Íslenskar landbúnaðarrannsóknir - 01.03.1977, Page 19

SOURCES OF VARIATION IN WEIGHTS OF LAMBS 17
Table 1. Some results from the Sheep Recordinp; Associations
in Iceland in the year 1970 and 1971.
Year Number of ewes recorded Number of lambs per 100’ ewes in the autumn' Carcass weight after ewe with
one lamb two lambs
1970 44944 141 16,8 28,5
1971 48287 145 17,5 29,9
The first Sheep Recording Associations in
Iceland were founded in 1939 but it was not
until the 1950’s that membership in the as-
sociations became common.
In 1969 data processing by electronic com-
puter was started by the Agricultural Society.
The alteration from manual handling took
place gradually and therefore most of the
data are from the year 1971. Participation
in the recording scheme was 6.65% of the
total ewe population of the country in 1970,
with an average of 60 ewes per participant.
Some results from the associations in 1970
and 1971 are summarized in table 1.
All the registration work is undertaken
by the farmer himself. The weight of the
lambs is taken when they arrive from
mountain grazing, shortly before they are
Lambing takes place in May and early
June and the lambs are slaughtered in late
September and October.
The data in the present study were obtained
from that part of the records which were
available on data cards in Icéland. The data
in the study were from 370 farm-year com-
binations. There was a great variation in the
number of lambs in each flock i. e. from 22
in the smallest to 773 in the largest flock.
The flocks are from all districts in Iceland.
In table 2 the mean and standard deviation
of the characters smdied are shown. The
variation in weaning weight of lambs within
farms is the same as that found by JÓN-
mundsson (1971) in a smdy of the varia-
tion of weaning weight of lambs on four
experimental farms in Iceland. The carcass
sent to the slaughterhouses. Table 2 . Means and standard weight deviation and dressing percentage are only (within flock) for weaning
weigjrt, carcass weight and dressing percentage.
Trait X s
Weaning weight 38,00 kg 5,12
Carcass weight 15,45 kg 2,47
Dressing percentage 40,38 % 2,65