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One of the most powerful tools available to cattle producers to improve productivity and efficiency in a herd is the use of crossbreeding. Effective use of a crossbreeding system allows producers to take advantage of heterosis (hybrid vigour), breed complementarity, and biological breed type differences to match cattle to specific production resources (Taylor, 1984).
When considering a crossbreeding programme, it is important to understand the different systems, and what needs to be considered before attempting them. Note that failure to adequately implement a proper crossbreeding programme can potentially decrease the level of hybrid vigour observed.
Key concepts
- Crossbreeding: Mating animals of different breeds. Not to be confused with outcrossing which happens when mating unrelated animals in the same breed.
- Heterosis/hybrid vigour: The phenomenon where crossbred progeny outperform the average of their purebred parents in certain traits. Note that generally, heterosis generates the biggest improvement in lowly heritable traits.
- Breed complementarity: Using different breeds that complement each other’s strengths to produce offspring with desirable traits.
Types of crossbreeding systems
- Terminal crossbreeding: This system involves mating cows to a bull of a different breed and selling all the offspring. Replacement heifers are purchased or homebred, and the focus is on maximising hybrid vigour in the sale calves.
- Rotational crossbreeding: This system utilises two or more breeds, and replacement heifers are retained to be used in subsequent generations. Breeds are alternated with each mating, resulting in a continuous cycle of crossbreeding.
- Composite crossbreeding: This system aims to combine desirable traits from multiple breeds. Breeds are mixed to create a new breed, and the resulting composite breed is used for breeding purposes.
Crossbreeding systems range in complexity from very simple programmes such as the use of composite breeds, which are as easy as straight breeding, to elaborate rotational crossbreeding systems with four or more breeds.
A crossbreeding system should take advantage of breed complementarity and heterosis. Although the individual change in some traits is small, it has been found that lifetime production can increase by more than 20% in programmes designed to capture both individual heterosis in crossbred calves and maternal heterosis in crossbred cows (Dr Helena Theron, SA Stud Book).
The direction of crossing, or which breed sires the offspring, influences the genetic makeup and traits of the resulting calves in beef cattle, primarily through heterosis and breed complementarity. Crossbreeding between genetically diverse breeds can lead to improved performance in traits such as fertility, growth rate, and disease resistance. By strategically combining breeds, producers can leverage the strengths of different breeds to create offspring with a desirable combination of traits.
Terminal crossbreeding
Two-breed terminal systems work as follows:
- Breed A x Breed B.
- 100% individual heterosis and no maternal heterosis.
- All F1 progeny are marketed.
- F1 replacement heifers can be sold as breeding females.
- Replacement heifers are usually purchased.
- This system is particularly well-suited for operations focussed on producing weaner calves for the market.
Three-breed terminal systems work as follows:
- The most hybrid vigour of any crossbreeding scheme.
- Crossbred AB cows x Breed C sires.
- All F1 progeny are marketed.
- Purchased F1 replacement heifers should be environmentally adapted with the necessary maternal capacities.
- Terminal sires can then be selected only on growth and carcass with no attention to maternal traits.
- This system requires intensive management, including the use of artificial insemination (AI) or multiple breeding pastures.
Rotational crossbreeding
Two-breed rotational crossbreeding works as follows:
- Effective and relatively simple.
- Females sired by Breed A are mated to sires of Breed B, and females sired by Breed B are mated to sires of Breed A.
- Heterosis stabilises at 67% of potential individual and maternal heterosis after six generations.
- As replacement heifers sired by Breeds A and B are retained, both breeds should therefore have maternal characteristics.
Three- and four-breed rotational crossbreeding systems work as follows:
- Similar to the two-breed rotation with another breed added.
- Three-breed system: Breed A sires are mated to females sired by Breed B, Breed B sires are mated to females sired by Breed C, and Breed C sires are mated to females sired by Breed A.
- Hybrid vigour stabilises after several generations at 86% (three breeds) and 93% (four breeds) of potential individual and maternal hybrid vigour.
- Replacements are retained from within the herd.
- The ability to locate three or four breeds that fit a given breeding scheme can be challenging.
- For only a slight gain between three- and four-breed systems, the system becomes very complicated. Benefits may not outweigh the cost.
The three-breed roto-terminal crossbreeding system functions in the following way:
- Extension of the two-breed rotational system with a terminal sire added.
- Some cows (especially heifers) are placed in the two-breed rotation to produce replacement heifers, and the rest (older cows) are mated to a terminal sire to produce calves that are all marketed. The breeds used in the two-breed rotation must still be selected for the criteria specified in the rotational programmes.
- Terminal sires can be selected for increased growth and carcass traits to maximise production from the cowherd.
- More labour, management, and breeding pastures are needed than in a two-breed rotation.
The sire rotation crossbreeding system is characterised by the following:
- Common crossbreeding system.
- One breed of sire is used for four to six years, and then the sire breed is changed.
- This system can use two, three, or more breeds.
- A relatively high level of heterosis is maintained, usually >50% depending on the number and sequence of sires used.
Composite crossbreeding
- Has traits of economic importance from many breeds which is then maintained as a straight-bred herd.
- Has the advantage of being very easily managed once the composite breed is established (which takes many generations/years).
- It can capture a higher amount of existing genetic variation among breeds than other crossbreeding systems.
The Brahman’s contribution
The Brahman breed has significantly contributed to beef cattle crossbreeding in South Africa, particularly in developing new breeds and improving existing ones. Its ability to crossbreed with various breeds, coupled with heat tolerance, drought resistance, and hybrid vigour, makes it a valuable asset for South African beef production.
With regard to the development of synthetic breeds, the Brahman is a key ingredient in many of the synthetic breeds found in South Africa, including Simbra (Brahman x Simmental), Braford (Brahman x Hereford), Brangus (Brahman x Angus), Charbray (Brahman x Charolais), and Santa Gertrudis (Brahman x Santa Gertrudis).
Internationally, the following synthetic breeds utilise Brahman genetics: Brahmaine (Brahman x Maine Anjou), Brahmousin (Brahman x Limousin), Droughtmaster (Brahman x Shorthorn), Gelbray (Brahman x Gelbvieh x Red Angus), Greyman (Brahman x Murray Grey), Mandalong (Brahman x Charolais x Chianina x Shorthorn x British White), and Sabre (Brahman x Sussex).
These synthetic breeds combine the desirable traits of different parent breeds, such as heat tolerance and drought resistance from the Brahman, with desirable characteristics from other breeds.
Improvement of existing breeds
Crossbreeding with the Brahman can improve the performance of other breeds, particularly in harsh environments.
In addition, Brahman crosses have shown high hybrid vigour, meaning the offspring often outperform both parent breeds. For example, crossing Brahman with European breeds such as Hereford and Shorthorn can result in cattle with increased heat tolerance and drought resistance while maintaining good growth rates and meat quality.
In a nutshell
The South African beef industry is a significant branch of the agricultural sector, contributing to both economic growth and social wellbeing. As the industry faces various challenges, including drought, flooding, rangeland degradation, disease and feed shortages, these challenges can impact production and herd building efforts.
The Brahman’s ability to thrive in harsh conditions, particularly in hot climates, reduces the costs associated with disease management and feeding, while their strong maternal instincts and calving ease enhance calf survival.
Combining these qualities with the heterosis effect in crossbreeding systems, and it seems almost impossible not to use Brahman genetics.
For more information on the Brahman breed, contact the SA Brahman Society on 051 446 4619/3452 or 051 492 0267/0266, email info@brahman.co.za or visit www.brahman.co.za.
