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The worth of heterosis, crossbreeding in the beef value chain

Bob Weaber Published on 24 December 2012
Cows

Recently, there have been dramatic increases in input costs for feed, fertilizer and fuel which have again narrowed profit margins of many cow-calf producers and others in the beef value chain.

These challenges to profitability have motivated many producers to analyze their production systems and consider management strategies that improve operational efficiency.

Profitability may be enhanced by increasing the volume of production (i.e. the pounds of calves you market) and/or the value of products you sell (improving quality).

The reduction of production costs, and thus breakeven prices, can also improve profitability.

For commercial beef producers, the implementation of technologies and breeding systems that increase the quality and volume of production and reduce input costs is essential to maintain or improve the competitive position of the operation.

More and more producers are finding that a structured crossbreeding system helps them achieve the goals of increasing productivity and reducing production costs.

Why crossbreed?

The use of crossbreeding offers two distinct and important advantages over the use of a single breed. First, crossbred animals have heterosis or hybrid vigor.

Second, crossbred animals combine the strengths of the parent breeds. The term “breed complementarity” is often used to describe breed combinations that produce highly desirable progeny for a broad range of traits.

What is heterosis?

“Heterosis is defined as the average advantage of a crossbred individual over the average of its purebred parental breeds,” explains Dr. Larry Kuehn.

Kuehn is a research geneticist at the USDA’s Meat Animal Research Center, Clay Center, Nebraska.

He continues that, “While it is possible for one of the parental breeds to be more advantageous for a specific trait, it is unlikely that any one breed can be superior to a crossbred animal for all overall production efficiency.

The crossbred advantage is particularly pronounced in the performance of crossbred dams.”

Heterosis results from the increase in the heterozygosity of a crossbred animal’s genetic makeup. Heterozygosity refers to a state where an animal has two different forms of a gene.

It is believed that heterosis is the result of gene dominance and the recovery from accumulated inbreeding depression of pure breeds. Heterosis is, therefore, dependent on an animal having two different copies of a gene, each originating from a different breed.

The level of heterozygosity an animal has depends on the random inheritance of copies of genes from its parents.

In general, animals which are crosses of unrelated breeds, such as Angus and Brahman, exhibit higher levels of heterosis, due to more heterozygosity, than do crosses of more genetically similar breeds such as a cross of Angus and Hereford.

Heterosis generates the largest improvement in lowly heritable traits. Moderate improvements due to heterosis are seen in moderately heritable traits. Little or no heterosis is observed in highly heritable traits.

Heritability is the proportion of the observable variation in a trait between animals that is due to the genetics passed between generations and the variation observed in the animal’s phenotypes, which are the result of genetic and environmental effects.

Dr. Larry Cundiff, retired research geneticist at the USDA Meat Animal Research Center, reinforces the point by adding, “Purebred superiority is more likely when traits are moderately heritable (e.g, milk production in dairy cattle, carcass merit), partially due to the effectiveness of past selection.

On the other hand, traits with lower heritability, such as calf survival, longevity, and fertility, benefit significantly from heterosis.” Improvement in these traits via selection has been difficult.

Crossbreeding has been shown to be an efficient method to improve reproductive efficiency and productivity in beef cattle.

Improvements in cow-calf production due to heterosis are attributable to having both a crossbred cow and a crossbred calf.

Table 1: Effects of cindividual heterosis on performance of crossbred calves

Table 1 and 2 detail the individual (crossbred calf) and maternal (crossbred cow) heterosis observed for various important production traits.

Dr. Cundiff says “Research has demonstrated that heterosis favorably influences the output per cow in a herd by approximately 25 percent.

Table 2: Maternal heterosis effects on calf traits tied to environment, productivity, longevity

Over half of this increase is from the use of a crossbred cow.

Economic analyses have shown that this increase in output equates to a reduction of 8-10 percent in cost of production.

Herdlife of crossbred cows is almost 1.5 years longer on average relative to purebred cows under normal commercial production.”

