TANKAGE AS A SOURCE OF PROTEIN FOR DAIRY COWS 



By J. G. Archibald, Assistant Research Professor of Animal Husbandry 1 



INTRODUCTION 



Tankage, a common article in the feed and fertilizer market, is a by-product 

 of the meat packing industry, and consists of a mixture of meat scraps, trimmings, 

 and bones, the residue from the preparation of the standard market cuts of meat. 

 It is cooked at high temperatures to sterilize it and to render out most of the fat, 

 and is then dried and ground. The final product is a fine, quite dry meal varying 

 in color from light to dark brown and with a characteristic though not objection- 

 able odor. It is composed almost entirely of protein, calcium (lime), and phos- 

 phorus. The source of the last two mentioned is bone, and since the proportions 

 of meat and bone vary, there are several grades of tankage with varying per- 

 centages of protein, lime and phosphorus. Tankage is generally sold on the basis 

 of its protein content and the grades vary from 45 percent protein or less, which 

 is usually known as "meat and bone", to 60 percent protein, which is sometimes 

 referred to as "meat meal". 



The better grades of tankage have been fed to hogs and poultry for years and 

 to beef cattle to some extent more recently. It is only very recently, however, 

 that it has been thought of as a possible source of protein for dairy cows. At 

 present there is a relative scarcity of protein supplements of plant origin due 

 largely to the drouth of 1934, while at the same time tankage is plentiful and its 

 price per unit of protein is rather attractive. Furthermore, certain investigations 

 have demonstrated an apparent superiority of animal proteins over plant pro- 

 teins for nutritive purposes. 



In view of these facts it was decided to conduct at this station an investigation 

 of the value of tankage for milk production. This was done during the winter 

 of 1934-35, the feeding trial lasting somewhat over five months, from November 

 19 to April 27. 



METHOD OF CONDUCTING THE INVESTIGATION 



Twenty-four cows were chosen from the State College herd and divided into 

 two groups of twelve each, as similar as possible with respect to breed, age, live 

 weight, stage of lactation, amount of milk being produced and fat test of the 

 milk. Table 1 shows that the groups were quite similar in all respects. 

 Jh'The tankage used in the experiment was a high-grade, dry-rendered product. 

 It was compared with a mixture of soybean meal and cottonseed meal. The 

 groups of cows were fed by the double reversal method, one group receiving the 

 tankage ration for forty days while the other received the soybean-cottonseed 

 ration. At the end of that time the rations were reversed, the group which had 

 been receiving tankage being changed to the soybean-cottonseed ration and 



'The author desires to make the following acknowledgements: To Wilson & Co., Chicago, who 

 supplied the tankage used in the feeding trial; to C. H. Parsons, farm superintendent at Massachu- 

 setts State College, for intelligent and effective cooperation throughout the course of the experi- 

 ment; and to Thomas Muir, herdsman, who had immediate charge of the animals, and whose 

 attention to detail and interest in the work contributed to its success. 



