Vol. 12, No. 9 
Page 3 
control (August 1966); (2) burning one-half of the field in February 1 968 ; (3) burn¬ 
ing the remaining one-half of the field in August 1 968 . By the second fall (1 967 ) 
after seeding, the presence of each prairie grass was readily apparent and by late 
summer, 1969 , a luxuriant stand of the three prairie species resulted, particularly 
in the portion of the field that was burned in February I 968 . These responses 
suggest that prairie grass can be established more rapidly using oats and timothy 
w«th the initial seeding, followed by late-winter burning, than by the method of 
establishment initiated in I 963 . 
Numerous approaches to prairie restoration have been implemented since I 966 on 
sanctuaries in Jasper and Marion counties. Prairie grasses established to date are 
mainly of Nebraska or Kansas origin. Additional seedings have been made using hand- 
stripped seed from various native composites, legumes, and other forbs as well as 
grasses from local railroad and roadside rights-of-way. Recently, arrangements have 
been made to harvest seed by combining along the Illinois Central Prairie near 
Kinmundy in an effort to obtain a large quantity of seed from as many native species 
as possible, all of local origin. 
6. Rabbit Manag ement G . B< Rose 
The energy of assimilation and the energy of growth (secondary productivity) of 
caged young rabbits in various stages of growth were measured and compared. The 
youngest animals were fed a diet of evaporated milk, rolled oats, and rabbit chow 
the older animals were fed only rabbit chow. 
Respiration energy was estimated by subtracting the growth energy from the 
assimilation energy. Respiration per animal per day increased with body weight 
(from an average of 23 kcal/day for animals weighing between 100 and 125 grams, to 
an average of 137 kcal/day for animals weighing between 800 and 1,000 grams). The 
respiration energy per gram body weight decreased as body weight increased (from an 
average of 0.21 kcal/g body wt for animals in the 100- to 125-gram weight range to 
an average of 0.14 kcal/g body wt in the 800- to 1,000-gram weight range). 
The percentage of assimilated energy converted into growth (net growth- 
efficiency) decreased as body weight increased (from an average of 40 percent for 
an 1ma1s 1n the 100- to 200-gram weight range to 12 percent for animals in the 800- 
to 1,000-gram weight range). 
