Tag: Breeding

British and Continental Cattle Breeds
The Farm

British and Continental Cattle Breeds

British and Continental Cattle BreedsThere are many way to categorize cattle breeds—beef and dairy, standard and miniature, commercial and heritage, Bos taurus taurus and Bos taurus indicus. One classification that is frequently used to describe beef breeds is British versus Continental.

The names are rather self-explanatory. British breeds come from the United Kingdom, while Continental breeds come from Continental Europe. But there is more here than meets the eye. British and Continental breeds were developed under vastly different circumstances, giving each type unique characteristics suited to different applications.


British Breeds

America has long had an association with the British Isles, so it was only natural that British cattle breeds predominated on our shores for many years. The foundation of our British cattle population was imported beginning in the late 1700s. These importations continued well into the following century. The vast majority of beef herds in America today are still built on British breeds.

Examples of British breeds include:

While each breed is slightly different, most British breeds share the following characteristics:

  • Small size.
  • Hardiness in cold climates.
  • Early maturity.
  • Fertility.
  • Calving ease.
  • High percentage of waste at slaughter.
  • Marbled beef.
  • Meat tenderness.

British breeds have found niches in both commercial and alternative agriculture due to their adaptability. Although they dominate the industry sale barns, they are also typically the breeds of choice for grassfed beef production. A few of the breeds, such as the Devon, can be used as all-around homestead cattle, providing beef, milk, and draft power for small farms.


British and Continental Cattle BreedsContinental Breeds

Although experiments were made with Continental breeds in the early 1900s, they did not become popular in the United States until the late 1960s and early 1970s, hence their other name—”exotic breeds.” These cattle were costly and difficult to obtain at first, so the process of establishing an American population was expedited by upgrading imports with British cattle already living on our shores. Most Continental breeds were considered purebred after four or five generations of upgrading. They left their mark on the beef industry by promoting the breeding of large-framed cattle, but this trend has abated somewhat in recent years along with the use of Continental genetics.

Examples of Continental breeds include:

Continental breeds vary widely, but they tend to share a few traits:

  • Large size.
  • Late maturity.
  • Rapid weight gain on feed.
  • Large yield of beef.
  • Low percentage of waste at slaughter.
  • Lean beef.

While quite a few of the Continental breeds have potential as dual-purpose beef and dairy animals, they are rarely used in this way in America. One of the most important roles of Continental cattle in the United States is crossbreeding with British breeds to create more desirable beef animals.


British/Continental Crossbred Cattle

The most common goal in crossing British and Continental cattle is to produce beef calves that retain the marbling of the former type, but with the bigger, more muscular package associated with the latter type.

Unfortunately, introducing the positive traits of Continental cattle into a herd can also introduce negative characteristics. In particular, using a Continental bull on a British cow can lead to the conception of a calf far too large for the cow to give birth to unassisted.

These crossbred cattle need plenty of grain to reach their full potential, so they are more commonly found in the feedlot than in a grassfed operation.

An Introduction to Heritage Breeds
The Farm

An Introduction to Heritage Breeds

An Introduction to Heritage BreedsThinking about starting a farm with heritage breeds? If you are new to this topic, you may enjoy An Introduction to Heritage Breeds: Saving and Raising Rare-Breed Livestock and Poultry by The Livestock Conservancy.

This excellent beginner’s resource starts with the basics—defining breeds in general and heritage breeds in particular. It discusses the plight and importance of rare breeds, as well as the necessity to maintain genetic diversity within these breeds despite their falling numbers.

After a look at how different farming systems call for vastly different breeds, An Introduction to Heritage Breeds moves on to considerations of importance to new farmers, helping them honestly assess what species of livestock will best fit their needs and circumstances. Factors to weigh include:

  • Handling ease.
  • Noise and odor level.
  • Shelter and space requirements.
  • Zoning restrictions.
  • Daily food and water requirements.
  • Predator control.
  • Products.
  • Processing and transportation.
  • Potential markets.
  • Breed associations and other resources.

Next comes information on getting started with heritage breeds:

  • Choosing a breed.
  • Providing for the basic needs of your livestock.
  • Setting realistic goals for your project.
  • Setting up a system of animal identification and record-keeping.
  • Planning to market your livestock or livestock products.

