What is a Composite Breed?

Composite sheep; photo courtesy of USDA ARS

Composite breeds are growing in popularity across the United States. This trend seems to be the most advanced among beef cattle producers, but has gained some attention among sheep and goat breeders, as well.

In the development phase, creating a composite breed involves crossing two or more pure breeds until a desired ratio is achieved. This may sound simple, but to create a sizable population free from inbreeding problems requires dozens of sires and potentially hundreds of females. The crossbred offspring of this initial foundation have to be crossed and preferably recrossed until the population stabilizes with each breed contributing to the overall genetic makeup in the desired proportion.

Once the composite breed is established, however, management becomes extremely simple. A composite is mated like a pure breed. In other words, composite animals can be freely bred to each other without concern about losing consistency. Also, only one breeding group is required, unlike long-term crossbreeding systems that maximize hybrid vigor through the maintenance of several herds, each of a different breed or cross thereof.

As you might have noticed, a true composite breed is essentially a pure breed in its infancy.

A few populations are referred to as composites or “open” composites, but are maintained with regular influxes of new genetics from other breeds. While this guarantees that inbreeding will be avoided entirely, it once again adds an element of inconsistency into the population. Open composites tend to fluctuate wildly in performance unless managed carefully and deliberately.

 

Examples of Composite Breeds

There are many different composite breeds available in the beef cattle world today. Examples include:

  • Balancer.
  • Beefmaster.
  • Brangus.
  • Braford.
  • LimFlex.
  • MARC II.
  • Santa Gertrudis.

In sheep, one of the most common composites is the Polypay, designed to excel in both lamb and wool production. Goat keepers can take advantage of the TexMaster, a meat breed.

 

Why Use Composite Breeds?

There are several reasons people might opt to use a composite breed or sire:

  • Predictability.
  • Consistent levels of hybrid vigor—very difficult to maintain in both long-term purebreeding and crossbreeding programs.
  • The ability to combine desired traits of several pure breeds, thus quickly creating an animal population ideally suited to a given set of environmental or economic circumstances.
  • Ease of management; other types of crossbreeding rotations can become painfully complicated, particularly where the land base limits the number of separate herds or flocks that can be maintained.

 

Disadvantages of Composite Breeds

Composite breeds have one major disadvantage compared to crossbred animals, and that is a somewhat lower level of hybrid vigor. However, this is only a problem in the short term. Hybrid vigor is maximized in the first generation of a cross, or when the crossbred population is initially created. It is lost in subsequent generations (see the explanation in The Breeding Toolbox series). Complex rotational crossbreeding systems can be created to maximize hybrid vigor over time, but taking advantage of a composite breed is much easier. Of course, where young animals are raised solely for production and not for breeding purposes, crossbreeding may be considered as a way to maximize immediate levels of hybrid vigor.

Care must be taken to avoid high levels of inbreeding, even when raising composite livestock. If replacement breeding animals are raised within the herd, inbreeding is a real threat, particularly in a small operation. This problem can be avoided by periodically introducing a new sire of the same composite breed.

And, of course, it must be remembered that no composite breed is a silver bullet. If inferior animals go into the gene pool of the composite population, inferior animals will likely be the result. Composite breeding is not an excuse to avoid selection and culling of breeding stock.

But for those seeking a balance between consistency and hybrid vigor and those who cannot otherwise find the best genetics for their situation, a well-bred composite may be the answer.

Posted by hsotr