Nitrogen fertilization also increased TDN of
bahiagrass, but increases, when averaged over the
entire year, were relatively small (Table 1). In-
creases in TDN were most evident immediately
following N application (Figure 3). Fertilization
with P and K had little effect on crude protein
content and TDN of bahiagrass.
 TnM 1987


JUL AUG SEP OCT NOV DEC


S No Fert M 60 Ib N, March W 120 Ib N, March/Sept


1988


MAY JUN JUL AUG SEP OCT NOV DEC

S No Fert M 60 Ib N, March = 120 Ib N, March/Sept


1989


Quality of regrowth vs available forage

 Forage quality values for available forage
responded to fertilization in a manner similar to
that for regrowth forage (data not shown). How-
ever, available forage was lower in crude protein
content and digestibility than regrowth forage, and
from July through the fall this difference became
progressively larger (Figure 4). The crude protein
and TDN requirements for a brood cow nursing a
calf and having average milking ability are about
10% and 58% of the dry matter, respectively (Na-
tional Research Council, 1984). During the spring,
summer, and early fall, cattle would selectively
graze bahiagrass having quality similar to regrowth
forage which would come close to meeting the
requirements of lactating brood cows for crude
protein and TDN. However, in late fall and winter
when bahiagrass stops growing and forage availabil-
ity becomes limited, the quality of forage eaten by
cattle would be similar to that shown for available
forage harvested in October and December. This
forage would only meet the needs of dry, pregnant

 % Crude Protein
16
14
12 -







 Apr May Jun Jul Aug Sep Oct Nov Dec


'Regrowth' Forage M "Available" Forage


% TDN


0 1 i 1 in: :\: :' : -
 MAY JUN JUL AUG SEP OCT NOV DEC

 SNo Fert E 60 Ib N, March Li 120 Ib N, March/Sept
Figure 3. Effect of N fertilization on the TDN content of bahia-
 grass by month averaged over eight ranches in
 south Florida.


 Apr May Jun Jul Aug Sep Oct Nov Dec

 Regrowth" Forage "Available" Forage
Figure 4. Crude protein content and TDN in regrowth and
 available bahiagrass forage by month averaged
 over eight ranches in south Florida (three year
 average over all fertilizer treatments).