Maintaining a heritage breed requires close attention to the principles of genetics and selection, particularly when the breed is teetering on the brink of extinction. An Introduction to Heritage Breeds provides an overview of this process in nontechnical terms. It also demonstrates that rare breeds can be maintained and promoted through breeding projects with very different emphases:

  • Performance and exhibition.
  • Production only.
  • Production and breed conservation combined.
  • Rescue of rare breeds or bloodlines.

The book closes with a look at how breed associations can either help or hurt a rare breed.

While An Introduction to Heritage Breeds is not a comprehensive guide to breeds, it does provide numerous breed snapshots, distilling the most essential facts about the distinctive characteristics of many breeds.

If you are serious about working with heritage breeds, you will quickly outgrow this resource. We recommend supplementing it with resources specific to your chosen species, including a guide to care, a guide to breeding and genetics, and a breed encyclopedia. If you can find any works written entirely about your breed, make it a point to add those to your bookshelf, as well.

An Introduction to Heritage Breeds is exactly what the title suggests—an introduction, concise and clear enough for a reader with no prior experience with animals.


Helpful Resources

Cattle BreedsCattle Breeds
Our own guide to the history, uses, temperament, health, and pros and cons of cattle breeds, including some heritage breeds.

Horse & Donkey BreedsHorse & Donkey Breeds
Our own guide to the history, uses, temperament, health, and pros and cons of horse and donkey breeds, including some heritage breeds.

What is a Landrace Breed?
The Farm

What is a Landrace Breed?

What is a Landrace Breed?

Florida Cracker cattle

A landrace is a group of genetically related animals unique to a given geographical area. Landraces come about over time as animals within the area interbreed for many generations with relatively little outside influence. The fact that all of the animals within the population descend from the same set of ancestors, whether those ancestors came from one source or many, creates a certain level of genetic uniformity. This makes it possible for an observer to distinguish each landrace from other breeds and landraces.

The environment is the major factor that shapes the landrace. If a given animal is not suited to local conditions, it probably will not thrive and produce offspring, eliminating its genes from the population. Instead, other animals that can thrive in those conditions will produce the next generation.

Examples of local conditions that landraces adapt to include:

  • Altitude.
  • Terrain.
  • Temperature.
  • Abundance or scarcity of water.
  • Natural food sources.
  • Parasites.
  • Predators.


The Role of Man in Shaping Landraces

Even though nature has the most say about the gene pool of a landrace population, humans also play a role. Indeed, this element of human intervention is part of what separates a landrace from a feral population.

People shape the genetics of a landrace both passively and actively. Passive selection occurs when humans alter the environment or its natural effect on animals through various management practices. These practices can include:

  • Providing shelter.
  • Providing feed or supplements.
  • Restricting animal movement to specific areas.
  • Doctoring sick animals.
  • Assisting with animal births.

We often consider these practices to be part of good stewardship of our animals, and rightly so. However, the fact remains that most management practices alter the course of nature and enhance the chances of survival and reproduction for animals that otherwise might have left little genetic legacy.

What some animal breeders overlook is that active selection has played a role in shaping many landraces, as well. The history of many landrace breeds show us that humans have specifically chosen certain animals to reproduce due to their desirable traits and have culled others due to their undesirable traits. Sometimes the entire landrace population is shaped in this way, while in other cases one family of breeders has simply established their own bloodline within the broader population.

Humans have actively selected some landraces for:

  • Production.
  • Working ability.
  • Versatility.
  • Specialized purpose.
  • Color.


Landraces Vs. Standardized Breeds

This brings up an important question: If landraces have been actively bred for appearance and production, then is there any difference between a landrace and a standardized breed?

The simple answer is yes.

Note the factors that most landraces have in common:

  • Concentration in a specific geographical area.
  • Limited numbers.
  • Genetic isolation primarily due to geographical isolation.
  • No formal breed association overseeing registry.
  • No written standard.

Compare and contrast this with the characteristics of a standardized breed:

  • Broad geographical distribution.
  • Numbers varying from extremely rare to extremely popular.
  • Genetic isolation primarily due to attention to pure breeding.
  • Registry and promotion by a formal breed association.
  • Written standard of desirable characteristics.

However, now that the Internet has made promoting breeding animals to distant buyers possible, the lines between landrace and standardized breed have become a little more blurred than advocates of either would perhaps prefer.

