6 UNIV. OF N. H. AGR. EXPERIMENT STATION [Bulletin 240 



forms of apparatus which have now become standard equipment for the 

 study of problems in human nutrition, an attempt to achieve a similar 

 objective in nutrition studies with live stock appeared to merit concen- 

 trated effort. It is the purpose of this bulletin to report on the progress 

 made towards the achievement of this objective at the Laboratory for 

 Animal Nutrition at Durham. 



THE LABORATORY BUILDING 



The laboratory building is a single story, wooden structure with a base- 

 ment. The development to its present stage has been a gradual process 

 extending over a period of nine years. Originally it contained only the 

 center portion of the present building. This was composed (as shown in 

 Fig. 1) of a room fitted with two metabolism stalls for steers, a room con- 

 taining the respiration chamber and a platform scale for weighing the 

 animals, and a room containing the necessary electrical and physical 

 accessories. When the Purnell Fund became available to permit ex- 

 tension of this work to dairy cows, a wing providing a feed storage room 

 and space for two metabolism stalls for dairy cows was added. This was 

 followed two years later by the addition of a basement wing to provide 

 necessary laboratory facilities to handle the samples of feed and excreta 

 incident to digestion balances, and to provide space for several small 

 respiration chambers which are being used for metabolism work with 

 sheep. This basement also provides a small laboratory room for experi- 

 mental study of human dietaries. 



The last addition to the building, made during 1928, provides more fl.oor 

 space by the construction of a second floor on top of the basement wing 

 just mentioned. This furnishes a room to be fitted up for a milk labora- 

 tory, and two small offices with desks and files. 



The building is heated by steam, the radiators having suflEicient radia- 

 tion surface to keep the various rooms comfortable even during the coldest 

 days of winter. It is thus not difficult to maintain a relatively uniform 

 temperature, although experimentally constant conditions cannot be 

 maintained during great changes in outdoor temperature. 



The arrangement of the apparatus, stalls and other appliances is shown 

 in the floor plans, Figs. 1 and 2. 



Objectives in Laboratory Facilities and Technique and 

 Requirements in Apparatus 



The technical objectives of this laboratory have been to develop forms 

 of apparatus and of technique which combine speed and economy with 

 precision, and thus make available more economical and more expeditious 

 processes with which to determine energy balances of farm live stock under 

 varied conditions of nutrition. The apparatus and the technique of 

 procedure are, therefore, largely such as are based on principles and 

 methods of physics and of physical chemistry rather than of pure chem- 

 istry. 



Chemical determinations are involved only to a minor extent, that is, to 

 carry out nitrogen balances. Separate analyses of the nitrogen in urine 

 and in feces are essential, first, for the determination of the digestibility of 

 the various food constituents; second, to difl^erentiate the character of the 



