512 



EXPERIMENT STATION RECORD. 



versa. Exact numerical relations can not be established, as the natural 

 variations in digestibility, as well as the unavoidable errors connected 

 with the experiments, are sufficiently large to prevent obtaining exact 

 data for the depression in digestibility. The investigator on this point 

 should proceed very carefully and should make the separate periods 

 as long as possible. 



According to oar present knowledge, it is very desirable in conduct- 

 ing ordinary experiments on the digestibility of feeding stuffs to avoid 

 rations with extreme nutritive ratios. 



ACCURACY OF THE RESULTS OF DIOESTKW EXPERIMENTS. 



The so-called digestion coefficients are, of course, not absolutely exact, 

 for they include all the errors of the work and are affected by the indi- 

 viduality and by temporary variations in the digestive ability of the 

 experimental animals. Every large series of digestion experiments 

 with a feeding stuff shows variations in the digestion coefficients. To 

 make this clear the writer has calculated the variations in 57 separate 

 experiments with steers fed meadow hay alone, and has found the fol- 

 lowing variations in the digestion coefficients obtained with one and 

 the same animal in different trials: 



Variations in digestion coefficients for meadow hay by tin- same steer in different trials. 



Dry matter 



Organic matter 



('rude protein 



Nitrogen-free extract 



Crude fat 



Crude fiber 



The significance of these figures may be shown by an example. Sup- 

 pose the digestibility of wheat bran is to be determined. An experi- 

 ment is first made with average meadow hay, and following this au 

 experiment in which 10 kg. of this hay and 2 kg. of wheat bran are fed. 

 The variations which may occur in the nutrients digested from the hay 

 are as follows : 



Variations in amount of nutrients digested from meadow hay. 