At present, there is still enough difference between a landrace and a standardized breed to say that the landrace is typically the more genetically diverse of the two. There are exceptions:

  • A landrace breed teetering on the brink of extinction may lose its genetic diversity through population depletion and subsequent inbreeding.
  • A standardized breed may have maintained its original genetic diversity through the preservation of several distinct bloodlines.


Examples of Landraces

Breeds that can still be classified as landraces include:

However, a landrace does not always have to stay a landrace. If a group of breeders decides to pursue more formal breeding methods, the landrace may become the basis of a standardized breed. Examples of landraces that have become standardized include:


Helpful Resource

An Introduction to Heritage BreedsAn Introduction to Heritage Breeds
Excellent book with basic information on landraces and how to preserve their genetics. Read our full review.

Milk Production in Beef Cattle
The Farm

Milk Production in Beef Cattle

Milk Production in Beef CattleIf you have been searching for the right beef cattle breed for your new farm, you undoubtedly have come across plenty of promotional literature published by breed organizations. This material usually includes long lists of the benefits of the breed in question, such as calving ease, rapid weight gain, or meat tenderness.

One characteristic commonly touted is a cow’s milk production. This may give you pause if you are not looking for dual-purpose cattle. After all, what difference does it make if a beef breed is noted for milk production?


Benefits of High Milk Production in Beef Cattle

By producing plenty of milk, a beef cow is producing plenty of food for her calf. The more food the calf has access to at an early age, the heavier the calf will be by weaning time. A study conducted by Oklahoma State shows that the extra milk can translate into as much as 30 extra pounds of calf weaning weight. All other factors being equal, heavier calves tend to bring better prices at sale time.


Drawbacks of High Milk Production in Beef Cattle

All this said, there are reasons why some beef producers still look for more moderate levels of milk production in their cows. When nutrient inputs are limited, cows will channel their energy into three basic directions:

  1. Body maintenance.
  2. Lactation.
  3. Reproduction.

Each of these functions represents a separate “level.” Only if the demands of one “level” are met will surplus energy be channeled into the next level. So lactation will only occur after the body’s basic maintenance needs are met, and the cow will only breed again after she has met her energy requirements for lactation.

Not surprisingly, cows that are heavy milkers need plenty of energy. They require large feed inputs to output all the milk they are capable of producing, and only once their nutrient needs for lactation are met will they be ready to breed again. Heavy-milking cows rarely thrive in a low-input, grass-based system. They tend to form the lowest tier of the herd, the ones that always breed back late. Oklahoma State research shows that heavy-milking cows also tend to have poorer body condition than their lower-milking counterparts.


Choosing the Right Cows For You

As you can see, when considering beef cows based on their milk production, you have to strike a delicate balance. Higher milk production means a heavier, more valuable calf, but it also means a less reliable, more expensive cow.

If you are looking at a grass-based system, you may simply not have the option of using heavy-milking beef cows. If you are planning on providing some supplemental feed, then you will have to count the cost.

Estimates of the dry matter intake of different cows in early lactation are as follows:

  • Cows that produce 10 pounds of milk per day: 26.5 pounds of dry matter per day.
  • Cows that produce 20 pounds of milk per day: 29.0 pounds of dry matter per day.
  • Cows that produce 30 pounds of milk per day: 31.5 pounds of dry matter per day.

Do you have access to an abundant supply of cheap feed? That may decide whether a heavy-milking cow will be an asset or an expense in your system. Keep in mind, however, that you can maintain more low-milk-production cows than heavy-milking cows on the same amount of feed.

Do the math!

What are Scurs
The Farm

What are Scurs?

What are Scurs

Merino sheep clipped to display small scur (dark spot near right ear)

Scurs are horny growths that give some livestock owners concern.  When a scurred animal is young, it may look for all the world like it will grow up to have horns.  Fortunately, this is not the case.

Cattle, sheep, and goats can all develop scurs.  In goats, however, scurs are actually true horns that have been damaged in a bad disbudding job.  In cattle and sheep, scurs are merely inherited growths.  The difference can be felt in mature animals; horns are firmly attached to the skull, while scurs are fairly loose.


