260 



LACTIC ACID BACTERIA IN FODDER. 



into withered (air-dried) hay and the other to brown hay ; and an 

 average sample of each was subjected to analysis : 



A comparison of the first and third lines of this table at once 

 reveals the high percentage of lactic acid and butyric acid in the 

 brown hay, both of which are entirely absent from air-dried hay. 

 It will be evident, upon mature consideration, that the production 

 of these acids by bacterial activity does not occur in the centre of 

 the stack, since the temperatures (7o-9o C.) prevailing there are 

 such that only the passive reproductive forms of these organisms 

 are able to withstand. To obtain a correct idea, we must picture 

 the changes occurring within the stack as proceeding in the follow- 

 ing manner : the thermo-bacteria develop in the centre of the 

 mass and liberate heat which radiates towards the outside. Be- 

 tween this hot central layer and the external strata exposed to the 

 cool air lies a broad zone wherein the precise temperature (40- 

 50 C.) most suitable for the development of the acid bacteria in 

 question prevails. The metabolic products from these organisms 

 then gradually permeate the entire mass. The chief material for 

 these fermentations is afforded by carbohydrates (starch), as may 

 be seen from the foregoing table, according to which the air-dried 

 hay contains 40.9 per cent., whilst the brown hay contains only 

 23.2 per cent, of non-nitrogenous extractive matter (starch, sugar, 

 &c.). Of the nitrogenous constituents, those soluble in water, i.e. 

 amides and kindred bodies of which the brown hay contained 

 i.i per cent, and the air-dried hay 3.0 per cent. are for the most 

 part consumed. The loss of matter attendant on the preparation 

 of brown hay is calculated by Dietrich as about 14 per cent. 



Brown hay exhibits one advantage over both air-dried hay 

 and burnt hay, namely, that its preparation is much less dependent 

 on the weather, a couple of fine days sufficing for protecting the 

 finished hay. These days can, however, be selected at con- 

 venience, since the ricks of brown hay can be left untouched for 



