ii6 Journal of Agricultural Research voi. xxn. no. 3 



METHOD OF THE EXPERIMENT 



RATIONS 



The concentrate consisted of the following mixture: Com chop, 60 

 per cent; wheat bran, 30 per cent; linseed meal, 10 percent. The rough- 

 age fed to the 3 old steers. No. 528, 589, and 585, from the beginning of 

 the experiment until July 20, 191 7, was timothy. For the next 10 days 

 a mixture of 5 parts timothy, 3 parts alfalfa, and 2 parts oat straw was 

 fed. Following this the roughage consisted of a mixture of 60 per cent 

 alfalfa amd 40 per cent oat straw. The animals were fed twice daily and 

 had access to water at all times. Salt was accessible at feeding time. 



PERIODS 



The calculations are made for periods of 180 days, with the exception 

 of the first period for the 3 older steers, which was as follows: No. 528, 

 130 days; No. 579, 142 days; No. 585, 150 days. The warm months 

 of the year were selected for these periods to avoid a possible disturbing 

 effect of low temperatures in the winter months. 



WEIGHTS 



The steers were weighed each morning after feeding but before water- 

 ing. The weight given for the beginning of a period is the average of the 

 10 preceding days. The weight given at the end is an average of the last 

 10 days of the period 



ENERGY INTAKE 



The amount of dry matter consumed was calculated from the weight 

 and composition of the feed consumed. The net energy was computed 

 from this by the use of factors reported by Armsby and Fries. ^ For the 

 concentrates the value 83.82 therms per 100 pounds dry matter was used. 

 This is the factor given for Armsby's grain mixture No. 2,- which approxi- 

 mates the grain mixture used in this experiment. For timothy hay the 

 value 48.63 therms per 100 pounds dry matter was used. The factor for 

 the roughage mixture used in the latter part of the experiment was cal- 

 culated from the Armsby values, for alfalfa, 34.10 therms and for oat 

 straw, 26.03 therms per 100 pounds dry matter. A mixture of 60 parts 

 alfalfa and 40 parts oat straw would have a value of 30.87 therms per 100 

 pounds dry matter. The calculations of the energy value of the milk are 

 based on factors published by Armsby.^ There are 29.01 therms per 

 100 pounds whole milk (4.4 per cent) and 14.31 therms per 100 pounds 

 skim milk (0.2 per cent). From these values factors were computed for 

 the different grades of milk used. 



'Armsby, H. P., and Fries, J. A. op. cit. 



2 Annsby's grain mixture No. 2, 60 per cent com meal, 30 per cent crushed oats, 10 per cent O. P. linseed 

 meal. Our grain mixture, 60 per cent com meal, 30 per cent wheat bran, 10 per cent O. P. linseed meal. 

 ^Armsby, Henry Prentiss, thb nutrition op farm animals, p. 719. New York, 1917. 