Inherited Scurs

Sheep and cattle have a pair of genes that control scurs, represented as Sc for scurs and sc for no scurs.  Scur genes interact with the genes for polling or hornlessness (represented by P for polled and p for horned).  Horned animals with two p genes cannot display scurs, simply because they are horned.  In animals with one P gene and one p gene, males will be scurred if they have at least one Sc gene, while females will only display scurs if they have two Sc genes.  Animals with two P genes will only display scurs if they have two Sc genes.

In addition to the Sc gene, Rambouillet sheep have a similar scurring gene called Sr.  In this breed, both rams and ewes have scurs if they have at least one copy of the Sr gene.

Finally, Suffolk sheep, normally polled, may appear to have scurs.  In this breed, the scurs are actually true horns that have been stunted by interaction with other genes.


Acquired Scurs

There is no definitive evidence that goats inherit scurs.  Instead, scurs on goats appear to be the result of incompletely removing horn buds during disbudding.  If any horn tissue is left alive and in place, it will grow back in the form of a scur.  Bucks, in particular, are prone to scurs due to the influence of hormones.

To avoid this problem, make sure the disbudding iron is thoroughly heated before use.  Disbudding should be done at a young age, while the iron can easily fit around the horn buds.


Removing Scurs

While not all scurs are a problem, some certainly do cause difficulties for both the animal and the owner:

  • In sheep and goats, scurs can curl around and dig their way into the skull if left unchecked.
  • Male animals with scurs tend to break them off while fighting, creating an ugly, bloody mess that is prone to infection.
  • In cattle, scurs reduce the value of an animal, based on the partly erroneous belief that a scurred animal always carries the gene for horned offspring.
  • Scurs may disqualify an animal from the show ring.

Scurs can be banded to cut off the blood supply.  They will eventually fall off, only causing discomfort the last few days.

Small scurs can also be cut off.  This can be painful, however, and care must be taken to seal off the blood vessels with a hot iron.

If you don’t mind routinely trimming scurs, you can also settle for a temporary solution.  Use a wire saw to remove a small part of the scur, making sure that you do not remove enough to cause bleeding.  Goats with small scurs may keep them ground down themselves if provided with a rough, sturdy surface to rub on.  Just bear in mind that the scurs will continue to grow back.

In sheep and cattle, the prevalence of scurs can be reduced in the flock or herd through selective breeding.  This is done by culling all scurred animals.  If the scurred animal is a female, both of her parents can safely be culled, as well, since they both carry the gene.  Note, however, that the culling process will be more complex in Rambouillet sheep, as both the Sc and the Sr genes must be eliminated.  Also, not all Rambouillet sheep that have produced a scurred ewe can be culled, since the ewe might have inherited the Sr gene from only one parent.

Of course, breeders must keep in mind that they may be sacrificing more valuable traits by eliminating scurred livestock.

Get Ready for October 2016
The Lifestyle

Get Ready for October 2016

Get Ready for October 2016October is just around the corner! Are you ready to start a business, explore nature, and live by faith?

  1. Start and run your own small farm business.
  2. Find out how livestock are upgraded.
  3. Explore options for super-small-scale farms.
  4. Identify the wildflowers and grasses of Kansas.
  5. Love God with all your mind.
  6. Save money on seeds.
  7. See the stars.
  8. Understand the importance of the 100th meridian in history.
  9. Ground that wayward chicken.
  10. Discover the key to living by faith.
The Changing Face of American Agriculture: Part 3
The Farm

The Changing Face of American Agriculture: Part 3

The Changing Face of American Agriculture: Part 3High Tech

Many involved in agriculture, commercial or entrepreneurial, feel that technology will shape the future.

The Internet continues to evolve into the driving force in agriculture. Cutting-edge agripreneurs rely on the Internet to market their produce, but even commodity markets are coming to accept this technology as the norm. Buying beef cattle through video auctions streamed online is a common practice nowadays.

Likewise, QR codes for smartphone users will increase in prevalence. Large food manufacturers hope to use these codes to set the minds of consumers at ease about the way their food is grown. Whether or not the QR code will become the primary method of tracking the progress of food from farm to table remains up in the air, however, since the tool has not gained universal acceptance among consumers.

Software will only increase in its capabilities to monitor all aspects of farming. Crop growers may use tracking software to follow the movements of their entire farm fleet. Pork growers suggest that artificial intelligence will be used to forestall production problems of all sorts, including disease outbreaks. Meanwhile, agripreneurs already use logistics software to enhance their competitive edge.

