Nutritive Value of Redtop Hay Cut at 

 Different Stages of Maturity 



N. F. C0I0VO8, J. B. Holler, N. K. Peterson 

 P. T. Blood and H. A. Davis 



Introduction 



A considerable amount of information has become available in the 

 Northeast and in other parts of the United States on the composition 

 and digestibility of different forages grown under varying levels of nitro- 

 gen fertilization and harvested at defined stages of maturity. This has 

 been due mainly to the efforts of contributors in the experiment stations 

 participating in regional research projects throughout the country, espe- 

 cially in the forage growing regions. Some information on acceptability of 

 forages by ruminants has also been published since the early fifties 

 when Crampton (7) proposed that forages should be evaluated on the 

 basis of their nutritive value index. 



Despite this large volume of information on digestibility, and some 

 recent results on acceptability of forages, little has been published on 

 the utilization of the digested components of these forages for main- 

 tenance or production. Most of such published information comes from 

 European countries, Japan, and recently from the U.S.D.A. Energy Lab- 

 oratory at Beltsville, Maryland (2, 8, 9) . 



The New Hampshire Agricultural Experiment Station has been ac- 

 tively engaged (3, 4, 5, 6, 10, 11) in energy metabolism research for 

 several years and, by the use of indirect calorimeters, has been conduct- 

 ing complete energy balance studies with ruminants, determining the 

 nutritive value of different forage species grown in the Northeast. 



This bulletin reports the results of a two-year study of the nutritive 

 value of redtop hay grown with 100 pounds of nitrogen per acre and cut 

 at three stages of maturity. The nutritive value of these hays, determined 

 by using both cattle and sheep, is presented on the basis of several 

 methods of evaluation — total digestible nutrients, digestible protein, 

 digestible energy, metabolizable energy, and net energy. 



