[Jacob-list] 2/4 Horn Heritability

[Jacobflock at aol.com]

G L Alderson (1992) reported on the inheritance of two and four horns for 
Jacob, Manx Loughtan and Henrideans.  He concluded neither was dominant.  
When 4 horns were matyed, some 2 horns appear; 4 horns appear from mated 2 
horns.

Alderson suggested that there are two loci (chromosome 10) and allele A is 
dominat to a at the first locus; B is dominant to b at the second.  Animals 
that are A or AA and B- or BB are two horned.  Four horned are aa or bb or 
both.  He then goes on to show how actaul breeding results support the two 
loci and concludes...the inheritance is apparently complicated.  There may be 
a basis for his pattern; it seems to be proven by breeder results, that true 
genotype breeding always produces horns.

You have had your disappointment with the "good looking" father that produced 
the horny "toad".  Don't give up.  Look at the family tree.  Find pictures of 
sires and dams as far back as you can.  We used to buy sheep looking at a 
picture of the "sheep" and looking at names on a pedigree.  Now we find 
ourselves looking at names on the pedigree, calculating inbreeding 
coefficients, looking for pictures of sires and dams.  There is fun pleasing 
the sense of eye looking at phenotype issues...its the genetics you really 
want to look at.  We are all still trying to learn.

We recently bred Thor (outstanding horns etc) to several four horned 
ewes...the lambs were all four horned....and all had FORWARD horns like 
Thor's MOTHER.  And still learning not to try to beat the genetic odds.