Massive amounts of data are collected in modern agriculture. As researchers and inventors find new ways to quantify conditions in the field, companies will process the data into a variety of charts, graphs, maps, and documents designed to help producers make smart decisions throughout the growing season. Because this work will be so resource-intensive, every farmer’s data will likely end up on the cloud.

Precision planting promises to be a continued focus in commodity farming. Every aspect of the planting process will be computerized to enhance the yield of each individual row in the field. The ability of planters to place seeds at the desired depth and spacing will continue to improve over the next few years. And as the planter moves through the field, it will be collecting a wealth of data that will be processed into decision-making tools to help the farmer push his yields ever higher.

Biotechnology still looks to have a major place in creating the food supply of the future. Pork producers predict that feed crops will be genetically engineered to meet the specific needs of specific animals. Cloning of livestock may become widespread to produce the uniform animals that commodity markets demand. Gene editing may reduce the use of chemical drugs for pest and parasite control. Crops of all types will continue to be engineered for increased yields. However, while biotechnology will continue to bring commodities closer and closer to conventional market specifications, it will increasingly place commercial agriculture at odds with consumers.

Meanwhile, continuing advancements in LED lighting are making growing food indoors possible. LED lights are highly efficient, but they can also be tuned to specific wavelengths to promote better plant growth.


The Changing Face of American AgricultureResearch and Development

Sustainable farming practices are increasingly getting a share of the research money.

Major cities across the country, and even the world, are turning to intensive farming techniques to grow quality foods efficiently. Hydroponics, aeroponics, vertical farming, and indoor gardening are offering ways to grow more in less space. Hoop houses and tunnels are currently hot topics in agricultural research due to their potential to make local food available year-round, even sparking an interest in states that are typically slow to accept alternative farming practices.

Crop scientists will continue to breed new plant varieties. Whereas in the past they have focused on breeding plants for resistance to insects and disease, the future may see them breeding plants that can cope with nonliving threats, such as drought and extreme heat.

Since much of modern conventional agriculture is geared toward growing ethanol, any breakthroughs in biofuel research will be extremely significant. Current research is examining the use of switchgrass as fuel, raising the possibility of converting countless acres of farmland back to grassland. Another energy alternative is that of harvesting crops twice—once for the grain and a second time for stubble to be used as biofuel.

And, one of these days, the man driving the tractor may be a thing of the past, according to grain research experts. He may be replaced with a fleet of fully automated precision farm vehicles. This equipment will be able to navigate using satellites and will even identify and spray weeds with minimal human interference. Currently, the major challenge is designing machinery that can recognize and avoid hitting people, animals, and other objects in the field.


Helpful Resource

How Vermont’s GMO Labeling Law Affects You
Includes information on the pros and cons of various food labeling methods, as well as public sentiment on biotechnology.

Get Ready for September 2016
The Lifestyle

Get Ready for September 2016

Get Ready for September 2016Are you ready for fall?  Spend a little time watching the birds, caring for the animals, and stocking the pantry.

  1. Invest in a dog owner’s home veterinary handbook.
  2. Feed your backyard birds.
  3. Discover why people built round barns.
  4. Stock up for the winter.
  5. Learn about pH.
  6. Weigh the pros and cons of draft animals.
  7. Explore the K-State weather data library.
  8. Open up the breeding toolbox.
  9. Find out how to raise chickens.
  10. Do the Lord’s work in the Lord’s way.
Get Ready for August 2016
The Lifestyle

Get Ready for August 2016

Get Ready for August 2016Even when the afternoons are too hot for outdoor work, you can still make the most of the time with research and planning. Spend some time studying business, marketing, nutrition, animal health, and more.

