inbreeding?

[Tilly]

As I've been looking at possible bulls to breed my dexter heifer to, I've noticed a lot of daughter to sire and Half brother to sister breedings. As you may have noticed from other post I've penned, I don't even have my feet wet yet, just a big toe!!! So is this a common practice, and how closely related can they be ideally? We just had a beautiful dun bull calf born, and if he turns out anything like his pappa, we would like to keep him a bull for ourselves, but he is a half brother to my heifer who is picked to be my replacement milk cow. Is this a conflict of breeding?

[Karin L]

IMO, with inbreeding you gotta have TOP notch stock AND you gotta know every detail, genetic-wise, physical traits-wise, etc. to even accomplish inbreeding.

So if I were you, the way you say you don't have much experience, I wouldn't even think about doing any inbreeding in your herd, because you never know what kinda stuff (and I mean BAD stuff) you could get yourself into.

JMHO.

[genebo]

It's sort of like a bell curve. You're going to get some average calves and some on both sides of average. The bad ones have to be culled (hamburger). That means heifers and bulls.

When you just have one cow to breed, it doesn't seem worth it to gamble. I know you might get that exceptional calf, but could you stand it if you got a really substandard one?

Father to daughter is not as close as brother to sister. The daughter has exactly 1/2 of the father's genes, but brothers and sisters have the potential to have all of their genes identical. Identical pairs of genes are what unleashes recessive traits.

Genebo
Paradise Farm

[Ralph in N.E.Oh]

Great answer Genebo

I would think that AI would be a much better choice that keeping a bull for one cow. There are some awesome Dexter AI bulls out there. I'd breed for perfection. Semen is cheap when compared to keeping a bull.

[Tilly]

Thanks, after posting I did the reality check of keeping a bull. We want to eventually, but that time is not here yet. I've checked hoffmans on AI semen . Any other ideas? I'm looking to keep smaller dexters, My older cow that had the calf is very beefy, the heifer is also, but they have good milking lines behind them. Looking for a smaller bull I think for AI.

[ArmyDoc]

Your question about inbreeding - if it is common and if it is a good idea is an excellent one. Yes, it is common. Is it a good idea? That's more controversial.

In breeding increases the likelihood that a given animal will receive the same gene from both parents, resulting in it's being homozygous for that trait. This can be either good or bad, depending on the specific trait you are looking at. If the trait is a positive one - say having the hair color you want, it is a good thing. If you breed two individuals that are homozygous for the same trait, 100% of their offspring will also have that trait. If that trait is dominant, 100% of the offspring will have that trait, even if only one of the parents is homozygous for th trait.

But what if the trait is not positve? What if the gene is for hemophilia, or to pick a negative trait specific to Dexter Cattle, the gene for achondroplasia? In this case, inbreeding would increasing the likelihood of having a negative characteristic.

The amount of inbreeding can be calculated by analysing the pedigree of an animal. The more generations you have recorded, the more accurate the calculation. You can do it by hand, but the easiest way is to use a program to do it. One good program is Pedigree Viewer, by Brian Kinghorn. Best of all it's free! Here's his website if you're interested:

http://www-personal.une.edu.au/~bkinghor/

There are several sites where you can learn more about inbreeding / linebreeding etc. Here are a couple to get you started:

http://members.tripod.com/~Marge_S_2...inbreeding.htm

http://www.genecarrhorseranch.com/line_breeding.php

Bottom line, Inbreeding can be a powerful tool used to strengthen or improve a line and make it breed true. Unfortunately, I don't think this is very often the result. I think the most common reason for inbreeding is probably ignorance. Most people aren't trying to do something harmful, in fact most people are probably trying to do something good. But breeding is a science that does take some time an effort to really understand. A lot of people dont take the time to do that.

The best advice I can give you is to read, read, read and read some more. If at all possible, find an experienced breeder and have them mentor you and to learn and know your breed.



Best advice I can think of

[Tilly]

Thanks ArmyDoc, tried googling inbreeding cattle, that was fun!! Maybe I should try Linebreeding on google! Actually, this all sounds waaaaay over my head ,for now at least.

[Terry W]

Originally Posted by Tilly

Thanks ArmyDoc, tried googling inbreeding cattle, that was fun!! Maybe I should try Linebreeding on google! Actually, this all sounds waaaaay over my head ,for now at least.

No, it is not way over your head. Understanding the basics of genetics and the transmission of specific genes just takes a little getting used to. Most people tend to think in simple Mendalian terms, and that is not true for animal genetics. The Punnett Square is often used to determine the probability of a trait showing up, but Nature does not work in perfect statistical averages with every breeding--and when dealing with animals that only have one or two offspring at a time, chances are pretty good that you WON'T get what you want.

ArmyDoc--
I loved that Brian Kinghorn site, and am sending it to my BB Consortium and a genetics professor at my Alma Mater. I may even use it to help plan some breeding of my AmChins. A very nice way to puzzle out the breeding plans!!!

[genebo]

The programs and statistics of probability about cattle breeding depend upon a source of knowledge about the ancestors of the cattle you're breeding. In other words, a pedigree that reaches back for generations. After a few generations of cross-breeding, you can throw all the figures away. They don't work any more.

Genebo
Paradise Farm