Íslenskar landbúnaðarrannsóknir - 01.03.1977, Page 22

20 ÍSLENZKAR LANDBÚNABARRANNSÓKNIR
Table 5. Effect of the different factors in the model.
Variable in the model
Age of lamb 5,31
Sex 8,02
Age of dam 1,73
Type of birth and rearing 25,45
TYPE OF BIRTH AND REARING
The type of birth and rearing were combined
in one classification in the model. The type
of rearing is recorded when the lambs arrive
from the mountain grazing in the autumn.
Lambs of type 3X2 and 3X1 are taken as
one group. Only 23 lambs in the whóle
material were triplets at birth and singles in
the autumn.
Constants for the effects of type of birth
and rearing are presented in table 6. The
difference in weaning weight between twins
and singles is 6.35 kg. Hallgrímsson
(1971) found this difference to be 6.4 kg
Table 6 . Constants for the effect of type of birth and rearing on
weaning weight, carcass weight and dressing percentage.
Type of birth and rearing Weaning weight Caröaás weight Dressing percentage
1X1- 4,83 0,08 2,61 0,04 1,54 0,06
2X2 -1,52 0,07 -0,91 0,04 -0,64 0,05
3X3 -3,33 0,23 -1,73 0,12 -1,02 0,16
2X1 2,19 0,10 1,19 0,05 0,72 0,07
3X2 3X1} -2,16 0,18 -1,15 0,10 -0,61 0,13