  1. Consider new ways to direct market your beef.
  2. Find out how reproduction and animal health are related.
  3. Discover 96 horse breeds of North America.
  4. Build a sustainable business.
  5. Learn what kobe beef is.
  6. Ponder the relationship between the railroads and the homesteaders.
  7. Enjoy the wonderful art of drawing horses.
  8. Practice body condition scoring.
  9. Read about the Kansas climate.
  10. Study the roles and natural sources of vitamins.
The Breeding Toolbox: Crossbreeding
The Farm

The Breeding Toolbox: Crossbreeding

The Breeding Toolbox: CrossbreedingCrossbreeding is the final tool in the breeding toolbox. The term crossbreeding in its strictest sense refers to mating two purebred animals of different breeds together. This strict use of the word is typically preferred among pet breeders, but in the livestock realm crossbreeding is sometimes used to cover a wide array of breeding systems involving planned crosses between breeds. This includes breeding rotations involving three or more breeds, as well as the use of composite breeds, which are produced through mixing two or more breeds and then maintaining the resulting offspring as a pure breed. An example of a composite breed would be the “purebred” Braford. (We will use crossbreeding in its broader sense throughout this post.)

Another confusing term related to the practice of crossbreeding is hybrid. Different breeders use this noun very differently. Pearl White Leghorns are sometimes called hybrids even though they are produced by crossing bloodlines of purebred Leghorns—a concept we have already introduced as linecrossing. At the other extreme, in equines a hybrid would be the offspring of a mating between two different species, such as a mule.

Perhaps the best way to explain the term hybrid—at least for the sake of this discussion—would be to define it as any animal that displays hybrid vigor, which would include both the purebred Pearl White Leghorn and the crossbred mule. Thus a hybrid animal could be the product of either linecrossing or crossbreeding.


How It Works

In short, crossbreeding works by pairing unlike genes together to produce the phenomenon of hybrid vigor. Many health, reproductive, and performance traits are inherited in a very complicated manner and appear to be enhanced by hybrid vigor. Some of these traits include:

  • Disease resistance.
  • Longevity.
  • Egg production.
  • Fertility.
  • Milk yield.
  • Rapid growth.
  • Frame size.
  • Weight.

However, hybrid vigor does not guarantee that all crossbred animals will display all of these traits all of the time (more on that below).

The mechanism by which crossbreeding pairs unlike genes together was already discussed in the post on linecrossing. However, because in crossbreeding different breeds instead of different bloodlines of the same breed are involved, the effects are more dramatic. The offspring of a crossbreeding system will end up with more pairs of unlike genes than the offspring of a linecrossing system.

The extent to which variability will be introduced through crossbreeding will depend on how similar the two breeds are to one another and how consistent the genetics are within each breed individually. Hybrid vigor is typically maximized when:

  • Each parent breed is strongly inbred (and therefore very consistent).
  • The two breeds in question are very different from one another in many traits.

These two conditions ensure that the maximum number of unlike genes are paired in the offspring.



Crossbreeding is almost always practiced as a means of capitalizing on hybrid vigor. However, different crossbreeding systems are used to achieve different goals.

In terminal crossing, the crossbred offspring are not expected to reproduce. Two breeds are carefully chosen for their compatibility, each one being expected to bring to the table a specific set of positive traits to offset the negative traits of the other, resulting in offspring that are superior in some way to either parent breed. Those offspring will then be expected to perform in a given manner, such as laying eggs, producing milk, fattening up for slaughter, pulling a plow, or even (in the case of crossbred herding dogs) moving cattle. When the animals have passed their useful life expectancy, they will either be retired or butchered—not bred. This is because hybrid vigor is maximized in the first generation of a cross (more on that below).

Rotational crossbreeding systems involve breeding crossbred offspring back to one of the parent breeds. The offspring of this new mating are then bred to the other parent breed, and so on. Hybrid vigor is significantly reduced but not eliminated after the first generation in this system, since at least a portion of the genes will recombine and form like pairs again, as we will see in a moment. To raise hybrid vigor levels in subsequent generations, some producers introduce new breeds every so often.

In composite breeding, several breeds with desired traits are systematically crossed and recrossed until a stable population achieved. This population is then managed as a pure breed, each animal being mated only to other members of the same composite breed. Obviously, this system is a compromise between consistency and hybrid vigor.

Sometimes crossbreeding is used to improve a pure breed in a practice called upgrading. In this system, the offspring of the initial cross are mated back to animals of the breed being improved. A series of such matings are made until the population reaches a desired percentage of purity. Upgrading is used for three primary purposes:

  • Eliminating inbreeding depression in a rare breed, as was done in Ankole Watusi cattle.
  • Introducing a new trait into an established breed; for example, many beef cattle breeds from Continental Europe were upgraded with Angus cattle to introduce the black coat color.
  • Changing breeds without selling an entire herd or flock and starting over from scratch.



