The Accidental Smallholder Forum

Livestock => Goats => Topic started by: Dogwalker on August 25, 2019, 06:11:14 am

Title: Line breeding
Post by: Dogwalker on August 25, 2019, 06:11:14 am
I'm sorting out which goats I can send to which of my friends bucks.What are the rules, what's ok and what's not.
From things I've read don't put brothers on sisters, sons on Mum's, dad's on daughters but otherwise anything goes!
Title: Re: Line breeding
Post by: Buttermilk on August 25, 2019, 08:51:06 am
When the results are good it is line breeding and when bad it is inbreeding. 

The idea is to know what faults are in the lines and try not to breed too close to them.  So if you know a goat had a slightly out of true mouth do not put it with another, further down the line, that you know is also from a goat with a slightly wonky mouth as you are doubling up the chances of "fixing" wonky mouths in your goats.

If a goat has an exceptionally good udder and no glaring faults then I would breed closer to "fix" the good udder trait.

You stand the chance of hidden genetic traits coming out but as long as you are prepared to cull anything that inherits really bad stuff then breed as you wish.

I have often gone back to grandfather if he throws what you require.

Title: Re: Line breeding
Post by: Dogwalker on August 25, 2019, 08:56:33 am
So a buck  on his half-aunties is ok.Their Dad is his grand-dad, his mum is their half-sister.The bucks I've used till now are all champion angoras so not really any obvious faults.
Title: Re: Line breeding
Post by: cloddopper on August 25, 2019, 11:04:11 pm
So a buck  on his half-aunties is ok.Their Dad is his grand-dad, his mum is their half-sister.The bucks I've used till now are all champion angoras so not really any obvious faults.

We used to breed small mammals  as a business , I had to learn a lot about genetics and breeding .  Being small mammals we had a short  gestation period so over six or more generations we could see the effect of  in breeding to a degree.
 It might not show in their appearance or bone structure but it can  show as  early deaths , arthritic joints  mental problems , stress , and a whole host of things.

 It's good to bring in  a totally unrelated by at least seven lines  billy once in a while to revitalize the cross breed vigour as line breading and close relative breeding  tends to weaken the strain  over several generations without it initially being recognised . When you have a business where the problems show suddenly you've lost it .
 
 
Title: Re: Line breeding
Post by: Dogwalker on August 26, 2019, 07:16:40 am
A couple of the big angora breeders have recently organised importing South African embryos to revamp the national herd.  The bucks are selling for thousands, way out of my league.Some of my does will be visiting a friend's buck, just trying to learn what's a allowed and what's not.
Title: Re: Line breeding
Post by: Scarlet.Dragon on August 26, 2019, 09:27:16 pm
Interesting you list not breeding father to daughter, mother to son or brother to sister as my understanding is that all of these are acceptable but that half siblings should never be bred.  You may find the "rescue breeding" formula useful.  It takes a few read throughs to understand exactly what can and can't be done and how to create genetic diversity using female lines with a single male as a starter.  This is a link to it... http://www.critterhaven.biz/info/articles/1_ram.htm (http://www.critterhaven.biz/info/articles/1_ram.htm)

And as others have said, you need to be willing to cull anything that doesn't go well... that doesn't necessarily mean killing it, just cull it from the breeding programme.
Title: Re: Line breeding
Post by: Dogwalker on August 26, 2019, 10:04:58 pm
Thank you, (I think - I'll reread that several times at a more awake time of day)
Why would it be ok to breed full siblings and not half siblings?
Title: Re: Line breeding
Post by: roddycm on August 26, 2019, 10:40:49 pm
Thank you, (I think - I'll reread that several times at a more awake time of day)
Why would it be ok to breed full siblings and not half siblings?

My understanding from that link was half siblings is fine, what is not ok is father to daughter where they are also half siblings. ie any female from breeding son back to mother. So you wouldn't put the Male back to his sister daughter haha sounds a little disturbing!
Title: Re: Line breeding
Post by: Scarlet.Dragon on August 27, 2019, 09:58:36 am
Thank you, (I think - I'll reread that several times at a more awake time of day)
Why would it be ok to breed full siblings and not half siblings?

I've read it several times over a couple of years although I still wouldn't say I fully understand it all and I refer back to it before looking at who could be bred with whom.  I will say that a lot of what is in here has been disputed by others who promote genetic diversity over line breeding within conservation programmes.

However, from the limited knowledge I have of genetics and reading this, I believe full siblings are "OK" because theoretically (setting aside any spontaneous mutations in either of them), any progeny would be equivalent to being a full sibling to the parents... in other words the genes both parents are carrying come from the grandparents and therefore any "swaps" in genes could have come from a mating of the grandparents.

