Vo 1. 14, No. 7 
Page 4 
The growth per day for the caged cottontails averaged 0.29 gram, or an 
estimated 0.50 kcal/day, and ranged from a loss of 3*27 kcal to a gain of 
5.34 kcal. The percentage of the energy consumed that was represented by 
growth (for the 7 animals that gained weight out of 10) was O .76 (range, 
0.06 to 1.94), while the net growth-efficiency averaged 1.24 percent (range, 
0.11 to 3*17 percent). 
Thus, although growth continued in adult animals, the net growth- 
efficiency is approximately 1 percent, and the remaining 99 percent is 
respiration. 
The low, net growth-efficiency of adult rabbits is in expected contrast 
to higher net growth-efficiencies for juveniles, as expressed by the equation 
y = 40.44 - 0.038X, when X is body weight and Y is percentage net growth- 
efficiency (Rose, G. B. 1970. Job Progress Report, unpublished). 