The Breeding Toolbox: Crossbreeding

Red Star hen

Some crossbreeding systems are extremely complicated and require significant capital and a large land base to maintain, since several breeds have to be kept. Simple crossbreeding systems usually take one of two forms:

  • Terminal crossing.
  • Breeding programs that involve a sacrifice of hybrid vigor, such as keeping a composite breed or breeding crossbred animals back to each parent breed in alternation.

The major difficulty with crossbreeding is that hybrid vigor is maximized in the first generation and can only decrease thereafter, since the genes will recombine and often form like pairs again. Take the illustration of the black bull with a genetic formula of BB and the red cow with a formula of bb mentioned in the post on linecrossing. If these two animals are bred to each other, all of their offspring produced over their lifespans will be black, but will have the genetic formula Bb. Note what happens when this new generation is bred:

  • Bb bred to BB produces 50% BB and 50% Bb offspring.
  • Bb bred to bb produces 50% Bb and 50% bb offspring.
  • Bb bred to Bb produces 25% BB, 50% Bb, and 25% bb offspring.

No matter what we breed the hybrid Bb cattle to, we will end up with some like genes paired together once again, and therefore a loss of hybrid vigor.

Furthermore, because there are several ways that each gene pair can combine, mating crossbred animals will inevitably produce inconsistent results. Some of the offspring will be superior animals suitable for carrying on the breeding program, many will be merely average, and some will be very far from achieving the breeder’s goals. If the breeder has ample time and resources, as well as a clear plan, he can gradually shape this population into a stable and useful composite breed. For producers who are looking for the quick fix or the surefire solution, terminal crossing with a proven combination of breeds is probably a better choice.

Another problem is the mysterious aura that surrounds the concept of hybrid vigor. Crossbreeding is not a silver bullet. Crossing animals with poor health and temperaments does not magically produce animals with good health and temperaments, unless the genetic strengths of one parent happen to overlap with the genetic weaknesses of the other parent. In rare cases, the genetic weaknesses of one parent can actually mask the genetic strengths of the other parent. This is why there are proven combinations in animal breeding, crosses that are made over and over again because of their consistent results.

However, compromises must often be made when crossbreeding for hybrid vigor. The boost that hybrid vigor can give to a desired performance trait may come with a price. One of the hybrids preferred for commercial production of brown eggs is a cross between a Plymouth Rock hen and a Rhode Island or New Hampshire rooster. This combination, known by a variety of names including Red Star and Golden Comet, is a spectacular layer thanks to hybrid vigor. It lays tremendous eggs, however, and over time this will affect its health in a number of ways, from depleting its calcium reserves to damaging its internal organs. Likewise, commercial Cornish cross broilers put on the weight fast, growing those big, tender chicken breasts you see at the grocery store. Hybrid vigor causes this incredible growth—at the price of high mortality due to a number of leg and heart problems.

In some cases, a poorly chosen or accidental crossbreeding can result in the phenomenon of outbreeding depression. Outbreeding depression occurs when two populations, each suited for a particular environment or purpose, are crossed, resulting in offspring that are suited for neither environment or purpose. In other words, the crossbred offspring are inferior to both parent breeds, at least for any practical use. An example of outbreeding depression would be a cross between a classic llama and a woolly llama. A classic llama is combed out to collect a tough, durable fiber, although it is more valuable for its working ability. A woolly llama is sheared to obtain a fleece that can be spun like fine sheep’s wool. A crossbred llama has a coat with characteristics of both and the benefits of neither—its fleece contains too much coarse fiber to make a garment that anyone will enjoy wearing, but is too dense and woolly for good temperature regulation when at work. Outbreeding depression is one of the reasons pure breeds arose in the first place and that very specific crosses are favored in situations when a little more hybrid vigor is required.


A Final Thought

As we have seen, all four of the tools in the breeding toolbox have advantages. They all have pitfalls, too. There is no such thing as a silver bullet in any area of life, including animal breeding. Each breeder must decide for himself what his goals are and must make sure that those goals are realistic and useful. Then he must chart his own path, using the tool or ideally a combination of tools that will bring him to those goals step by step.