PRESERVATION OF FORAGE 29 



content is reduced to 20 per cent. It is rarely practicable, 

 however, to make moisture determinations. Among 

 empirical rules used to determine when curing is so far 

 completed to make housing safe are (1) when the hay 

 breaks if a wisp is tightly twisted in the hand ; (2) when 

 it is dry enough to rattle if gently shaken ; and (3) when 

 it no longer feels cool if pressed to the cheek. 



23. Shrinkage of stored hay. Hay when stored con- 

 tains a varying amount of water, depending on the thor- 

 oughness of the curing. Even in very dry climates it is 

 seldom less than 10 per cent and in moist climates or under 

 unfavorable conditions is commonly as high as 25 per 

 cent. In the West hay is often stacked when the moisture 

 content exceeds 25 per cent, and instances are reported 

 where it contained as high as 38 per cent and yet kept well. 

 The average moisture content of cured hay ranges from 

 15 to 20 per cent. 



Shrinkage is mainly due to loss of water ; in rare cases 

 where the hay is put in the mow when very dry, there may 

 be gain in water content. Shrinkage due to loss of moisture 

 varies according to the water content when stored and the 

 humidity of the air. 



Besides the shrinkage due to evaporation of moisture, 

 there is a varying amount of loss due to oxidation. Even 

 in well cured hay the enzymatic changes which go on cause 

 a small loss by oxidation. In poorly cured hay the loss 

 may be much greater, not only from the high degree of 

 heat engendered by the preliminary fermentation, but 

 also by the growth of destructive molds and other 

 organisms. 



The actual shrinkage which takes place in stored or 

 stacked hay has been determined at several experiment 

 stations. 



