6. Rabbit Management 
Vol. 12, No. 8 
Page 3 
G. B. Rose 
The energy consumed, energy assimilated, and assimilation efficiencies of grow¬ 
ing young rabbits were measured and compared with those of adult rabbits. The young 
animals were kep' in cages and fed a diet of evaporated milk, rolled oats, and com¬ 
mercial rabbit chow. The caged adults were fed only the rabbit chow. 
Although the total amount of energy assimilated per animal per day increased 
with body weight (from about 30 kcal/animal/day for juvenile animals weighing be¬ 
tween 100 and 125 grams, to 97 kcal/animal/day at a body weight of 570 grams, to be¬ 
tween 100 and 175 local /animal /day for adult animals weighing between 1,000 and 1,200 
grams) it increased more slowly than did body weight, so that the amount of energy 
assimilated per gram body weight per day decreased (from between 0.27 and 0.37 kcal/ 
g/day for animals weighing between 100 and 200 grams, to 0.17 kcal/g/day at a body 
weight of 570 grams, to 0.15 and 0.09 for adult animals weighing between 1,000 and 
1,200 grams). 
Although animals were fed ad libitum on the mixed diet mentioned above, the 
amount of commercial rabbit chow eaten relative to the total energy consumed tended 
to increase as the animals grew older (from between 1 and 46 percent for animals 
weighing between 100 and 300 grams, to between 27 and 55 percent for animals weighing 
between 300 and 600 grams). The percentage of rabbit chow in the diet of an animal 
was inversely related to its assimilation efficiency. Thus, animals consuming less 
than 2 percent of their energy in the form of rabbit chow had assimilation efficien¬ 
cies of greater than 99 percent. Assimilation efficiencies decreased with increasing 
percentages of rabbit chow consumed until those animals consuming between 50 and 60 
percent rabbit chow had assimilation efficiencies of 77 to 82 percent, and animals 
fed only rabbit chow had assimilation efficiencies of 59 to 75 percent. Thus, the 
rabbits assimilated more than 99 percent of the energy of the evaporated milk and the 
rolled oats and an average of 68 percent of the energy of the rabbit chow. A mixed 
diet such as this, where the animals can choose different foods, is not adequate to 
determine whether the assimilation efficiencies of animals change with growth. It 
will be necessary to feed growing animals a diet consisting of a single item, i.e., 
rabbit chow, to determine differences in assimilation efficiency as the animals 
mature. 
