Pros And Cons Of Inbreeding Sheep

Inbreeding and sheep, you’ve heard about it and maybe even considered using inbreeding in your flock, but the question is: is inbreeding good or bad?

Well, as you may have guessed, inbreeding has advantages and disadvantages, both of which we’ll go over so you can decide if inbreeding would work in your situation or not.

white faced ewes grazing hay in winter

Sheep inbreeding has some definites (things that will happen)

Inbreeding has some definites, meaning things that will happen.

These definites may be good or bad, depending upon how you look at the trait and what you are shooting for with your flock and your management goals for your sheep.

Can You Breed Closely Related Sheep? is my article that goes further into reasons for inbreeding and times when you should use a different breeding system.

Inbreeding is one of many tools that a breeder (of sheep or any other livestock) has available.

The results are always a trade off, which to add further complication will also be combined with seasonal variabilities and management shortfalls, if there are any.

Inbreeding is a long term game, it depends upon keeping same outlook and goal over generations of sheep and culling ones that don’t make the cut.

Inbreeding sheep has some advantages

Inbreeding sheep has some advantages. Most folks would consider these things to be positive, but not all things are good to all flocks or at the very least are not the main priority of the flock owner at the time.

The main advantages of inbreeding are:

  • concentration of traits
  • brings out hidden genetics
  • makes sheep more genetically similar
  • can be used at any scale
  • can be used on any farm

Concentration of traits

Inbreeding concentrates traits, it makes the trait that you most associate with a specific breed of sheep show up in those sheep and not other breeds.

This is why you look at a Suffolk and can tell that it is a Suffolk with just a glance, you don’t have to ponder if it is a Dorset or a Texel, you can clearly see breed characteristics that make it a Suffolk.

Other breeds have done this same thing, just with different traits and for different results. All of this is accomplished through years of inbreeding.

Inbreeding is essential to the development of prepotent animals — animals that uniformly “stamp” their characteristics on their progeny. 

Sheep 201: Breeding Systems

For instance, this is why you can tell a lamb that is sired by a Cheviot ram, even if the ram is a crossbred, the characteristics of Cheviot genes shine through.

This is because what makes a Cheviot a Cheviot has been stamped into the breed over years of selection.

I see the Cheviot influence most easily in the head and ears, but you can also see it in body conformation of lambs. That is a legacy of very selective breeding and concentration of traits.

one black ewe in flock of white faced ewes
Notice the black sheep? She is a surprise result of some of our genetics, since all the rest of our sheep, including her parents, are white. I get a kick out of her, love working with her fleece and, on a more practical note, she does a great job, so she stays in the flock as a commercial ewe.

Brings out hidden genetics

When you concentrated genetics, you also increase the likelihood that undesirable genetics will show up.

While this may seem like a negative result, it is actually a positive outcome since no hidden genes or recessive traits will remain after a few generations of inbreeding.

Once you find the recessive genes that are lurking in your flock, now you can eliminate them and carry on with your breeding program being fairly sure that no other genetic surprises are going to pop up.

Makes sheep more genetically similar

Inbreeding makes the sheep you have more genetically similar than most sheep of that breed.

This means that you are developing specialists that are well selected for whatever traits you are concentrating in your inbreeding program.

Is It Okay To Inbreed Sheep? is my article that goes more into figuring out if your flock would benefit from inbreeding or use another breeding plan.

Can be used at any scale

Inbreeding can be used in part but not all of your flock. This would require multiple rams and more management, including running mini flocks for at least the breeding season but it is an option.

For example, you could inbreed one set of sheep for a sire line, but not inbreed the flock as a whole. This means you would have two separate lines (families of sheep) with one line inbred and one line not inbred.

This would be more work on your part, but it would give you a way to keep the genetics tight on a select few breedings, like to produce a ram, but keep the genetics spread further out for the rest of the flock.

Can be used on any farm

Another advantage of inbreeding sheep is that you can use this approach to genetic improvement on any farm, it is not limited to those with large numbers or technical advantages.

Regular folks with a plan that they stick to can successfully use inbreeding to improve the flock.

Inbreeding has some disadvantages

Inbreeding has some disadvantages. These may be things that the flock owner is willing to deal with or have happen in order to get a higher priority result

The main disadvantages of inbreeding are:

  • forces recessive genes to surface
  • can turn out poorly
  • lowers performance of flock
  • must keep singular focus over years
  • requires higher levels of planning and management

Forces recessive genes to surface

In many flocks, crossbreeding (using a ram of a different breed than the ewes) or at the very least getting a ram from another flock, rather than keeping your own, is that you dilute out recessive traits.

With inbreeding you are doing exactly the opposite, you are working to surface these traits, which means things you would normally not see will show up more frequently than if you were not inbreeding.

This is one of those things most folks would consider to be a negative, but for the purebred breeder, I consider this to be a positive. I’d want these genetics found and rooted out of my stock.

Can turn out poorly

It is possible that you will not like the results of the concentration of traits, since it will surface some recessive traits that result in poor performance or increased mortality.

The catch here is this is one of those you don’t know until you try it kind of things. When will the negatives show up? You don’t know. What will that negative be? You don’t know that either.

For anyone who needs their stock to perform for income’s sake, inbreeding may have too high of a financial risk, since you do not know what you’ll get until you have it and by then you are stuck.

How Do You Keep Sheep From Inbreeding? is my article that will give you some tips to reduce the chances of inbreeding in your flock.

Lowers performance of flock

Inbreeding will lower the performance of the flock, especially when compared to farms that are using rams from other breeds to take advantage of hybrid vigor.

In general, inbreeding results in an overall lowering in performance: vigor, disease resistance, reproductive efficiency, and survivability.

Sheep 201: Breeding Systems

This is commonly called inbreeding depression, which I consider to be the opposite of hybrid vigor.

Must keep singular focus over years

Inbreeding takes focus and consistency, over a period of years. For many folks this is more effort than they are willing to put into their breeding plan.

For inbreeding to be successful, you must choose a specific direction and stick to it for generations of your sheep.

Since sheep can reproduce once per year (some every 8 months) your results are slow to show up and changes in genetics take more time than if you were working with something that reproduced faster.

You also have to stick to your plan, even when you have doubts. Breeding stock is not a game for folks who want a quick result or who are easily discouraged.

Requires high levels of planning and management

Inbreeding requires a higher level of planning and management from you the flock owner and manager than most other breeding plans require.

You have to go into breeding season with a very specific goal in mind and have the specific animals selected to use to further that goal.

This probably means more than work than normal for you.

You will also have to have a clear set of things that you are looking for and a specific way to determine if you are getting those results.

For instance, if you are going for a shorter style of sheep, how are you determining shorter? If that sounds dumb, you are not fully thinking this through.

Do you mean that you are measuring at hip height at one year of age?

Are you wanting to reduce leg length but keep the body size the same as it is now?

Do you want the sheep to be thinner built and shorter or keep the same build as now and just be two inches shorter?

You must have a clear idea of exactly what you are looking for and what you are using to determine if your results are headed in the direction you want.

Additional resources:

Science Direct has an article on Inbreeding trends and genetic diversity in purebred sheep which shows data on the percent inbreeding in some common sheep breeds

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