Photo by Sam Wirzba
Whether you’re talking cattle, corn or hogs, heterosis (hybrid vigor) has proven its value. There are three kinds of heterosis in cattle – individual (the calf), maternal and paternal. Of the trio, paternal heterosis has received the least attention.
Research trials report up to a 25% increase in pounds of calf weaned per cow exposed to a bull when crossbred cows produce crossbred calves. Crossbred calves demonstrate increased weaning weights and yearling weights when compared with the average of parent breeds.
Maternal heterosis in a cow increases her performance and that of her calves. She reaches puberty earlier, rebreeds more quickly, her calves have greater survivability, she stays in the herd longer, and she produces more pounds of calf during her lifetime. Now some producers are looking at possible advantages of utilizing paternal heterosis, and improving reproductive characteristics of the bull.
Wade Shafer, American Simmental Association (ASA) director of performance programs, has worked with ASA’s multi-breed genetic evaluation, comparing seedstock of all breeds and breed combinations.
“Crossbred sires simplify crossbreeding. After you’ve settled on an optimal proportion for your herd, you can keep it that way by using crossbred bulls,” Shafer says.
“If you want a half-Simmental, half-Angus cowherd, and start with Angus cows, you can use a Simmental bull and produce heifers of the desired mix. The next step is to use a SimAngus bull on those heifers to maintain the desired proportion of each breed. This results in higher uniformity than if you rotate back and forth between purebred sires,” he explains.
Shafer says the beef industry has long encouraged use of purebred sires in rotational crossbreeding systems. Academics point out that rotational systems using purebred bulls produce slightly more heterosis. For example, a two-breed rotation using purebred sires will settle at 68% of maximum heterosis. Meanwhile, two-breed, half-blood sires on a herd with the same breed composition will result in 50% of maximum heterosis.
“But it’s very cumbersome to maintain a rotational crossbreeding system, as it requires sorting bulls and females into multiple breeding pastures. With crossbred seedstock, you can maintain nearly as much heterosis and it’s as simple as a straightbred system – you just turn out the bulls,” Shafer says.
Jack Whittier, Colorado State University Extension beef specialist, says one of the driving factors behind increased use of hybrid bulls is the fact that many cowherds have become less crossbred. “Using a crossbred or composite bull can restore heterosis – in a much more simple way than using elaborate rotational crossbreeding systems,” he says.
Scott Greiner, Virginia Tech Extension beef cattle specialist, says hybrid bulls allow for practical crossbreeding, especially in small herds. “The traditional rotational or terminal sire systems are not applicable,” he says. The producer may have only one breeding pasture and one bull.
“By using a hybrid bull, heterosis can be introduced. By keeping the heifers, maternal heterosis can be added, in a simple and practical fashion, without having wide fluctuations in breed composition from one generation to the next,” he says.
Mark Thallman, a research geneticist at the U.S. Meat Animal Research Center (MARC) in Clay Center, NE, says more heterosis is possible with an F1 bull than with a composite bull.
“However, if you want to maximize heterosis throughout the herd or system, you’re better off with a four-breed composite, or to use more than two breeds in a crossbreeding program. With a four-breed composite, you get a little less heterosis from the bull himself, but more heterosis across the whole system,” he explains.
Another option is to use a crossbred bull that incorporates two breeds not found in the crossbred cows – creating a calf with genetics of four breeds, for maximum heterosis.
“One caution about composites or hybrids is that you have to be just as careful about inbreeding with them as you do with straightbreds,” Whittier says. “As inbreeding increases, heterosis decreases. If you’re using hybrid bulls to get heterosis back into your cows, be careful to not keep using the same lines, or you’ll lose that advantage.”
“Another important benefit, independent of heterosis, is the complementarity that hybrids bring. You don’t have to deal with the big swings in cow size or biological type that occur when using purebred bulls of one breed and then another,” Whittier says.
“There are many different breeds being used in creating composites, but the ones most discussed include SimAngus (Simmental-Angus), Balancer (Gelbvieh-Angus) and LimFlex (Limousin-Angus). Any of those three continental breeds appear to be fairly complementary with Angus, which explains their acceptance,” Whittier says.
This is a very powerful tool. “Using crossbred seedstock allows commercial producers to fully utilize complementarity while maintaining consistency,” Shafer says. Staying within one breed severely limits selection of sires to complement your herd.
