8 



BULLETIN 873, U. S. DEPARTMENT OF AGRICULTURE. 



When data on these vital factors are included along with the 

 results of a shrinkage experiment, the loss or gain in weight, whether 

 it be large or small, at once becomes easy to interpret and will be 

 found to be in accord with the natural laws that govern the curing 

 of hay. 



Many shrinkage experiments have been made without determining 

 the water content, either at the time the hay was taken from the field 

 or at the end of the experiment. (See experiments 2, 4, 5, and 6.) 

 The hay was merely weighed when put into the barn or stack and 

 again at a specified later time and the amount of loss by shrinkage 

 was determined by the difference between the two weights. It is 

 the publishing of the results of such experiments, especially when a 

 comparatively large loss occurred, that has led many hay growers to 

 believe that an actual instead of an apparent loss takes place when 

 hay is in storage for some time. 



This belief has been further strengthened, in some instances, by 

 statements to the effect that besides the loss of water there has been 

 a loss of dry matter, because of fermentation (the amount of which, 

 however, is unknown) without giving adequate evidence to show that 

 any such loss has occurred or even that conditions were favorable 

 for fermentation. 11 The loss of dry matter will be discussed later. 



FACTORS AFFECTING DETERMINATION OF SHRINKAGE. 



FIRST FACTOR— WATER CONTENT WHEN CUT. 



There is a great difference in the amount of water contained in 

 grasses and legumes when cut, while curing or being made into hay, 

 and after becoming well-cured hay. A knowledge of the normal 

 water content of hay in these various stages will throw light on what 

 may be expected to happen during the final stages of curing. Table I, 

 compiled from Henry's Feeds and Feeding, shows the average water 

 content of different kinds of hay, as determined by a long series of 

 tests. 



Table I. — Water content of "unwilted" hay. 



Timothy, at different stages.. . 



Redtop, in bloom 



Red clover, at different stages. 



Alsike clover, in bloom 



Alfalfa, at different stages 



Cowpeas 



8oy beans 



Johnson grass 



Barley 



Oat 



Rye 



Wheat 



Average. 



Per 



cent. 

 61.6 

 65.3 

 70.8 

 74.8 

 71.8 

 83.6 

 75.1 

 61.0 

 76.8 

 73.9 

 78.7 

 72.6 



Minimum. 



Per cent. 

 47.0 

 51.5 

 47.1 

 72.3 

 49.3 

 72.8 

 63.6 

 51.1 



Maximum. 



Per cent. 

 78.7 

 76.2 

 91.8 

 77.3 

 82.0 

 93.1 

 81.5 

 70.8 



Difference 

 between 

 extremes. 



Per cent. 

 31.7 

 24.7 

 34.7 

 5.0 

 32.7 

 20.3 

 17.9 

 19.7 



ii Utah Agricultural Experiment Station, Third Annual Report, 1892, p. 47-48. U. S. Department of 

 Agriculture, Bulletin 353, 1916, p. 6, 17. 



