JiL'POh'T OF THE CHEMIST. 169 



SESSIONAL PAPER No. 16 ' 



It is very evident from the large percentage of water present throughout the 

 whole life of the plant that rape is to be classed as a succulent forage crop. For this 

 I'eason (its high water content) it cannot be preserved in the silo, nor, on account of 

 the crumbling to powder of its leaves on drying, can it be cured on the field. It is, 

 therefore, consumed, either on the field or by soiling, by the animals as it grows, and 

 thus all expense in harvesting saved. * 



Dry Matter. — Though the variation in the composition of the plant throughout its 

 period of growth is not great, there is a well marked tendency in certain directions that 

 we may call attention to. In the first place, it is to be noted that while there is not 

 much change as regards water content during the earlier two months of growth, there 

 is from that period on a gradual increase in the percentage of dry matter. Thus, in 

 rape one month old we found G -80 per cent dry matter, while in that three months old 

 (when the whole plant was still edible), there was 10 'll per cent dry matter. It is 

 apparent, therefore, that, judged from this consideration solely, the older plants, weight 

 for weight, would have the greater fodder value. This increase in the amount of dry 

 matter seems to be due principally to the larger proportion of stalk to foliage in. the 

 more mature rape. Thus, in N"os. 6 and 7 we have the composition in detail of the 

 stalks and foliage re-pectively of plants of the same age as those recorded under No. 5. 

 These show that the stalks contain approximately 5 '5 per cent more dry matter than the 

 foliage. After the plants have reached a certain and more advanced stage of growth 

 this apparent benefit is, however, to some extent offset by the greater development of 

 fibre in the stalks, making them hard and unpalatable, and to some degree no doubt 

 le-s digestible. The foliage always contains much less fibre than the stalks. 



The changes that take place in the composition of the dry matter during the 

 period of growth are best understood from a study of the data recorded for the water- 

 free substance. 



Fat. — Usually a number of substances, of which chlorophyll is the chief, are 

 included with the fat when employing the ordinary process employed for fat estima- 

 tion. In the case of seeds, meals, and feeds of a similar character, no great error is 

 introduced by such a determination (since from these materials the solvent takes 

 nothing but fat), but in the case of green fodders the difference between the crude fat 

 (including resins, gums and chlorophyll) nnd the true or pure fat or oil is frequently 

 very large. Hence, we decided in these analyses to employ a discriminating method, 

 and the figures given, therefore, represent true fat. 



It would seem lhat the younger plants are the richer in fat, and this evidently 

 in a large measure is due to the fact that the proportion of foliage to stalks is greater 

 in them than in the more mature plant. This would probabV not hold true to so great 

 an extent in rape grown broadcast. The stalks (ISTo. 6) are seen to contain but one- 

 tenth the amount of the fat in the foliage (No. 7). 



Fibre. — As might be expected, the percentage of this constituent increases with 

 the age of the plant. The stalks are naturally more fibrous than the leaves (compare 

 jSTos. 6 and 7), and since they (the stalks) are more prominent as the season advances 

 the analysis of the whole shows an increasing fibre content. In speaking of the relative 

 development of stalk to leaf, it may be of interest to state that in the rape collected 

 August 24, the proportion of stalk (taken from the ground to the base of the lowest 

 leaf) to leaf was 1 to 4, by weight. In rape sown broadcast, the proportion of stalk 

 would probably be much less. 



Crude Protein.— This term is applied in a comprehensive sense and is used to 

 include all the nitrogenous substances of the plant. In the case of seeds — including 

 grains of all kinds and their milling products — this involves but little error, since 

 practically all their nitrogen exists in the true albttminoid form. For such substances 

 the amount' of ' crude protein ' is a true indicator of their food value for furnishin. 



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