“Complementarity is most thoroughly exploited by crossing diverse biological types, but using purebred bulls in a rotational crossbreeding system creates large variations in breed proportion within the herd – and lack of uniformity. To counteract this, a producer may select breeds of similar biological type. This approach delivers consistency, but does not leverage the power of complementarity. With use of crossbred sires, you can maintain a constant breed proportion, and uniformity will be maintained in spite of utilizing diverse breeds,” Shafer explains.
Hybrid bulls have higher-than-average fertility and longevity. “Those traits appear to be a natural result of heterosis,” Whittier says. He’s referring to a summary of research on crossbred sires that appeared in the Journal of Animal Science in 1987.
“Kentucky researchers reviewed nine published reports that dealt with productivity of crossbred bulls, focusing primarily on reproductive traits of yearling crossbred and straightbred bulls. The researchers looked at semen traits and fertility, and found increased survivability of sperm in crossbred bulls, which might have an influence on overall pregnancy rate,” he says.
Crossbred bulls compared to parent breeds showed advantages in semen quality, age at puberty, scrotal circumference and pregnancy rates, he says. Hybrid bulls also reached puberty at an earlier age, had improvements in scrotal circumference, improved sperm concentration, and increased pregnancy and weaning rates in the cows they bred.
Another interesting fact is that average date of calves born when sired by crossbred bulls was 8-10 days earlier than calves sired by purebred bulls, indicating earlier conception. The payoff is that calves born earlier have more time to grow before weaning, and cows that calve earlier have more chance to rebreed on schedule earlier in the season.
Improved sperm traits are also an advantage of hybrid bulls. “Greater concentration of sperm cells and improved initial motility should enhance collection, extension and freezing from hybrid sires for artificial insemination. These traits would also improve the ability of young hybrid bulls to successfully pass a breeding soundness exam prior to being offered as yearling sires,” Whittier says. He adds that these results are now being seen, as more hybrid and composite bulls are used for artificial insemination.
Producers who have used hybrid bulls feel one advantage over purebreds is that the hybrid bull has a tendency to stay structurally and reproductively sound longer, with fewer breakdowns. This depends partly on the individual bull, of course. “There hasn’t been much research on this, but we know crossbred cows stay in the herd longer, and we feel the crossbred bulls would, too,” says Matt Spangler, a University of Nebraska assistant professor in beef cattle quantitative genetics.
Today, a growing number of seedstock producers supply a variety of hybrids – giving commercial cattlemen many options in breed choices.
“When selecting any bull, producers need to concentrate on things that have always been important – soundness, disposition, as much performance information as possible, and use of multi-breed EPD computations. The knowledge of a bull’s genetic potential is more easily obtained today,” Spangler says. Some of the same tools are available today in composite bull selection as in purebred selection, including EPDs, accuracies and index values, he adds.
“Buyers need to realize that just because bulls are hybrids doesn’t necessarily make them superstars. All the things that go into bull selection still need to be strongly considered. This includes reputation of the breeder, performance of the individual and any records the bull might have,” Whittier says.
“People need to also realize that composite bulls aren’t immune to the genetic defects that have plagued purebred cattle recently,” Spangler adds. It all depends on the genetics of the cattle used in creating the composite.
Seedstock producers must be careful in their selections of parent stock. “They know the pedigrees, which animals are at risk, and hopefully DNA-test the appropriate ones, to avoid passing on any undesirable defects. This is something bull buyers need to be aware of,” Spangler stresses. Remember, the composite isn’t a new breed; it’s a mix of the old ones.
“Today, there’s renewed interest in hybrid vigor and crossbreeding,” Greiner says. “The last several years have also seen an evolution in the tools and science to do accurate genetic selection with hybrid bulls. We’ve put purebreds and hybrids on the same playing field.”
This has generated more interest in hybrid bulls. They’re now considered seedstock, a term that no longer refers only to purebreds. “Many breeders have two breeds in their operation and are mating some to produce hybrids. Breeders see this as a way to provide a full-service opportunity for customers, giving them more options,” Whittier says.
“The quality and genetic merit of the average hybrid bull today is a lot better than it was a few years ago,” Greiner says. Early on, a crossbred bull was not necessarily from a planned mating. In some programs, it might have been the late-calving cows or those that didn’t produce the best calves that were mated to another breed.
