650 FEEDS AND FEEDING 



by its use. (270) Commonly the terms * ' tankage ' ' and ' * meat meal ' ' are 

 used for the same product. 



The results of trials in which well-proportioned rations of corn and 

 tankage have been compared with corn alone for pigs not on pasture, have 

 been given on previous pages. (938) It is there pointed out that on 

 corn alone young pigs failed to make even fair gains, and that com- 

 pared with this inefficient ration, 100 Ibs. of tankage is worth more than 

 600 Ibs. of corn. Well-grown pigs which were started on corn alone 

 at an average weight of 150 Ibs. stood this poor ration somewhat better, 

 but even for feeding such older pigs, each 100 Ibs. of tankage saved 505 

 Ibs. of corn. These figures can not be taken as showing the actual money 

 values of tankage, for several protein-rich supplements are usually avail- 

 able for swine feeding, and the actual feeding value of tankage will 

 depend on the prices of the other supplements available. 



.Experiment station scientists have usually been able to secure tankage 

 of high grade more readily than they could obtain a constant supply of 

 skim milk or buttermilk. Hence they have quite commonly used tankage 

 as a standard with which to compare other protein-rich supplements for 

 swine. Accordingly, in this chapter the values of skim milk, wheat mid- 

 dlings, linseed meal, and several other supplements are compared directly 

 with that of tankage. (958-61, 969, 973) 



The best grades of tankage, which are often called * ' digester tankage, ' ' 

 usually contain about 60 per ct. of crude protein and 6 to 10 per ct. of 

 fat, thus furnishing nearly twice as much protein as linseed meal. High 

 grade tankage produced by the large companies usually meets in com- 

 position the guarantees of the makers, and it is commonly in good 

 mechanical condition, being dry and finely ground. 



The lower grades of feeding tankage contain less crude protein, and 

 usually carry more fat. Such products usually range in protein content 

 from 40 to 50 per ct. Often such feeding tankage is produced at plants 

 which render animals that have died from one cause or another. If 

 care is taken at the plant to keep the finished tankage away from the in- 

 coming dead animals, which may be diseased, there should be no danger 

 in feeding such tankage. Some of the smaller plants are not equipped 

 with suitable drying and grinding apparatus and therefore the tankage 

 they produce is suitable only for fertilizer. Little work has been done to 

 determine the relative value of the various grades of tankage. 83 Common- 

 ly the protein content will furnish an approximate measure of the value 

 per ton of various grades, tho some allowance should be made for the 

 other ingredients. For example, a well-made tankage which contains only 

 about 40 per ct. of crude protein and 12 per ct. fat will be worth slightly 

 more than two-thirds as much as digester tankage containing 60 per ct. 

 crude protein and only 6 per ct. fat, due to the higher fat content of the 

 low-grade tankage. Such tankage also contains more bone than digester 

 tankage, but digester tankage usually contains sufficient so that there 



83 Evvard, Iowa Rpt. 1918, pp. 19-20. 



