feeding stuff. To determine the amount of sand in the ash the 

 latter is treated with dilute hydrochloric acid and the residue boiled in a 5 percent 

 solution of bicarbonate of soda. The residue consists of sand, clay (earth) and a 

 part of the un-dissolved silicic acid present in the glumes or chaff. 



The permissible sand content in feeding stuffs is 0.2 to 0.3 percent. 



C. Determination of Com Cockle, Ergot, etc., in Meals 

 by Means of Vogl's Reagent. 



To 2 grams of meal, placed in a test tube, add 10 c.c. of 70 percent alcohol con- 

 taining 5 percent of hydrochloric acid ; agitate thoroughly, heat slightly and allow 

 to settle. 



If the fluid remains colorless — Wheat and rye. 



If the fluid becomes yellowish — Ryg (sometimes), corn, barley, oats, peas. 



If the fluid becomes orange — (Rye, barley, corn), rice, millet, corn, cockle, bearded 

 darnel. 



If the fluid becomes red — (Rye, barley, corn, rice, millet) vetches, ergot. 



If the fluid becomes bluish green to green — Cow wheat and yellow rattle (Hart- 

 mann ) . 



Seed skins (bran) of green rye produce a red color; skins of yellow rye grains, 

 a pale ocher yellow ; both together produce an orange color. The seed skins of 

 wheat do not give this reaction; those of barley as a rule also fail to give it. Vogl's 

 reaction is not applicable to rye bran. 



Vogl's reaction is therefore ambiguous. It serves mainly as a guide and to as- 

 sist in finding suspicious material. To complete the latter process the slightly 

 warmed solution or mixture is poured on a piece of blotting paper and the stained 

 particles picked out for microscopic examination. 



Ergot stains the solution red. The addition of ether and a few drops of sul- 

 phuric acid changes this to violet. If the red color is due to vetches, the addition 

 of the latter reagents produces a greenish yellow precipitate. 



The detection of corn cockle with Vogl's reaction is assisted by previous moisten- 

 ing of the meal in question with concentrated hydrochloric acid (intensified reaction). 

 The presence of 0.8 percent of corn cockle meal (with hulls of cockle) may be de- 

 tected by this method. Microscopical examination gives more definite results (pp. 

 140-145). 



D. lodin-Starch Reaction 



Certain by-products of oil production contain mere traces of starch (linseed cake 

 and meal). Cottonseed by-products contain no starch whatever. On the other 

 hand the seeds of weeds that are frequently used to adulterate oil by-products usually 

 contain more or less starch. 



The presence of starch is detected as follows: One gram of the suspected meal 

 is boiled in about 10 c.c. of water, allowed to cool, and treated with a few drops 

 of Lugol's solution (1:10:300) (iodin, potassium iodid 10, water 200). A result- 

 ing blue or blackish blue color indicates the presence of starch (see p. 137). 

 E. Testing Spoiled Feeding Stuffs 



Spoiled meals have an unpleasant musty or moldy odor. Heating in water or 

 potash solution intensifies the odor. Gawalowsky's test is the most reliable. Mix 

 1 gram of the suspected meal with 4 to 5 c.c. of potash solution in a wide test tube. 



