Line breeding

[AllForage]

L1 has always been the selection of yearling weight I believe and still is.

http://www.ars.usda.gov/is/ar/archive/a ... 6.htm?pf=1

 

[backhoeboogie]

Knersie thank you, makes it more understanding.

bc too. It is always good when someone in the know takes the time.

 

[chipsahoy]

ZMT,

I'll try to simplify it as much as possible...

Firstly you need an outstanding individual that approximates your ideal, usually it will be a well proven sire.
You mate him to cows that will address weaknesses the sire might have (the more uniform the cows the faster the results)
You continue breeding this same sire to the same cows for as long as he is available.
The resulting calves will be halfsibs.
You use the best of the halfsib bulls and breed it to his halfsib heifers with the hope to produce a better bull than himself or his sire. Once you find a good linebred bull continue to use him on his relatives until he outbreeds himself and give you yet a better bull prospect.
The ideal is to concentrate the already good traits of the original sire by keeping his 50% influence consistant through halfsib matings.
Don't exceed that 50% influence if you can help it, as 50% is the natural relationship an offspring has of each parent.

The crux of the matter is to cull hard, use only the best bull calf and don't keep any heifers with faults or undesireable traits. Remember you'll eventually get everything that you've specifically selected for AND THAT YOU DIDN'T SPECIFICALLY SELECTED AGAINST!

The good thing is you can still sell your culls at market value making the risk much smaller as is the popular believe.

When you say that the bull is continued to be bred to his Relatives? Do you breed him to relatives other than his half sisters? If you do, How do you keep track of the percentage of blood of the original sire?

I guess the answer to the above question might answer this one too, but when you say that the bull's blood is concentrated by half sib matings, is that only in the beginning, as you explained in your post? or is it a long term mating, I mean every generation you simply mate 1/2 siblings together? I mean If I took a two year old bull and mated him to the 4 year old cows then then would still be 50% of the original sire but not as closely bred if they had different Dames right?

 

[igrowgrass]

I want to share this with all of you, because some people don't understand how genetics work on a basic level.

Inbreeding, in and of itself, has no ill effect on cattle.

Your cattle have a pool of genes. These are all the traits that are floating around inside the DNA. Some are dominant, some are recessive, some are co-dominant, some are other weird things. But basically, the pool contains all of the possible traits that your animal could pass on to its offspring.

When you breed two animals together that are not related the pool of genes is vast and the bad genes are spread out all over the place. The chance of the bad genes, like infertility, lameness, etc popping up are very low.

When you selectively breed your cattle for performance you are working hard to get all of the bad genes out of the pool.

Scientifically, if you could get all of the bad genes out of the pool and you only had good genes for the cattle to pass on to their offspring you could breed brother and sister forever and ever with no ill effects.

Thus, if you work hard, cull hard, and don't breed animals with any visible deficiencies you are strengthening and cleaning your gene pool.

The cleaner the gene pool is, the less that in breeding will effect the quality of your cattle.

In fact, if you have REEEEEEEEALLY high quality animals, line breeding or in breeding will actually help to "lock in" certain desirable traits.

I think that people are geared to believe that all in breeding is bad. It isn't. Its only bad when the gene pool is dirty.

I used to breed rats as a hobby. I owned pythons and started raising rats to feed them. Then I started breeding rats to sell to other people. Before you know it I was selling thousands of them per month. It became a business. They are mature at 16 weeks, and gestation is only around 23 days. You can go through so many generations so quickly that you can really see how all of this plays out. I have lines of rats that you can breed brother and sister and they will produce 10-12 identical offspring where all will be healthy and perfect. Its a matter of cleaning the gene pool before you start in breeding.