372 EXPERIMENT STATION EECORD. [Vol.43 



for the computations, altlioufih those investigators tiiemselves refused to use 

 their ox and sheep data directly for such a puipose on the ground that the 

 par(icuhir lean and fat animals analyzed were not comparable. 



31eat production, .1. A. Mukkay {Jour. Ayr. Sci. [JJnylund], 9 {1010), No. 2, 

 pp. 17Jf-181, fly. 1). — The author summarizes the views developed in the paper 

 noted above, and proposes that basal katabolisni be computed on the basis of 

 tlie fat-free body weight. 



" It has been demonstrated tliat basal katabolism does not vary as the live 

 weight or as tlie two-thirds power of the same when the variation in the latter 

 is wliolly or mainly due to alteration of condititm; that it varies approximately 

 as tlie two-thirds power of tlie live weight for animals in lil^e condition is gen- 

 erally accepted. The basal katabolism in fat-free condition, therefore, sug- 

 gests itself as the natural fundamental unit for estimation of maintenance 

 requirements." Any determiuatiou of basal katabolism (B) derived from 

 actual measurement is supposed to be related to the basal katabolism (&) of the 

 same animal in fat-free condition by the foi-mula 



6= (1—1.247 f)B 



where 100/ is the percentage of fat in the body as estimated from the condition 

 of the living animal at the time of the determination. The constant 1.247, 

 whicli is considered of general application to ruminants, was derived by assum- 

 ing tliat tlie steer studied by Armsby and Fries (E. S. R., 38, p. 469) contained 

 20 per cent fat when in a medium condition and 35 per cent after fattening. 

 On the further assumption that determinations of the fat-free basal katabolism 

 of any two animals are to eacli other as the two-thii-ds powers of their fat-free 

 body weiglits (no geometrical interpretation offered), it is found that the 

 maintenance requirement of a very fat animal is much greater than that com- 

 puted from the total live weight. 



The nutritive value of feeding stuffs, J. A. Mueeay {Sci. Prog. [London], 

 14 (1010), No. 54, pp. 319-326, figs. 2). — The author discusses the various ac- 

 cepted metliods of comparing the nutritive values of feeds, notes that the main- 

 tenance starch equivalent of "Wood and Hainan (E. S. R., 41, p. 270) " is, in 

 effect the discredited ' total digestible nutrients,' and not starch equivalent at 

 all," declares in favor of energy values, summarizes his theory of basal kata- 

 bolism (see preceding abstract), and suggests a geometrical method of com- 

 paring feeding stuffs in which the ratios of net energy to total (gross) energy 

 and of nonavailable metabolizable energy to total energy are considered tangents 

 of angles, the former being termed tlie productive index. 



Net energy values and starch values, H. P. Armsby and J. A. Fries {Jour. 

 Agr. Set. [England], 9 {1919), No. 2, pp. 182-187) .—This paper was written to 

 remove misapprehensions as to the relationships between starch values, carbo- 

 hydrate equivalents ("total" nutrients), metabolizable energy, and net energy. 



" Kellner's starch values represent neither the digestible carbohydrates 

 (actual or potential) contained in feeding stuffs nor the fuel value of the 

 material which they supply to the tissues. What they seek to express in 

 another form is precisely what we have expressed in our net energy values, viz, 

 tlie extent to which the feed is able either to diminish or prevent loss of stored 

 energy from the body (submaintenance and maintenance rations) or to bring 

 about a storage of energy in new tissue (fattening, growth, etc.). Aside from 

 experimental errors, there is no difference in principle between the two sets of 

 Aalues but merely a difference in the manner of expression." The attempt to 

 express energy in terms of matter is considered " an unfortunate and an un- 

 necessary concession to established usage." 



