Íslenskar landbúnaðarrannsóknir - 01.03.1977, Síða 16

14 ÍSLENZKAR LANDBÚNABARRANNSÓKNIR
SUMMARY
STUDIES ON PHLEUM PRATENSE
(ENGMO).
II-Losses of dry matter and reduction of
digestibility of hay during drymg
in the field.
Bjarni Guðmundsson
Agricultural Research Institue, Hvanneyri, lceland.
The effects of field-drying on the losses of
dry matter and the reduction of digestibility
(in vitro) in Phleum pratense hay were in-
vestigated in ten experiments during the
years 1969—1973. The experiments were
located at Hvanneyri (64° 34'N, 21° —
40'W). The sward was cut with a rotary
mower and the hay was turned with a
swath turner (inclined rotating head). In
these experiments the hay was collected at 30
to 45 % moisture content — a suitable level
for barn drying.
There appeared to be an almost linear rela-
tion ship between time of field drying and
losses of dry matter and digestible dry matter,
the Iosses increasing by 0,9% and 1,3%
per day, respectively. With advancing stage
of maturity the losses decreased, probably due
to decreased proportions of leaves in the
crop. The main losses of dry matter and
reduction of digestibility were found in the
leaves whereas the stems maintained their
digestibile dry matter quite well, even under
very unfavourable drying conditions in the
field. The losses of digestible crude protein
were quite similar to those of digiestible dry
matter.
The reduction of the rotating speed of
the swath turner form 540 rpm (pto) to 400
rpm resulted in slightly lower losses of dry
matter, the difference being statistically in-
significant.
The dry matter digestibility of the hay
after fielddrying was strongly influenced by
the dry matter digestibility of the grass at
cutting and to a lesser extent by the length
of the field-drying period. The results indicate
that a determination of the stage of maturity
can be of help in deciding the dates at wich
the grass should be cut in order to obtain for-
age of a particular digestibility value (energy
value).