The benefits of crossbreeding in beef cattle

By Prof. Esté van Marle-Köster (PhD Pr. Anim. Sci)

This week we share another of the excellent topics presented at Zimbabwe Herd Book’s annual Beef School.

Crossbreeding is a smart breeding strategy that has changed beef cattle farming around the world. To understand why farmers choose crossbreeding, we need to look at the basic genetics involved, a powerful benefit called hybrid vigour (or heterosis), and how to choose the right breeds that match your long-term farming goals.

What are your breeding goals?

Every cattle farmer has similar goals: keeping fertility high, raising cows that are good mothers with enough milk, getting more kilograms of beef to sell, and having healthier animals that need less veterinary care. When you're thinking about crossbreeding, these goals need to fit with your bigger picture plans.

Back in 1991, researcher Gosey pointed out something that still holds true today: your breeding plans must work with your farm's reality. This means considering what size of cows you can maintain, what feed you have available, how the seasons change, what the climate is like, and where you can sell your cattle. These are basic reminders that matter for planning ahead.

How does crossbreeding work?

Crossbreeding means mating animals from two different breeds that aren't related to each other. The more different the two parent breeds are genetically, the larger the hybrid vigour effect you'll get. This is different from outcrossing, which means breeding unrelated animals within the same breed to avoid inbreeding problems. Crossbreeding creates much bigger genetic differences than outcrossing does.

What happens genetically is that you're mixing different genes from both breeds, creating offspring that have a diverse genetic makeup. Compare this to pure breeding, where animals are more genetically similar. The biggest benefits from crossbreeding show up in traits that are harder to improve through normal selection.

What is hybrid vigour (heterosis)?

Hybrid vigour happens when crossbred calves perform better than the average of both parent breeds for a particular trait. Here's how you work it out: take the crossbred average, subtract the purebred average, divide by the purebred average, and multiply by 100 to get a percentage.

Let's use a real example with weaning weight. Say breed A calves average 180 kg, breed B calves average 205 kg, and when you cross them the calves average between 200 and 205 kg. The crossbred average would be 202.5 kg and the purebred average would be 192.5 kg. That's a 10 kg advantage, which works out to about 5% hybrid vigour.

Why should you crossbreed?

There are two main reasons to crossbreed. First, you get hybrid vigour, which gives you better-performing animals. Second, you can benefit from complementarity by combining the best qualities of two different breeds. This strategy lets you maximise the strengths of each breed whilst minimising their weaknesses.

Which traits benefit most?

Research shows clear patterns in which traits improve most with crossbreeding. Traits that are hardest to improve through normal selection (low heritability) get the biggest boost from hybrid vigour, with improvements of 10 to 30%. These include cow longevity (how many years she stays productive), health, mothering ability, and fertility. These traits are harder to measure, affected more by environment and management, but they have huge economic value.

Traits like early growth, growth rate, and milk production get moderate benefits of 5 to 10%. Traits that are easiest to improve through selection (high heritability), like carcass measurements and mature size, only get small benefits of 0 to 5% from crossbreeding.

This makes sense: crossbreeding works best for fertility, mothering ability, and disease resistance - exactly the traits that are most valuable but hardest to improve through normal selection.

How hybrid vigour works in individuals and mothers

Hybrid vigour shows up in two ways: in the crossbred animal itself and through the crossbred mother's effects on her calves. Research from 1988 measured these effects across different traits.

For calving rate (how many cows actually calve), the benefit from having a crossbred mother adds 6%, whilst there's no extra benefit from the calf being crossbred. Birth weight gets 4% from the calf being crossbred and 2% from the mother, totalling 6%. Weaning weight gets 5% from the calf and 6% from the mother, totalling an impressive 11%. Most remarkably, cow longevity improves by 38% overall.

Age at first calving improves (negative 3%), and temperament can worsen depending on which breeds you combine. Cow efficiency improves by about 2%.

Choosing the right breed combinations

The key to successful crossbreeding is exploiting hybrid vigour for mothering traits and matching breeds that complement each other. One important thing to understand: hybrid vigour itself doesn't pass to the next generation - you need to keep crossbreeding to maintain it.

In practical terms, success means matching breeds based on which traits you want to improve in your production system, selecting your foundation breeds and bull breeds based on available performance records, and choosing breeds whose strengths complement each other.

What large research projects have found

The US Meat Animal Research Centre tested 30 different sire breeds by mating them with Angus and Hereford cows. This massive research project has produced valuable information comparing different crosses and continues today, examining how different breeds perform in various environments.

The data shows important patterns. When you cross two Bos taurus (European) breeds, calving rate improves by about 3-4%. Birth weight increases slightly, and weaning weight goes up by 7-8 kg. The real magic happens when you cross Bos taurus with Bos indicus (Zebu-type) breeds - weaning weight jumps by over 35 kg!

Choosing Breeds in Your Region

In the United States, about 60 different breeds exist, but 10 breeds produce most of the beef. South Africa has around 30 breeds, with several contributing significantly to beef production. Most beef comes from crossbred weaners sent to feedlots, which tells you crossbreeding works in commercial production.

South African breed options options

South Africa's stud industry, serviced by the South African Stud Book and the Livestock Registering Federation (LRF), tracks all registered breeds. Bonsmara is the largest participant with 271 herds and over 111,000 animals. Brangus breeders numbering 184 have 59,500 while Brahman breeders numbering 357 have 56,700 animals. Beefmaster operations include 113 herds with almost 56,000 animals. There are 146 Simbra breeders with 36,000 animals and 188 Simmentaler breeders with 29,800 animals. Angus farmers run 106 herds with nearly 17,000 animals. Boran, Braford, Drakensberger, Limousin, Nguni, and Tuli also participate with smaller but significant numbers.

