Fjölrit RALA - 15.12.2000, Blaðsíða 31

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Table 30. Digestibility of DM (%) in Iceland on different harvest dates 1996 (n=3) and 1997 (n=2).
Harvest dates 1996
4.6. 18.6. 2.7. 16.7. 30.7.
Seida 81.6 77.1 71.5 65.8 62.3
Vega 82.1 78.0 72.8 68.9 67.6
Engmo 82.4 78.3 73.1 Harvest dates 1997 68.1 66.7
28.5. 10.6. 24.6. 8.7. 22.7.
Lavang 77.0 74.1 72.5 67.2 61.3
Fylking 77.2 75.3 74.1 68.8 65.2
Seida 77.5 73.7 70.8 66.9 61.3
Vega 80.9 77.7 75.2 70.5 66.9
Engmo 81.1 78.4 75.6 69.6 66.0
Leikvin 78.7 76.4 71.6 63.3 54.1
Leik 77.7 72.9 69.0 67.2 58.6
Unnur 76.6 71.6 67.9 62.7 55.8
Norcoast 79.5 76.2 72.4 66.5 58.6
Locations and varieties. Table 31 shows the digestibility of each variety at each location for
three different harvest dates (the fírst, the third and the fifth), an average of the experiment
years. The digestibility at Korpa was generally a little lower than at the other places and often
a little higher in Kollaíjörður than in Greenland and Iceland. The average temperature for May,
June and July was highest at Korpa during the experimental period so it was not unexpected
that the digestibility would be a little lower there. The lower digestibility in Greenland than in
Kollafjorður probably resulted from the fact that generally the plants in Greenland were
harvested at little later growth stages than in Kollafjorður (Table 12). This was especially true
for 1996.
The digestibility of Poa pratensis was lower than of timothy and Seida for all harvest
dates. The digestibility of Seida was as high as for timothy during the first weeks of the growth
period. The results indicate that the digestibility of Lavang was higher in early growth stages
but of Fylking in the later ones. Lavang grows faster in early spring and many of the plants
goes to the heading stage while most of the Fylking plants remain at leaf stages. No difference
in digestibility was found between Engmo and Vega.
The average decline of digestibility during the harvest period for Seida was 0.27
percentage units day'1, 0.24 for the timothy varieties, and 0.22 for the Poa pratensis varieties.
Even though the digestibility was lowest for Poa pratensis on all harvest dates, the decline
was a little slower than for the other species.