Íslenskar landbúnaðarrannsóknir - 01.09.1976, Page 56

ÍSL. LANDBÚN.
j. agr. res. icel. 1976 8, 1-2: 54-58
Studies on autumn weight of Icelandic lambs
II. Heritability estimates
JÓN VlÐAR JÓNMUNDSSON
Agricultural Research Institute,
Reykjavík, Iceland.
ABSTRACT
The paper describes the estimation of the heritability of autumn weight of lambs by half-sib ana-
lysis. The heritability for '6326 male lambs was found to be 0.19 * 0.03 and that for 6645
female lambs as 0.29 — 0.04.
The heritability of maternal effect on autumn weight of lambs was also calculated, yielding an
estimate of 0.27 — 0.04 equal for both sexes. Possible sources of bias in the obtained estimates
are compared with comparable values in the lit-erature.
Introduction.
The heritability of a character is one of the
fundamental parameters in the preparation
of effective breeding plans. In order to be
able to calculate estimated genetic gain from
selection, the heritability of the character in
question must also be known. The present
investigation was therefore undertaken in
order to estimate the heritability of autumn
weight of lambs and the heritability of ma-
ternal effects on the autumn weight of lambs.
Material.
The data used in the present study have been
described in a previous paper in this series
(Jónmundsson 1976). The autumn weight
of individual lambs were corrected using the
additive correction factors describer (JÓN-
mundsson 1976). Information on sire of
dam was missing in the data from 1968. The
heritability of maternal effect on autumn
weight of lambs is therefore based on data
from 5 years.
Methods.
a. Autumn weight of lambs.
The heritability calculations were based on
half-sib correlation and the analysis carried
out within year, farm and sex of lamb. The
following analysis of variance, as described
by Turner and Young (1969) was used.