Inbreeding coefficient and what is acceptable?

[Casey76]

So I'm starting to do some preliminary investigations into finding a suitable stallion for Tartine.

Have a slight problem in that as Mérens are a rare breed, there are currently only 75 approved stallions, and as this number is actually increased over previous years (the breed was almost wiped out in the 70s) most horses are related to one another at one level.

E.g. Tartine has an inbreeding coefficient of 2.8% (as specified by the Haras Nationaux), she has two stallions (Constantaire, 1968 and Tailleur, 1963) in her pedigree on both sides, but both 4 generations ago.

The other slight problem is that due to lack of approved stallions, the current active stallions have a lot (relative) of progeny, which is actually concentrating the gene pool, not expanding it.

It's at times like this when I have a passing regret for gelding Blitz, as he has a rare line on the dam side.

I know everyone will have their own opinion, however how close is too close? What should I be looking for along with conformation, temprement, compatibility with my mare...

Thanks

 

[Alec Swan]

I suspect that it would need a geneticist to answer your question clearly. I have a working bred gundog here, and she has a B/COi of 34%. From what I can see of it, the only thing that such line-in-close breeding (call it what you will) does is that it reduces the size of the animals in question, and in the case of dogs it reduces litter sizes, so possibly in horses it may restrict the ability to conceive or to promote the breed. Such genetically close breeding may very well inhibit an animal's ability to withstand disease.

I know of a very well known and highly successful breeder who will tell you that the theoretical reliance upon Breeding Coefficients, is a complete and utter load of old toffee. He's a highly successful man, and his opinions shouldn't be discarded.

Me? Dunno, but it sounds as though you will have little choice!

Alec.

 

[Dry Rot]

It is not so much the breeding system but the selection of your breeding stock. Whatever stallion (and mare!) you choose, you should be absolutely ruthless in your examination of him both physically and mentally. There are plenty of examples of successful inbreeding, mostly when Nature has a big part in the selection. One authority suggests that a breeder should attempt to follow Nature and ruthlessly select as Nature would do. The problems arise when humans become emotionally involved and start selecting stock for all the wrong reasons.

On example of successful inbreeding is the Chillingham wild cattle (have a Google) which are said to have been kept within a walled enclosure for 600 years and were left to breed without interference by man. Another is the rabbits in Australia (and there are quite a few of them now!) which are all said to be descended from a few dozen pairs! On the other hand, have a look at the video "Pedigree Dogs Exposed" for what bad selection for fancy points for the show bench can do.

I wouldn't say inbreeding coefficients are a load of rubbish but they can tell a completely false story. Really, the only way to inbreed successfully is from the knowledge gained from experience. That's when you find out one lifetime is not enough. The only way to tell if close is too close is to try it. But is that politically acceptable today? That is for you to decide.

 

[Rollin]

We have in place a SPARKS programme for the Cleveland Bay.

Developed from work done in Zoo's who are dealing with endangered species, the programme looks at the relationship between ALL of our Cleveland Bays and (some of us) aim to produce foals which will help reduce in breeding and widen the gene pool - this does not necessarily mean seeking the rarest stallion for our mares. I always aim to produce foals with lower mean kinship than their parents - if possible.

The expert on this is Dr. Andy Dell who was given an award by the RBST for his work.

I will pm you his email address - he may be able to guide you.

I take my hat off the the French National Stud they have done some wonderful work in preserving the Merens.

 

[no_no_nanette]

We came across Merens horses about twenty years ago when we were staying in the Pyrenees at a B&B where they bred Merens and Newfoundland dogs. I'd never heard of this breed before, but thought that they were lovely, and seemed to make excellent riding horses. So pleased to hear that the French National Stud are putting a lot of effort into saving the breed - and good luck with your breeding programme!

 

[Alec Swan]

.......

On example of successful inbreeding is the Chillingham wild cattle (have a Google) which are said to have been kept within a walled enclosure for 600 years and were left to breed without interference by man. ........

That's interesting, as I've just googled them, as you suggested, and it seems that the adult cattle are around the 300kg mark, which is very small. There's a park of white Fallow Deer at Thetford, and the adult's weigh about two thirds of the weight that one would expect. The Deer, like the cattle, have been inbred without any fresh introductions, for many generations (since WW11 or before, I suspect), and with predictable results. The buck's "Heads" are also exceptionally weedy, with adults having the appearance of beasts which have cast only once. Were they mine, I'd shoot the lot, and bring in some decent Reds!!

Alec.