“But this isn’t true anymore. Breeders today are flushing their best cows to make hybrids, and bull buyers have faith in the quality of the bulls. The use of hybrids has grown astronomically,” Greiner says. Commercial cattlemen are looking at what hybrids can offer their breeding programs – with various percentages of continental and British breeding.
“When academics first started talking about composite bulls, it was nice in theory, but there were not very many places you could get a hybrid bull,” Spangler says. “This has changed. Now many seedstock producers offer F1 bulls and a growing number produce any desired mix – such as 3/8 Continental breeding and 5/8 British, or the reverse. Availability is not an issue anymore.”
“The beef industry uses the terms composite and hybrid interchangeably, and sometimes not totally accurately. Either way, they are animals with more than one breed in their pedigree,” says Jack Whittier, Colorado State University Extension beef specialist.
A hybrid can be any crossbred, whereas a true composite is created using a large population of cattle, with planning – and several generations of selective breeding – to create animals that have the same percentage of a certain mix. It might be ¾ British breeds and ¼ continental. Another composite might be roughly equal percentages of three different breeds. Whatever the mix, the animals are uniform and all contain that specific blend.
The term composite refers to a group of cattle made up of more than two breeds, created in a systematic manner using at least 25 sires from each parent breed, and then making sure inbreeding doesn’t occur.
Thus, a true composite needs a large population of animals for the initial foundation.
Accepting hybrids as seedstock
Eventually we’ll get past the notion that only purebreds are seedstock. “The swine and poultry industry have already moved that direction. Even the dairy industry is starting to do more crossbreeding; in New Zealand, the most popular dairy cow is a Jersey-Holstein they call Kiwicross. They’ve blended the good traits from both breeds and are also getting heterosis. These cattle work very well in forage-based dairies,” says Jack Whittier, Colorado State University Extension beef specialist.
You can more readily create animals that excel in a particular environment or management system when you cross certain breeds to get the traits you want. Innovative cattlemen have been doing this for a long time.
“Historically, we’ve known for decades that crossbreeding can improve profitability, yet crossbreeding has not dominated our industry like it has in other food production industries,” says Wade Shafer, American Simmental Association (ASA) director of performance programs. “One reason is that breed associations have spent a lot of money and effort promoting the concept that seedstock have to be purebred. This idea is deeply entrenched,” he says.
“The chicken and swine industry figured out a long time ago that composites work very effectively as seedstock. Some beef breeders also figured this out, but they were ostracized by breed associations,” Shafer says.
Some of the early composites in this country – Brangus, Santa Gertrudis, Beefmaster, Braford, etc. – gained acceptability because they were promoted as breeds. “Today we also have Simbrah. That’s clearly a composite just like Brangus and Santa Gertrudis, but those were called breeds to give them legitimacy. Now that veil has lifted, and today it’s ok to have composite seedstock. Yet there are still people within the breed associations and commercial industry who feel composites are inferior,” he says.
“There was a time when a breeder was blackballed for doing something like this,” Whittier says. “The recognition of research data and realities of heterosis have allowed the industry to adapt and accept this better, today.”
Matt Spangler, University of Nebraska assistant professor in beef cattle quantitative genetics, says the important thing is breeding superior animals, and these often come from crossbred lines. “If the animals can consistently pass on superior genetics, that’s what we want – and this is what makes them seedstock, whether they are purebred or a blend of breeds.”
What about uniformity?
“Research done a couple decades ago by the U.S. Meat Animal Research Center (MARC) on composites clarified that they do have a role in the beef industry, and that they breed true. Phenotypic variation within composite populations was no different than phenotypic variation in the parent breeds. Three or four decades ago, there was a stigma among cattle producers that composites would have greater variation (less uniformity), but the MARC research did not bear this out,” says Jack Whittier, Colorado State University Extension beef specialist.
“People were concerned about using composite bulls because they wanted all their calves black-hided,” says Matt Spangler, University of Nebraska assistant professor in beef cattle quantitative genetics. “But we can get homozygous black, homozygous polled composite bulls, and things like color and horns are no longer a concern.”
Heather Smith Thomas is a rancher and freelance writer based in Salmon, ID.