Cross into profit. Charolais.

Why Crossbreed?

There are a number of advantages in crossbreeding that have driven its uptake to the point where it has been estimated that the majority of the 28 million cattle produced in Australia are crossbred animals.

The most significant reason to crossbreed is to take advantage of the natural phenomenon known as Heterosis, or Hybrid Vigour.

Heterosis

Heterosis or (Hybrid Vigour)is defined as the difference in an animals performance to that of the average of the parental breeds. The CRC (Cooperative Research Centre) for Beef calculates Heterosis as follows:

[      (Average crossbred progeny - Average of parents)     ]       x 100
                                    Average of parents

Objectives

Understanding your objectives in beef production is paramount to any successful breeding program, including crossbreeding. These objectives may include:

• Age and weight of cattle that are to be turned off,
• Type of country that the cattle will run on
• Base herd. The breed of cattle that you have now will also influence your objectives
• - Time frame for your operation.

Advantages

Some of the most widely recognised advantages of crossbreeding is that traits from different breeds can be incorporated without having to change breeds entirely.

For instance, whether you operate a predominately Brahman, Santa Gertrudis or Droughtmaster based herd in the tropics, or a Hereford, Angus or Shorthorn based herd in temperate areas, you are still able to capitalise from Heterosis without changing the breed of cattle that has performed well for you in the past.

Additionally, it has been recognised that some of the low heritable traits (those that do not respond quickly to selection pressure) such as fertility, can actually have a high response to crossbreeding (high Heterosis). This is one reason why crossbreeding in the north has become so popular.

Crossbreeding Systems

John Bertram, in his book “Breeding for Profit”, has identified five basic crossbreeding systems.

Two Breed Cross

The Two Breed Cross is used to breed F1 progeny. Usually, all progeny are sold for slaughter or other commercial producers.

This system is used mostly where the female herd is well suited to the environment and is well established. Progeny are able to benefit from the introduction of growth and carcase traits from a complementary breed such as Charolais. Heterosis is only present in the resultant progeny. F1 females can be used in a Three Breed Cross.

Three Breed Cross

While this requires the input of three breeds, F1 females can be bought in, in order to speed up the process and reduce the number of “groups” on the property.

This system allows for the occurance of heterosis in both the F1 Females, as well as the subsequent progeny. Generally, F1 females are bred to benefit from the low heritable traits such as fertility, while the addition of a third breed such as Charolais will assist growth and carcase characteristics.

A typical situation may be the use of a base Santa Gertrudis herd where Angus or Hereford are used to produce F1 females. The addition of Charolais will increase production traits.

Back Cross

Generally in a Backcross system all the male calves will be sold for slaughter while the female F1 portion are mated back to one of the parent breeds.

The advantages are full heterosis for maternal traits such as fertility and milking ability in the F1 females with improvements in carcase or growth traits forthcoming from the other parent.

A typical example of this system being used is where an upgrading program from one breed to another, such as  Charolais, occurs. By backcrossing the F1 Females to Charolais the upgrading to Charolais continues while the male progeny are slaughtered and benefit from hybrid vigour.

Rotational cross

Taking the Backcross system a step further and alternating the sires used from the original breeds (A and B) will allow both breeds to contribute strengths and weaknesses equally.

Variations witnessed in progeny in the early years may lead to difficulties and meeting specific market specifications, however as the program progresses, all progeny will benefit from hybrid vigour. More than two breeds can be used which may add to increasing the level of heterosis but may also lead to management issues when maintaining ‘groups’.

An example of successful Rotational crosses can be seen in Charolais x Braham herds to develop Charbrays.

Composite Breeding:

Examples of composites include: Santa Gertrudis, Droughtmaster, Belmont Red and Charbray.

The benefit of composites (once stabilised) is that the management requirements become similar to that for straightbreeding.

Changing market signals can be accommodated by incorporating another breed to change direction in the breeding program (and hence will return to the management criteria’s of some of the aformentioned crossbreeding programs).

The percentage of heterosis increases as more breeds contribute to the program but will not be as high as in rotational programs.

Comparing crossbreeding systems

The table below shows the maximum percentage of heterosis that can be retained from the various crossbreeding programs.

Combining selection with crossbreeding

Crossbreeding alone is no guarantee that increased production will be forthcoming. As always, genetic selection plays a vital role in improving production.

The diagram below emphasises the increased production that can be acheived when combining genetic selection with your crossbreeding program.

Source: Bertram J, et.al, “Breeding for Profit” Queensland Beef Industry Institute.

Importance of purebreds

All crossbreeding systems require the continuing input of purebred animals. Regular crossing has led to stud breeders being required to maintain and improve straightbred populations for this purpose.

More information

The information contained herein has been accessed from the Queensland Department of Primary Industry web site (www.dpi.qld.gov.au) and refers to the publication Breeding for Profit by John Bertram. Other authors of this work include: Dr Mick Carrick; Dr Dick Holroyd; Morris Lake; Warren Lehman; Kay Taylor; Rod Thompson; Dr Mick Tierney; Russell Tyler; Mick Sullivan; Rick Whittle.