The heterosis generated in calves that are the progeny of straight-bred parents of different breeds or crossbred parents is called individual heterosis.

While this type of heterosis has important effects on economically important traits, it only accounts for approximately one-third of the total economic benefits of having crossbred cows and calves.

Individual heterosis improves performance in a number of traits measured on calves including survival and growth (Table 1.).

For example, individual heterosis can improve weaning weights by nearly 4 percent, which on a 500-pound weaned calf is 20 pounds.

Why is it so important to have crossbred cows?

The production of crossbred calves yields advantages in both heterosis and the blending of desirable traits from two or more breeds.

However, the largest economic benefit of crossbreeding to commercial producers comes from having crossbred cows. Maternal heterosis improves both the environment a cow provides for her calf as well as improves the longevity and durability of the cow.

The improvement of the maternal environment a cow provides for her calf is manifested in the improvements in calf survivability to weaning and increased weaning weight.

Crossbred cows exhibit improvements in calving rate of nearly 4 percent and an increase in longevity of more than one year due to heterotic effects (Table 2).

Heterosis results in increases in lifetime productivity of approximately one calf and 600 pounds of calf weaning weight over the lifetime of the cow (Table 2).

Crossbreeding can have positive effects on a ranch’s bottom line by not only increasing the quality and gross pay weight of calves produced but also by increasing the durability and productivity of the cow factory. Crossbred cows may be the only free lunch in the world.

The effects of maternal heterosis on the economic measures of cow-calf production have been shown to be very positive.

The added value of maternal heterosis ranges from approximately $50 per cow per year to nearly $100 per cow per year depending on the amount of maternal heterosis retained in the cow herd. Maternal heterosis accounted for an increase in net profit per cow of nearly $75 per cow per year.

How can I harness the power of breed complementarity?

Breed complementarity is the effect of combining breeds that have different strengths. When considering crossbreeding from the standpoint of producing replacement females, one could select breeds that have complementary maternal traits such that females are most ideally matched to their production environment.

Matings to produce calves for market should focus on complementing the traits of the cows and fine-tuning calf performance (growth and carcass traits) to the market place.

There is an abundance of research that describes the core competencies (biological type) of many of today’s commonly used beef breeds. Traits are typically combined into groupings such as maternal/reproduction, growth and carcass.

When selecting animals for a crossbreeding system, their breed should be your first consideration.

What breeds you select for inclusion in your mating program will be dependent on a number of factors including the current breed composition of your cow herd, your forage and production environment, your replacement female development system, and your calf marketing endpoint.

All of these factors help determine the relative importance of traits for each production phase.

What are the keys to successful crossbreeding programs?

“As a final note, commercial producers have often enjoyed the benefits of crossbreeding in an initial cross, only to see those benefits erode due to mating back to the same breed of bull in the next generation; the progeny become graded-up purebreds, thereby losing the benefits of heterosis.

This erosion of heterosis can be effectively managed through the use of crossbreeding systems (terminal cross, composites, rotational breeding, etc.),” concludes Dr. Cundiff.

Many of the challenges associated with crossbreeding systems in the past are the result of undisciplined implementation of the system.

With that in mind, one should be cautious to select a mating system that matches the amount of labor and expertise available to appropriately implement the system.

Crossbreeding systems range in complexity from very simple programs such as the use of hybrid genetics, which are as easy to use as straight breeding, to elaborate rotational crossbreeding systems with four or more breed inputs.

The biggest keys to success are the thoughtful construction of a plan and the sticking to it! Be sure to set attainable goals. Discipline is essential.  end mark

Bob Weaber is an assistant professor and cow-calf extension specialist at Kansas State University.

This originally appeared in a publication for the North American Limousin Foundation.

PHOTO

Animals that are crosses of unrelated breeds, such as Angus and Brahman, exhibit higher levels of heterosis, due to more heterozygosity crosses of similar breeds. Photo courtesy of Progressive Cattleman staff.

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