NET ENERGY VALUES OF ALFALFA HAY AND OF 



STARCH 



By Henry Prentiss Armsby, Director, and J. August Fries, Assistant Director, 

 Institute of Animal Nutrition of the Pennsylvania State College 



COOPERATIVE INVESTIGATIONS BETWEEN THE BUREAU OF ANIMAL INDUSTRY OF 

 THE UNITED STATES DEPARTMENT OF AGRICULTURE AND THE INSTITUTE OP 

 ANIMAL NUTRITION OF THE PENNSYLVANIA STATE COLLEGE 



INTRODUCTION 



The experiments here reported were undertaken primarily to deter- 

 mine the net energy value of starch as a representative of the carbohy- 

 drates. Alfalfa hay was used as the necessary roughage chiefly in order 

 to secure a mixed ration not too low relatively in protein, but in part also 

 for the sake of comparison with the results of several earlier determina- 

 tions on the same feeding stufif. 



OUTLINE OF EXPERIMENT 



The subject of the experiment was a pure-bred Shorthorn steer, des- 

 ignated as Steer J, bred by The Pennsylvania State College. He was a 

 year and lo months old at the beginning of the experiment and had been 

 chiefly grass fed up to that time. He was the same animal used in the 

 subsequent year for the experiment on the influence of the degree of fat- 

 ness of cattle upon their utilization of feed already reported.^ 



The general plan of the experiment was the same which has been em- 

 ployed in our more recent determinations of the net energy values of 

 concentrates. It consisted, first, in determining with the aid of the 

 respiration calorimeter, the net energy value of the roughage by a com- 

 parison of two or more periods in which different amounts of it were fed 

 and second, in making similar determinations upon a mixture of hay and 

 starch in the proportion of 2.5 to i. By a difference calculation, pre- 

 cisely similar in principle to that commonly used in estimating the 

 digestibility of a concentrate, the net energy of the starch could then be 

 computed.^ As a matter of fact, the trials were not actually made in 

 this order, those on the mixed ration preceding those on the hay. 



It may be noted that this method differs from that employed by 

 Kellner, who has also reported a number of determinations of the net 

 energy value of starch.^ In his experiments the starch was added to a 

 basal ration of hay and grain, the balance of carbon and nitrogen on each 



• Armsby, H. P., and Fries, J. A. influence of the degree of fatness of cattle upon their utili- 

 zation of feed, /w Jour. Agr. Research, V. II, no. 10, p. 451-472, pi. 41. Literature cited, p. 464. 1917. 



2 net energy values of feeding stuffs for c.\ttle. In Jour. Agr. Research, v. 3, 



no. 6, p. 469-470. 1915. 



' Kellner, O.. and Kohler, A. untersuchungen uber den stoff- und energie-umsatz des 

 ERwachsehen rindes bei erhaltungs- und PRODUKTioNSFUTTER. In Landw. Vers, Sta., Bd. 53, 

 474 p. 1900. 



Journal of Agricultural Research, Vol. XV, No. s 



Washington, D. C. Nov. 4, 1918 



qb Key No. Pa.-p 



(269) 



