Íslenskar landbúnaðarrannsóknir - 01.03.1969, Side 65

EFNAINNIHALD OG MELTANLEIKI ÚTHAGAPLANTNA 63
S U M M A R Y
THE CHEMICAL COMPOSITION AND DIGESTIBILITY
OF SOME ICELANDIC RANGE PLANTS II
RANGE STUDIES IN ICELAND
Ingui Þorsteinsson and Gunnar Ólafsson,
Agricultural Research Institute, Reykjavik, Iceland.
The present paper deals with studies on the digestibility and chemical com-
position of 10 common Ieclandic range plants which are listed in Table 1.
The plant samples were collected at two locations in the lowlands, Hvann-
eyri and Heiðmörk, in the periods May 1965 to June 1966. Each species was
collected twice a month during the period May—September, and once a month
during the winter, weather conditions permitting. Only current growth was
sampled.
The phenological stage of the species at each sampling date was recorded
(Table 3).
The samples were analyzed for crude protein, calcium, magnesium, phos-
phorus and potassium. The digestibility of dry matter was determined by the
In-Vitro method.
The results are presented graphically on pages 50—62 and are percentages of
dry matter. The results are briefly discussed.
The main conclusions from these and previous studies (I’orsteinsson and
Ólafsson, 1965) are:
1) There is a reduction in the digestibility of dry matter and the percentage
of crude protein, phosphorus and potassium with increasing maturity of
the plants. At the same time there is an increase in calcium and mag-
nesium.
2) By the end of August the nutritive value of the range plants has become
lower than desirable.
3) At that tirne all the species studied had reached maturity after a growing
season of 2y2—3 months.
HEIMILDARRIT
Bliss, L. G., 1962: Adaptations of arctic and
alpine plants to environmental conditions.
Arctic, 15, 2.
Breirem, K., 1957: Forelesninger i vitaminer
og mineralstoffer ved Norges Landbruks-
h0gskole (referat av O. B. Vagnild). Volle-
bekk 1957.
Dukes, H. H„ 1943: The physiology of dome-
stic animals.
Veöráttan 1965. Ársyfirlit, samið á Veðurstof-
unni.
Veðráttan 1966. Ársyfirlit, samið á Veðurstof-
unni.
hORSTEINSSON, Ingvi og ÓLAFSSON, Gunnar,
1965: Efnainnihald og meltanleiki nokk-
urra úthagaplantna. llit Landbúnaðar-
deildar, A-flokkur, 17.