This is probably not a good explanation and is seriously oversimplified but assume that grandparents AA (male) BB (female) and CC (male) DD (female) produce kids.  The AA/BB mating gives genes AB and the CC/DD mating gives genes CD.  Mating these together gives the following potential combinations:

AB + CD = AC BC AD BD which can either be male or female.  Then assume that you have two of each of the genes one male one female so AC(m), AC(f), BC(m), BC(f), AD(m), AD(f) and BD(m), BD(f).

If you mate AC(m) to AC(f) you will get a kid with genes AC - in other words their progeny is equivalent genetically to themselves and could have resulted from a mating of the grandparents so there shouldn't be any increase in "risk" of inbreeding.  The same goes for all the other "same" combinations.

If you mate AC(m) with BD(f) you have the following options for the kids: AB, AD, CB or CD. 
AB is genetically equivalent to its grandparent AB (same for CD), AD is equivalent to its parent (same for CB/BC).  The same goes for the other "different" combinations.

If there's an undetected fault in the line then perpetually line breeding/inbreeding will bring it out, and that's when you have to cull.

Spontaneous mutations are no more likely in line breeding than they are in genetically diverse breeding and therefore you always need to be aware of faults that occur and cull that animal from the breeding programme.

Line breeding can result in stronger stock if you are starting from good strong stock to begin with or are culling hard anything that isn't healthy... this is exactly what nature does if you think about breeds like Hebrideans, Soays, Borerays etc... nature culls anything that isn't strong and the rest of the flock breeds to the strongest, fittest tup - which is undoubtedly covering its own progeny until such time as it's no longer the strongest at which point likely one of its offspring will take over... if that offspring is incompatible with a particular female line resulting in faulted breeding - nature will cull it as a weakling.

I hope this helps.  Please note, I'm not an expert, just read, and re-read multiple times as I have been looking to use this to develop genetic diversity from my own animals (foundation stock has good genetic diversity one male 4 and a half females - half being progeny of female from unrelated male) in a closed high health setup.
Title: Re: Line breeding
Post by: Dogwalker on August 27, 2019, 03:36:32 pm
AA to CC =ACfull siblings  AC to AC = AA, AC, CA or CC
AA to DD =ADso half siblings   AC to AD = AA, AD, CA or CD more diverse than full siblings.
Title: Re: Line breeding
Post by: Scarlet.Dragon on August 27, 2019, 08:24:29 pm
AA to CC =ACfull siblings  AC to AC = AA, AC, CA or CC

Yes, you're right I missed this from the explanation although AC and CA are essentially the same in the very simplified version explained and AA/CC follows the rest of the explanation I gave in relation to 'equivalent to grandparent' as the originals were AA, BB, CC and DD.  The AC or CA combination could have come from the mating of the original AA to CC and therefore equivalent to a full sibling of the parents by the grandparents. 

AA to DD =ADso half siblings   AC to AD = AA, AD, CA or CD more diverse than full siblings.

My understanding is this is the partnering to avoid if at all possible as there is a greater chance of recessive gene faults surfacing from the half siblings (i.e. it's more risky as the original genes couldn't have been produced by the generation above in that line) but as I said, I'm no expert.  I believe that if you skip a generation and then mate, these could be successful at that stage, but it's a while since I read the paper so perhaps I'm mis-remembering it.  At that point it's about only using the first generation once and then moving on to the next generation for in and out crossing to maintain the line characteristics.
Title: Re: Line breeding
Post by: Dogwalker on August 27, 2019, 08:47:02 pm
Doesn't make much sense to me that half siblings is a no-no and full siblings is ok but it's a totally academic question anyway as I wouldn't ever put any kind siblings together.I'm not trying to rescue an endangered breed or create a herd from one male. 
Thank you for an interesting article but not really the info I need.
I'm trying to work out which of my friends champion bucks can breed with my does and if I can save some stud fees by using my own buck kid on a couple of them.
Title: Re: Line breeding
Post by: Scarlet.Dragon on August 27, 2019, 10:42:36 pm
If any of yours have pedigrees in one of the recognised systems (e.g. Grassroots) you could ask for a kinship report which will tell you whether or not it's safe to breed different combinations and the coefficient against that breed's mean average if that helps?
Title: Re: Line breeding
Post by: DrMunns on September 30, 2019, 10:26:50 pm
Brian plummers book are quite good at explaining line breeding simply. He is on about dogs but the principal is the same