Bluegrass lawns are good for rabbits.

[James]

Having your rabbits in your Kentucky bluegrass lawn is probably good
way of getting fiber in their diet.

http://www.fs.fed.us/database/feis/plants/graminoid/poapra/management_considerations.html

"The National Academy of Sciences [84] reported the following
nutritional
information for fresh, aerial parts of Kentucky bluegrass during
various
growth stages:

% Protein % Ash % Crude Fiber % N-free
Extract
growth stage (N x 6.25)

immature 17.5 9.4 25.4 44.2
early bloom 16.6 7.1 27.4 44.9
mid-bloom 13.2 7.6 29.2 46.1
milk stage 11.6 7.3 30.3 47.2
dough stage 9.5 6.6 34.8 46.0
mature 9.5 6.2 32.2 49.0
over ripe 3.3 6.3 42.1 47.0"

[James]

Timothy info

http://www.fs.fed.us/database/feis/plants/graminoid/phlpra/all.html

NUTRITIONAL VALUE :
The nutritive value of timothy decreases as plants mature; the
digestibility of cellulose is directly proportional to overall
nutritive
value of timothy [8].

Crude protein, phosphorus, and carotene levels of timothy decline over
the course of the growing season. Some nutritional values for timothy
are as follows [56]:

dry crude crude crude ash Ca P carotene
matter protein fat fiber (%) (%) (%) (mg/kg)
(%) (%) (%) (%)
STAGE
leaf stage 92.2 13.3 3.17 24.3 7.23 0.37 0.20 45.2
heading 92.6 7.20 2.57 28.3 5.13 0.22 0.12 29.8
seed ripe 94.4 5.70 2.10 29.7 5.50 0.25 0.08 5.80
cured 93.0 2.94 1.86 34.4 7.30 0.38 0.04 2.12
weathered 95.1 2.45 1.20 42.5 4.85 0.26 0.03 1.00

Moisture content of timothy decreases as the plant matures; before
heading, moisture content is 78.5 percent; at full bloom, moisture
content is 67.2 percent; and as seeds mature, moisture content is 49.9
percent [46].

Feeds with low digestibility have a low net energy value; the net
energy
value of timothy hay is 43 therms. The best time to cut grass for hay
is a few days after it has reached the stage of maximum flowering and
before seeds begin to form. It will yield a greater return of
digestible nutrients per acre [57]:

Yields of digestible nutrients per acre of timothy cut at different

stages of growth (in pounds)

dry matter crude carbos crude fat total
digestible
protein matter
STAGE
early bloom 3.41 135 1.68 43 1.91
full bloom 4.00 147 1.87 44 2.11
seed formed 4.01 113 1.80 51 2.03
seed in dough 4.04 98 1.70 54 1.91
seed ripe 3.75 92 1.58 38 1.75