244 REPORT ON NUTRITIVE VALUE OF CERTAIN AUSTRALIAN GRASSES, 



Carbohydrates, so far, have been determined, as is usually the case, by 

 difference. This method, however, is far from satisfactory, and the writer hojies 

 to be able to estimate them in more detail at a later stage in the work. 



V. Experimental. 



As before mentioned, the e.\periments described in tliis iiaper have been 

 carried out on the air-dried material. Agricultural chemists generally 

 have found that, after allowing for the moisture content, there is 

 no great difference between the chemical constitution of the green 

 and the air-dried material of feeding stuffs (Brunnich and Smith, 1907). 

 Honcamp (1915) carried out numbers of experiments with both, and he con- 

 siders that, if the material is dried in vacuo, there is absolutely no difference in 

 the nutritive value. The analysis of the air-dried material may, perhaps, also 

 be considered the more reliable of the two. The results of the analyses of 

 grasses from various parts of the State are shown in Table I. With regard 

 to the meaning of the terms "crude" protein and "true" protein used in the 

 tables, "crude" protein represents the total nitrogen, as determined by the 

 Kjeldahl Gunning Arnold method before mentioned, multiplied by the factor 

 6.25. The use of this factor has been subjected to a good deal of criticism in 

 America and elsewhere, but American chemists have not, so far, succeeded in 

 finding any other factor which would give more accurate results in tlie case 

 of grasses. G. L. Bidwell (1916) writing on this subject, states that, although 

 in the case of wheat and other substances containing a few well known proteins 

 a factor giving better results may be easy to obtain, it is a different matter in 

 the case of substances in which the protein content is of a complex character. 

 He says "consider the labour involved in determining the factor to apply to any 

 one substance. It would be necessarj' to determine the amount of each pi'otein 

 in that substance then to prepare it in a pure condition so that the percentage 

 of nitrogen might be determined therein. This is a problem for the specialist who 

 has available almost unlimited time and money" (p. 29). He recommends the 

 retention of the factor 6.25 in such cases, and it has therefore been made use 

 of in the preliminary stages of this work. 



The term "true" protein is used to designate the precipitate obtained by 

 Stutzer's Reagent. This precipitate is Kjeldahled as in the case of the crude 

 protein, and the result so obtained is multiplied, as before, by the factor 6.25 

 (Assoen. Offic. Agric. Chemists, 1920). The albuminoid ratio mentioned in the 

 tables is "the ratio of non-nitrogenous to nitrogenous nutrients in any food" 

 (Murray, 1914, p. 325). In order to determine this ratio, the non-nitrogenous 

 nutrients must all be expressed in the terms of one of them — carbohydrates. 

 The amount of ether extract must, therefore, be multiplied by a factor which 

 represents the value of fat as compared with carbohydrates. The factor com- 

 monly used is 2.3 (Murray, 1914). 



vi. Disetis-fion of Tables. 



Effect of Soil and Climate on the Chemical Constitution of Grasses. 



A good deal of work in this connection lias been carried out in the United 

 States (Le Clerc and Voder, 1914), notably in Wyoming (Knight, etc., 1908, 

 1911), where it wa.s found that the percentage of nitrogen appeared to increase 

 with the increase in altitude, while the percentage of crude fibre, under the 



