10 UNIV. OF N. H. AGE. EXPERIMENT STATION [Bulletin 216 



Nutrition Studies. 



In this project, which is conducted in co-operation with the Nutrition 

 Laboratory of the Carnegie Institution of Washington, two purebred Shorthorn 

 steer calves just one year of age were purchased to check the problem of metab- 

 ohsm on undernutrition and also that of basal metabolism during growth. 

 These calves, together with the two older steers, used the two preceding years, 

 were therefore studied by E. G. Ritzman (Animal Husbandry), and Dr. F. G. 

 Benedict of the Nutrition Laboratory, under identical conditions. All four 

 animals were subjected to a submaintenance test of about three months, i.e., 

 about the length of time required by the 14 steers, reported on previously^ to 

 reach the lowest level of metabolism under similar conditions. They were then 

 subjected to short fasts of five to seven days for a study of basal values. Fol- 

 lowing this, they were re-fed on hay and grain and used for continuous three- 

 day metabolism experiments in the respiration chamber to correlate the so- 

 called standard experiments (in which the animal, after 24-hours' fasting, is in 

 the chamber for a two-hour respiration experiment) with the entire 24-hour 

 condition. The work has, therefore, been partly that of studying the problems 

 of technique as well as a study of the metabolism of growing steers. 



In addition to the work done here, an investigation on the composition of the 

 urine of these steers while fasting was carried on by Dr. T. M. Carpenter of the 

 Nutrition Laboratory. Especial attention was given to the relationship of 

 three forms of sulphur; viz., inorganic and ethereal sulphates and neutral sulphur 

 as affected by various planes of nutrition. The daily urinary nitrogen excre- 

 tion has been determined over a period of 71 days, and the effect of storage 

 upon the quantity of ammonia has been observed. One objective of Dr. 

 Carpenter has been a simphfication of method to determine the potential 

 energy of urine by means of an oxidizing agent. 



In addition to Publication No. 324 issued by the Nutrition Laboratory of the 

 Carnegie Institution of Washington on the first two years' investigation, a 

 more condensed report covering the same period of work was issued this year in 

 N. H. Station Bulletin No. 25. This bulletin is a digest of a research on under- 

 nutrition in steers, discussing the findings with the particular object of pointing 

 out their economic significance under the extremely varying feed levels such as 

 are commonly met with on the farm and range and their influence on the general 

 practice of feeding live stock. The rate of all vital activities appears to vary 

 closely with the changes in level of the feed. The pulse rate, heat production, 

 glandular secretion, and physical activity all decreased with reduced rations. 

 This whole picture was completely reversed when fattening rations were given. 

 Health was in no single case impaired by nearly four months of undernutrition, 

 and there was no evidence that it limited the regain of flesh and fat lost. 



It is shown that the rate of regain in weight of steers which have been 

 brought through a whole winter period on 50 per cent submaintenance is ex- 

 ceedingly rapid. Even those steers which received only pasture grass regained 

 their original weight in less than three months and, in fact, pasturage proved to 

 be the most economic method of recovering the weight lost by undernutrition. 



It is also clearly established that rations high in protein are particularly 

 uneconomic in fattening, since the amount of nitrogen that a mature steer can 

 assimilate daily is relatively limited. 



