1957 - 1958 



The first hays, grown under two levels of nitrogen fertilization. 50 and 

 200 pounds per acre, were harvested at three stages of maturity during 

 the Spring of 1957. The digestion balance experiments were run during 

 the period of October 1957 and May 1958. 



The animals used in this experiment were identical twin Holstein 

 steers. These same animals were used throughout the three years' experi- 

 mental period. 



1958-1959 



The hromegrass hays for this year's experiments were grown under 

 four levels of nitrogen fertilization, 50 lb.. 100 11)., 200 lb., and 400 lb. per 

 acre, and harvested at three stages of maturity June 4. June 13. and June 

 23, 1958. Due to severe lodging in the 400 11). N acre, digestion balance 

 experiments were run only on the June 4 cutting. The nutritive value of 

 ten hays was determined during this year. Digestion balances were run 

 fluring the period of September 1958 and June 1959. 



A second cutting of the crop on all fertilizations was made on July 20, 

 1958 on representative })lots to determine the total crop on each treat- 

 ment but no digestion balances were obtained with the animals. 



1959 - 1960 



The experiment was repeated with the ten hays grown and harvested 

 as in the previous years. A second cutting crop estimate was made on all 

 fertilizations from representative plots harvested on July 20 as in the 

 previous year. Digestion balances were run during the period of Septem- 

 ber 1959 and June 1960. 



Procedures 



The procedure and methods followed in this experiment differed very 

 little from those used in previous research reported from this laboratory 

 except in the method of the excreta collection. A brief description of the 

 procedure and methods is presented below together with the changes 

 made. 



Feed 



The hays were chopped and mixed thoroughly before they were trans- 

 ported into the laboratory in large burlap bags. The hays were fed to the 

 animals twice a day at which time an aliquot sample was taken to com- 

 posite it for analysis. A salt block was kept in front of each animal at all 

 times. A preliminary period of 15-18 days was allowed before each di- 

 gestion balance collection. 



Collection periods were of 8 days duration. During the collection peri- 

 ods any refuse was carefully recovered, dried and compounded for an- 

 alysis. 



Gross energy determinations of the feed and refuse were made by the 

 use of an adiabatic bomb calorimeter. Proximate analyses were made on 

 both feed and refuse. The nitrogen and the energy in the refuse were sub- 



13 



