5Q2 NUTRITION OF FARM ANIMALS 



The system had the advantage of simplicity. Experience had 

 afforded a fairly definite idea of the quantity of hay required 

 for a given amount of production. It was only necessary to 

 compute from the hay values what weights of the available 

 feeding stuffs would produce equal effects. The simplicity of 

 the calculations, due especially to the fact that the relative 

 value of a feed was expressed by a single fixed number, led to 

 a rapid adoption of the system. " To each feeding stuff a defi- 

 nite hay value was assigned and in a short time one had a 

 beautiful table constructed which gave the most exact infor- 

 mation regarding the value of the most diverse feeding materials 

 in comparison with hay. Anything which appeared in any way 

 suited for feeding found its place in the table and each new 

 feeding stuff which the progress of agronomy provided, directly 

 or indirectly, was likewise quickly incorporated. It went so 

 far that even the salt supplied to the animals was computed in 

 hay values." l 



Thaer himself based his figures in part on the results of prac- 

 tical experiments. Numerous subsequent investigators carried 

 out direct comparisons of feeding stuffs on an extensive scale 

 and not one but several tables of hay values were formulated. 

 Unfortunately, these tables differed widely from each other, 

 some of them giving two or three times as great a hay value as 

 another to the same feed. It was evident also that the un- 

 limited substitution of different classes of feeds, as for instance 

 of grain or roots for hay, was impossible. Such discrepancies 

 and limitations led to various modifications of the methods of 

 estimating the hay values. Boussingault regarded the protein 

 content of the feed as the principal factor, while Nathusius took 

 into account also the content of crude fiber and Wolff z worked 

 out a somewhat elaborate method in an attempt to retain the 

 convenience of reckoning with a single number for a feed. The 

 impossibility of this, however, gradually came to be recognized, 

 and the hay values have now only a historical interest. 



701. Practical feeding trials. But while the system of 

 hay values has become obsolete the idea of determining the 

 relative nutritive values of feeding stuffs on the basis of direct 

 comparisons of the results obtained in practice has survived in 



1 Settegast, Die Fiitterungslehre, 1879, p. 4. 



2 Die landwirtschaftliche Fiitterungslehre, 1861, pp. 455-456. 



