REPORT OF THE CHEMIST. 167 



SESSIONAL PAPER No. 16 



Fat. — Of the non-nitrogenous constituents, fat has the highest nutritive value; 

 and this chiefly because it contains a larger percentage of carbon than fibre, or the car- 

 bohydrates, in the burning of which in the blood much heat is evolved. By its combus- 

 tion, fat generates the greater part of the heat of the body. Its high value is 

 largely due, also, to the fact that it can be transformed into fatty tissue of the 

 animal much more readily than the other organic ingredients. It aids the digestion 

 and assimilation of the albuminoids and preserves them from undue waste. 



Fibre — Is the least valuable of the food ingredients. It is the part of plants that 

 in part corresponds in function to that of the bones of animals, viz., the supporting 

 and strengthening of the other tissues. By chemical means it can be separated from the 

 other parts of a fodder as a fibrous or woody material. As plants mature, the fibre, as 

 a rule, becomes less digestible, chiefly owing to the deposition of ligneous or woody 

 matter. In composition and function, fibre is similar to the ' Nitrogen-free extract.' 



Nitrogen-free Extract or Carbo-hydrates. — Under these terms are included 

 starch, sugars and many allied substances forming, usually, the larger part of the dry 

 matter of a fodder. Their function in the animal economy is to produce heat and 

 energy, though under certain circumstances they may become a source of fat. 



Protein or Albuminoids. — These substances constitute the nitrogenous portion of 

 tlie fodder. They are certainly the most important and most valuable of all the nutri- 

 tive ingredients, for in the animal economy they alone can play the part of flesh pro- 

 ducers, entering into the composition of muscle and cartilage and bone and furnish- 

 ing essential constituents for the vital fluids — blood and milk. They may also serve in 

 the production of fat, and in the development of heat and energy. 



Ash or Mineral Matter — Is that part left when a fodder in the course of analysis is 

 burned, an operation that destroys and dissipates the organic matter. It is composed 

 chiefly of lime, magnesia, potash and soda, combined with phosphoric, hydrochloric and 

 silicic acids. The functions of these materials in the animal are to assist in the 

 formation of bone (largely composed of phosphate of lime) and to furnish that small 

 quantity o£ mineral matter found in all animal tissues. It also replaces those saline 

 substances daily excreted. 



THE CHEMISTRY OF RAPE. 



During the past few years the growing of rape — a plant which, as far as Canada is 

 concerned, may be considered a newly introduced fodder — has been receiving 

 increased attention from our farmers. In certain districts it is now largely used as a 

 forage crop for sheep, swine and steers, and undoubtedly still larger areas in the 

 future will be sown for this purpose. It seemed desirable, therefore, that we should 

 determine by analysis the food value of tl»s plant, so that its true position as 

 regards other coarse or forage crops could be arrived at, and, further, that we should 

 ascertain what changes in its composition affecting its nutritive value take place as 

 it advances towards maturity. 



To this end, samples were collected from the rape crops on the Central Farm 

 during the past season at several stages of the plant's growth and submitted to 

 analysis. The variety grown was Dwarf Essex, and the seed was sown at the rate of 

 4 pounds per acre in drills 30 inches apart. The data are given in tabular form to 

 facilitate comparison of the composition of the plant at different stages. In addition 

 to analyses of the whole plant, an examination was made of the stalks and foliage, 

 separately, of the somewhat mature rape plant. 



