Íslenskar landbúnaðarrannsóknir - 01.03.1970, Blaðsíða 49

COLOUR INHERITANCE IN ICELANDIC SHEEP 47
eitlier the A^-allele or A2-allele by muta-
tion to A5.
Case 13. Mating A5A5 X AjAg.
One greybrown lamb.
The lamb was born on the Experimental
Farm Hestur. Date of mating 3/1/1957,
date of lambing unknown. Twins, white
female and greybrown male.
The sire was No. 01055, brown, assunted
genotype AgAgBoBj.S^S^. He was the son
of white parents, sire No. 01010, genotype
A4A5— B2-----and dam No. 25017 on farm
25, assumed genotype AtA5— B2---. Ram
No. 01055 was bought to the Experimental
Farm in autumn 1956 and was classified
as brown then, 4—5 months old.
The dam of the grevbrown lamb, No.
01232, genotype A4A5— B2-----, gave al-
together 4 nonwhite lambs, none of them
showing the A2-allele, when mated to
white heterozygous sires and nonwhite sires
which did not carry the A2-allele.
Ram No. 01055 on the other hand gave
another greybrown lamb where the A2-
allele was not present in the dam, see
case 16.
Case 14. Mating A5A5 X A2A4.
One grey mouflon lamb.
The larnb was born on farm No. 4. Date
of mating 31/12/1960, date of lambing
19/5/1961. One lamb, a grey mouflon fe-
male.
The sire was No. 04030, black, genotype
A5A5B1B1S1S1, and the dam No. 04045,
grey mouflon, assumed genotype A2A4Bt
— S4—. As information is not available
on the colour of the parents of ewe No.
04045 she could eventually have been of
genotype A2A6 or A6A5. The lamb in
question could also have been sired by a
homozygous grey ram used on the farm in
the same year. This case must therefore
be left open to doubt.
Case 15. Mating A5A5 X A2A5.
Two white lambs.
One of the lambs was born on farm No.
10 in 1960. Date of mating and date of
lambing unknown. One lamb, a white
male.
The sire was No. 10002, brown, geno-
type AgAjBoBoS-^So. The dam was No.
10011, grey, genotype A2A5B4— S4— . No
information is available on her parents.
The other lamb was born on farm No.
14. Date of mating 2/1/1960, date of lamb-
ing 26/5/1960. One lantb, a white female.
The sire of this lamb was ram No.
14061, black with white markings, geno-
type A5A5B4—S2S2. The dam was ewe
No. 14122, grey genotype A2A5B4— S4S2.
Both the above cases could well have
been due to faulty records of parentage,
and the larnbs could have been the pro-
geny of any of many white sires used on
these two farms in 1960.
Case 16. Mating A5A5 X A3A5.
One greybrown lamb.
Tlie lamb was born on the Experimental
Farm Hestur. Date of mating 28/12/1956,
date of lambing 23/5/1957. One lamb, a
greybrown male.
The sire of the lamb was No. 01055,
see case 13.
The dam was ewe No. 01367, black
badgerface with white markings, genotype
A3A5Bj B2S2S2.
Ewe No. 01367 gave altogether 7 non-
white larnbs, other than the one above,
which could not have obtained the A2-
allele from their sire. None of these lambs
showed the A2-allele, so it seems com-
pletely justified to ascribe the unexpected
colour to a deviation from norrnal in the
sire of those two lambs.
As mentioned before this ram was de-