This site has one of the best explanations:
http://www.lionhead.us/talk_lionhead.htm
When a baby is born I don't usually know for sure what type of mane ithas - but I can generally tell. If a baby is double maned -it will be shiny on the hindquarters...where the skirting will come inlater.
As the baby gets its hair, the flanks of a double mane baby will stayfurless for a bit longer. Here is an example of a double manebaby at a young age - but old enough to have its eyes opened andstuff...
Can you see how it looks funny in the flank or skirting area? This isbecause it is going to get mane or wool there. If this babywas a single mane baby - it would have normal fur there like any otherbaby does at that age.
It really is only possible to tell for sure the double mane rabbitsfrom the single mane rabbits at birth and shortly afterwards unless youare a very experienced breeder. I have breeder friends whocan tell at a glance whether a rabbit is double maned or singlemaned...me? Well - I have to look at it a bit and study it(unless I raised it at our place).
Some of you may remember Shopgirl (originally called"Meathead"). Here is here photo as an adult...she is singlemaned.
Now here is a double mane adult at a slightly older age:
Shopgirl's photo doesn't show it well - she does have some mane underher chin - not much - and she has tuftsof mane at her ears -not the big wool look.
So how do rabbits get single mane or double mane genes? it's pretty easy to figure out...sort of.
The baby takes the mane gene from each parent. If ababyhas two parents that are double-maned, thenthebaby will be double maned. If the baby has one parent who issingle maned and one who is double maned...then the baby has a 50%chance of being single maned and a 50% chance of being doublemaned. It just depends upon whichgene it gets fromthe single mane parent..the mane gene or the no-mane gene.
Let's make it more complicated...you have two single mane lionheads andmate them. Well...if I remember right - 50% of the litterwill be double maned, 25% will be single maned and 25% will be"no-maned" and lookjust like other rabbits.
Some breeders still are doing hybrids where they will mate a lionheadwith a rabbit of another breed...usuallyNetherland dwarf -but it could be something else. In that case, thenon-lionhead is considered a "no mane". The baby will not geta mane genefrom that parent (obviously). However,it will geta mane gene from the maned parent IF the parent isdouble maned (for sure) - and it *might* get a mane gene from thelionhead if it is a single maned lionhead.
So basically - when you're looking for a lionhead - you will usuallywant to find a double mane lionhead that is from a line that is knownfor keeping their manes. I do have asingle manelionhead that still has his mane (Harry) and he'salmost 2years old now. Everytime he molts - it comes innicer. He is Shopgirl's dad and her mane may stay because ofthat. I am still watching and waiting to see.
I hope this helps in some way.
By the way - some of the top breeders do work with singlemanes. Why? Because they find if they take a singlemane to a double mane - they get longer manes from theiroffspring. I don't know the exact way that they do it - likehow oftenor how many generations between using a singlemane. But from what I've heard - using double manes only can"stunt" the mane length although it does make it nice and dense...sobringing in a single mane into the line every once in a while helps toget that mane to grow long.
I haven't played around with their theory yet.
Peg