OAP. vin. SWEET AND SOUR SILAGE. 845 



which can be better spared during the slacker time of feeding the 

 silage, in winter. Besides this it is no longer found necessary to 

 feed the silage in a chaffed form, and it is now more generally fed in 

 the long condition, as rack-meat. A comparison of samples of silage 

 made under similar conditions, except with respect to chaffing, will 

 show that the chaffed is greener in colour than the unchaffed. This 

 is a proof that pressure has a more immediate effect on the chaffed 

 material, and that the latter is consolidated more quickly, thus causing 

 the fermentation to be brought about at a lower temperature. 



This brings us to the question of sweet and sour silage. If an open- 

 air silage stack is viewed in section from top to bottom, the lower 

 layers will be seen to be greener than . the upper, gradually becoming 

 browner towards the top, which, under a small layer of dirty mould, 

 will be of almost a burnt coffee colour. The bottom layers have been 

 converted into green or sour silage, because the pressure of the material 

 above has excluded the air, and a low temperature fermentation has 

 taken place, there not having been sufficient air to supply the oxygen for 

 a high temperature fermentation. As less weight was applied to the 

 upper portion there was a, freer access of air to it, and more air retained 

 among the mass, hence a higher fermentation. The colour thus 

 affords an indication of the temperature at which the fermentation' took 

 place. It is generally recognised that silage made at a temperature 

 below 120 F. is sour silage, whilst that which has not risen above 

 90 F. is commonly spoken of as low-temperature sour, and that 

 which has exceeded 90 F. as high-temperature sour. Between 120 

 and 130 there are generally veins or seams of sweet and sour silage. 

 From 130 to 140 a shade of brown is discernible. Between 140 

 and 160 it is decidedly brown ; and above 160 it is over-heated, and 

 very similar in appearance to over-heated hay, whilst the flavour 

 denotes burning. It was supposed that, when the temperature of 

 fermentation exceeded 123, no acids would be present ; but, in the 

 experiments carried out at Bristol for the Bath and West of England 

 Society this was not found to be correct, for, though the greatest care 

 was taken in the manufacture of the various kinds at different tempera- 

 tures, acids were present in all. Another practical result was obtained 

 from these experiments in determining the loss of weight by evapora- 

 tion and otherwise : 50 cwt. of grass was dealt with in each case, and 

 the respective losses are shown in the following table : 



cwt qrs. Ib. 



1. Sour Silage (long) 4 2 5= 9 '10 per cent, (weighted with 200 Ib. per sq. ft.) 



2. Sour Silage (long) 4 2 15|= 9'28 , 100 



3. Sweet Silage (long) 9 22 = 18*40 



4. Sweet Silage (long) 30 1 6 = 60'61 



(ensiled at once) 



(dried 24 hours in hot sun before 



making) 



5. Sour Silage (chopped) 2 1 0= 4 '50 



6. Sweet Silage (chopped) 4 3 22= 9 '89 



7. Hay 36 3 26 = 73 '97 



The great variation in the loss shows that samples of silage made 

 under different circumstances with regard to heat had dissimilar values, 

 especially in the case where the grass was allowed to wither before 