Different breed types show different characteristics. Sanga types average 31 kg at birth, 189 kg at weaning, and heifers first calve at 33 months. European (Bos taurus) types are bigger: 37 kg at birth, 220 kg at weaning, also first calving at 33 months. Zebu (Bos indicus) types are smaller: 29 kg at birth, 181 kg at weaning, first calving at 34 months. Composite breeds (purpose-bred crosses) average 35 kg at birth, 221 kg at weaning, and 31 months to first calving.

In South African breeding programmes, composite breeds make up 59% whilst pure breeds account for 41%. The breed makeup varies between stud farms, feedlots, and emerging farmers, with different proportions of Sanga, British, Zebu, and Continental genetics.

Mother cows versus terminal sires

Successful crossbreeding programmes typically use mother cow lines that are well-adapted to your specific environment, especially if conditions are challenging. These cows are usually small to medium-framed, which means they don't cost much to maintain, they live for many years, and they resist diseases well. Bull breeds (sires) are chosen mainly for growth and feed efficiency.

Research looking at mature cow weight and body condition found that hybrid vigour adds about 22 kg to mature weight and improves body condition score. This confirms that breed differences and hybrid vigour are important when comparing different crosses.

** See below for more on mother cow lines and terminal sires

Comparing different crosses

Different breed combinations produce different levels of hybrid vigour. When you cross two British breeds together, or British with Continental European breeds, or two Continental breeds, you get similar results: small improvements in birth weight, around 10 kg advantage at weaning, and about 4 kg extra post-weaning gain.

When you cross British or Continental breeds with Zebu breeds, the benefits jump dramatically: birth weight advantages triple, weaning weight advantage more than doubles to nearly 22 kg, and post-weaning gain increases to nearly 13 kg. This shows why Zebu genetics are so valuable in crossbreeding programmes.

How much Brahman is best?

Research in subtropical and tropical areas often uses adapted mother cow lines, with Zebu breeds like Brahman being very popular. A 2024 study tested different amounts of Brahman genetics in cows (crossed with Angus bulls) and found some surprising results.

Calves with 21% to 78% Brahman genetics performed better than calves with either very little Brahman (0-19%) or mostly Brahman (81-100%). The standard Brangus breed (38% Brahman) worked well, but so did a wider range. Birth weights were best with 21-34% Brahman. Weaning weights peaked when cows had 41-59% Brahman genetics, with calves averaging 253 kg compared to only 221 kg for those from mostly Brahman cows. The research recommends keeping Brahman genetics between 21% and 78% in your crossbred cows.

Using Sanga breeds

Sanga breeds like Mashona, Nkone, Nguni and Tuli make excellent mother cow lines, especially when you consider your production system and target markets. These indigenous African breeds are well-adapted whilst contributing to hybrid vigour when crossed with complementary bull breeds.

Final thoughts

Crossbreeding offers real benefits for beef production by taking advantage of hybrid vigour, particularly for traits like fertility and mothering ability that are hard to improve through selection. It plays an important role in commercial cow-calf operations, but you need to plan carefully.

Your reasons for crossbreeding must match your long-term goals, your farm's environment and resources, and what your markets want. When you get these factors balanced properly, crossbreeding becomes a powerful tool for improving how much you produce, how profitable your operation is, and how sustainable your beef business will be over time.

Remember: crossbreeding isn't a quick fix, but a long-term strategy. Choose your breeds carefully, keep good records, and stick to your plan. The benefits of hybrid vigour, especially in fertility, cow longevity, and calf survival, can make a real difference to your bottom line.

** Understanding mother cow lines and terminal sires

Mother Cow Lines (maternal breeds)

A mother cow line refers to the breeds you keep as your permanent breeding cows, the foundation of your herd. These are the cows that will stay on your farm year after year, producing calves. When choosing mother cow lines, you're looking for breeds with specific qualities:

• Adaptability: They must thrive in your local environment, whether that's hot, cold, dry, or humid conditions
• Fertility: They need to calve regularly and easily, ideally every year
• Longevity: Good mother cows stay productive for 10-12 years or more, which spreads out the cost of raising them
• Mothering ability: They need strong maternal instincts, produce enough milk, and protect their calves
• Low maintenance: Smaller to medium-framed cows that don't need expensive feed to maintain condition
• Hardiness: Resistance to local diseases and parasites, able to handle tough conditions

In southern Africa, good examples of mother cow line breeds include Sanga, Boran, and Brahman crosses. These breeds have adapted to local conditions over many years and are efficient at raising calves in challenging environments.

Terminal sires (bull breeds)

A terminal sire is a bull breed used specifically to produce calves for slaughter (market), not for breeding replacements. The word "terminal" means the end of the line - these calves go to market, they don't stay in the breeding herd. Terminal sires are chosen for completely different reasons than mother cow breeds:

• Growth rate: Fast-growing calves reach market weight sooner
• Feed efficiency: They convert feed to meat efficiently, reducing production costs
• Muscling: Heavy muscling and good carcass quality bring better prices
• Frame size: Usually larger-framed breeds that produce bigger calves

These bulls are mated to your crossbred mother cows to produce calves that combine the mother's hardiness and fertility with the father's growth and meat quality.

How they work together

The beauty of this system is that you get the best of both worlds. Your mother cows benefit from hybrid vigour for fertility and survival (the traits that matter most in breeding cows), whilst the calves benefit from their sire's growth genetics. For example, you might keep Nguni x Brahman crossbred cows (adapted, fertile, long-lived) and breed them to a Simmental bull (growth, muscling) to produce calves that grow fast for the feedlot or market.

This two-breed or three-breed system is how most commercial beef in South Africa is produced. The mother cows stay productive in tough conditions, whilst the market calves have the size and quality that buyers want.