Íslenskar landbúnaðarrannsóknir - 01.03.1970, Blaðsíða 38

36 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
The genotyping was based on the as-
sumption that the colours could be ex-
plained in terms of genes at the three loci,
A, B and S, as describecl previously, p. 26.
For genotyping individual ewes their
own colour was the first criterion. White
ewes were always assumed to carry A1( and
if they came from white parents and had
never given any nonwhite progeny they
could not be genotyped any further. Their
genotype was then written as 1.........,
where the dots represent unknown genes.
During punching, only the first of the 6
columns in the card reserved for the geno-
type was punched and the others left
blank.
II a wliite ewe was known to be the
daughter of a black sire, her genotype was
punched as 15 ...., if nothing was known
about the sire’s genotype with respect to
brown colour and white markings, and if
no further information about the ewe’s
genotype could be obtained from her own
progeny. For a white ewe out of a white
dam and a brown sire with white mark-
ings the genotype was punched as 15.2.2.
the blanks representing the unknown genes
at loci B and S, which she had received
from the dam. If the tliird lamb of a ewe
of this parentage had a brown sire with
white markings and was black without
white markings, this lamb woulcl be taken
as a proof that the ewe was of the geno-
type A^AgB^B^S^So, which was then
punched as 151212. This would then be
punched as her genotype in all cards carry-
ing records made one year after this dis-
covery and later. For records made up to
and including the discovery of the previ-
ously unknown genes, the same genotype
would also be punched in the cards, but
an X (11-punch) would be punched above
the newly discoverecl genes iu all cards up
to and including the year of discovery.
l’he first three cards for the ewe in the
above example would then have had the
X X
genotypes punched as 151212 (or 15J2J2)>
while in all subsequent cards the genotype
would be punched as 151212.
The above distinction between genes
known prior to and subsequent to a parti-
cular mating was made in order to use in-
formation after the particular mating as a
mating of a known genotype. Matings
prior to the discovery were on the other
hand sometimes used in connection with
genotyping of rams.
When tlie ewes had been genotyped and
all necessary non-numerical information cod-
ed the data were punched and the punched
cards checked as described previously.
During the punching, no information
about the genotype of the ram was punch-
ed into the cards. After the punching was
completed, liowever, the cards were sorted
on main colour of lamb, genotype of dam,
year of record and ram number, and only
one locus of genotype of dam was taken
into account at a time.
After the first sorting, the cards were
available in order according to ram, year
on record sorted within each ram, geno-
type of ewe at the A-locus sorted within
year with zone punching in genotype sup-
pressed, and colour of lambs sorted within
genotype of ewe.
The cards were now run through a
tabulator and counts made for lambs of
each colour within genotype of ewe, record
year and ram number. From these tables
and from the colour of the sire and the
information about the colour of his par-
ents, his genotype at locus A was deter-
mined. When all rariis had thus been geno-
typed with respect to the A-locus, the cards
were again sorted in a similar way, but
now with respect to the B-locus,! and fin-
ally for the S-locus. When rams were geno-
typed with respect to the S-locus, the cards
were sorted on 3rd and 4th digit of lamb
colour, and not on main colour.