GROWTH 399 



Energy requirements 



480. Computation from daily increase. The estimates 

 contained in the foregoing table of the amount of energy 

 stored up in growth, although unfortunately based on scanty 

 data, show, to the extent to which they can be relied on, 

 the amounts of net energy which are necessary for the 

 support of growth without any considerable fattening. 

 Since the results described in 2 render it probable that 

 the net energy values of feeding stuffs for growth do not 

 differ widely from those for maintenance or for fattening (477), 

 the figures of the table, with the addition of the maintenance 

 requirement, would afford a basis for computing rations for 

 young animals. 



481. Computation from gain in live weight. Another 

 method of computation furnishes to a certain degree a check 

 upon the results recorded in the last table. The amount of 

 energy stored up in the increase at different ages may be esti- 

 mated by applying the results regarding the energy values per 

 unit of increase which are recorded in Table 79 (458) to the gain 

 of live weight actually observed in the growth of animals under 

 normal conditions. 



a. Cattle. From data secured at the Missouri Experiment 

 Station l regarding the rate of growth of 5 Hereford, 6 Jersey, 

 2 Ayreshire and 5 Holstein calves, the writer has computed 

 the following figures for the daily gain of energy per 1000 pounds 

 live weight by calves. 



For an animal one month old, it is assumed that the energy con- 

 tent of the increase in live weight was the same as the average of 

 Soxhlet's respiration experiments, viz., 1170 Cals. per pound, and 

 that this increased at a uniform rate to a maximum of 3000 Cals. per 

 pound at 1 8 months old. The observed daily gain of energy has been 

 computed per 1000 pounds live weight to eliminate the influence 

 of the varying size of the different breeds. The average daily gains 

 per 1000 pounds live weight are computed for each breed separately, 

 and these means are again averaged, i.e., each breed has been 

 given equal weight. None of the animals were fattened to any great 

 extent. 



1 Private communications from Professors P. F. Trowbridge and C. H Eckles. 

 Data for the dairy breeds have been published in Bui. 135 of the Missouri Station. 



