tractcd from the amount fed in order to determine the protein and en- 

 ergy consumed hy the animal and aL<o oljtain s-ome of the data for the 

 determination of the total digestible nutrients. 



Excreta 



Feces and urine from the steers were collected separately by means of 

 collection devices developed at this laboratory ( 3 » . These consist of 

 metal containers placed in the opening under the floor and directly in 

 back of the metabolism stall to receive the feces when the animals defe- 

 cate. Urine goes into stainless steel funnels which are in the center of 

 each stall and covered by a grid, and is directed into a bottle in the base- 

 ment. Both urine and feces are collected in the basement where the temp- 

 erature is kept much cooler than the rest of the building. 



Feces and urine were weighed and sampled daily. Composite samples 

 of feces were kept at a temperature of approximately — 16° C. while the 

 composite samples of urine were stored at a temperature slightly above 

 fxeezing. At these temperatures no preservative is necessary. At the end 

 of the collection period, the feces samples were thawed, mixed thorough- 

 ly and an aliquot was taken for moisture, nitrogen and gross energy de- 

 terminations. The remainder of the sample was spread in a shallow pan 

 and drie<l in a forced hot air oven at a temperature of 55° C. and then 

 ground in a Wiley mill. Gross energy was determined on the dry feces as 

 well to check for anv loss due to volatilization during the process of dry- 

 ing (8). 



Urine samples were allowed to come to a temperature of aliout 20° C, 

 and their specific gravitv determined; they were analyzed for l)oth nitro- 

 gen and gross energy. The urine samples used for the gross energy de- 

 terminations were dried in the combustion capsules under vacuum. 



Results and Discussion 



The composition of the broniegrass hays grown under the levels of ni- 

 trogen fertilization of the experiment and harvested at the three stages 

 of maturity are shown in Table 1. The letters E, M. and L before the 

 numJjers under the forage column denote early, medium, and late cut- 

 tings, or about June 1, 10, and 20 respectively. The number after each 

 letter denotes the weight in nounds of nitrogen fertilization per acre. 



The proximate analyses of the three years' crops differed little when 

 compared on the basis of date of harvest. The protein, ether extract, and 

 ash percentage composition decreased while the crude fiber and nitrogen- 

 free extract increased as the harvest was delayed. 



The protein content in the early-cut hays of the two higher fertiliza- 

 tions. 400 lb. and 200 lb. nitrogen per acre, ranged between 16 and 23 per 

 cent. This is in agreement with other investigators (2j who found protein 

 values in grasses as high as in legumes. 



Digestibilities of drv matter, protein and energy, as well as the total 

 digestible nutrients for the three years are shown in Table 2 and for 

 comparison in Figure 1. Digestibilities decreased as the date of cutting 

 was delayed. The decrease in the digestibilities of dry matter, protein, 

 energy, and total digestible nutrients averaged about one half of one 

 per cent per day of delay after the first of June. 



15 



