664 EXPERIMENT STATION RECORD. 



considerations are advanced, wbicli bear particularly upon the relation between 

 protein supply and muscle mass. The protein which is lost from the body 

 immediately after the stored protein, in a case of transition from a protein- 

 rich diet to a nitrogen-minimum is designated " protein of transition " ( iJher- 

 ganffseiweiss) . The loss of such protein is not to be regarded as harmful to 

 the cell condition of the body. 



Concerning protein gains, M. RuBNEaj {Arch. Anat. u. Physiol., Physiol. Abi., 

 1911, No. 1-2, pp. 67-84; a&s. in Chcm. Zetitbl., 1911, II, No. 9, p. 626).— Con- 

 tinuing the above studies, the author considers the physiological function of 

 that part of the nitrogen of the food which remains in the body. The protein 

 which serves for the reconstruction of the cells to their optimum protein con- 

 dition is designated as " repair protein " or " amelioration protein." It is 

 not possible to continue the storing up of " repair " protein after the maximum 

 nitrogen condition has been reached. 



Metabolism in extreme age, R. Uhlmann (Beitrag sum Stoffwechsel im 

 Greiseiihalter. Inaug. Diss., Munich, 1911, p. 13; ahs. in ZentU. Blochem. u. 

 Biophys., 12 {1911), No. 11, p. ^16). — Metabolism is greatly decreased in old 

 age. In many cases an essential factor in this decrease is the poor utilization 

 of the food. 



ANIMAL PRODUCTION. 



The maintenance rations of farm animals, H. P. Aemsby (Z7. Si. Dept. Agr., 

 Bur. Aniin. Indus. Bui. I.'/S, pp. HO, fig. 1). — A summary and a critical d.is^• 

 cussion of investigations on the maintenance requirements of the principal 

 farm animals, which, in its technical sense, means the minimum required simply 

 to sustain life when doing no work and yielding no material product, in dis- 

 tinction from the popular definition which signifies the total amount of feed 

 required for the animal to perform its daily work, or, in the case of young 

 animals, to make normal growth. The fasting katabolism, material katab- 

 olized, ratio of protein to -total katabolism, influence of body fat, relative con- 

 stancy of energy katabolism, and the factors affecting the energy requirement 

 for daily maintenance are discussed. 



Averaging the results of the main requirements of cattle, which have been 

 studied more extensively than those of other species, it appears that thin 

 cattle require about 10.5 therms, and fat cattle 15.05 therms of metabolizable 

 energy per 1,000 lbs. live weight, or, exiH-essed in terms of available energy, 

 6.31 and 8.83 therms, respectively. This available energy is not necessarily 

 identical with the energy values in terms of which the values of feeding stuffs 

 and requirements of animals have been expressed by Kellner and others, since 

 Kellner's results were obtained by comparison of productive rations. From 

 the available records, however, the two are probably about the same in the 

 case of concentrated feeds, but the available energy of coarse feeds below 

 maintenance may be greater than their productive values above the point of 

 maintenance. If this should prove to be the case, the estimated requirement 

 of 6 therms of Kellner's production values will give a maintenance ration ample 

 for practical purix)ses, but w^hich will be a somewhat too large deduction to 

 make in estimating the productive part of the ration. 



In discussing the minimum of protein, the author concludes that on a diet 

 containing an abundance of carbohydrates a supply of protein equivalent to 

 the fasting protein katabolism is sufficient to meet the needs of the organism, 

 while it is possible that a less amount will suffice. Fats appeared to be dis- 

 tinctly less efficient than carbohydrates in keeping the protein katabolism at 

 the minimum. From data obtained it is estimated that 0.6 lb. of crude protein, 



