*Written for an English class many years ago. I've since gone through and edited some things, and some still needs to be edited further, but the basics are there!
“If rabbits bred like rabbits, I’d be a billionaire.” Another breeder of Holland Lop rabbits, shared this wisdom with me when I visited her barn to select a new doe. The rabbit I ultimately choose cost me $300. That may seem expensive, but, in truth, I wasn't buying a rabbit. I was buying nearly seventy years of carefully selected genetic codes that were passed on from one generation to the next as breeders strived to create the perfect Holland Lop rabbit. Methods of breeding such as crossbreeding, out-crossing, and line-breeding have been used to create the ideal Holland Lop. The fundamental difference between these methods lies in the relationship between the rabbits that are being bred. Because every breeder and every rabbit is different, there is much disagreement on what is the ‘correct’ way to use these methods.
Crossbreeding refers to mating rabbits of different breeds to create offspring that are drastically different from their parents. This method was used to create the Holland Lop when in 1951 Adrian de Cock crossed a Netherland Dwarf buck (male rabbit) with a French Lop doe (female rabbit). This essentially created a rabbit with the small size of the Netherland Dwarf and the floppy ears of the French Lop. This result could not have been achieved without crossbreeding. Crossbreeding can also help establish a new color gene into a breed. For example, Holland Lops were originally only solid-patterned, with no broken-patterned (solid color with white patches) rabbits available. Some Holland Lop breeders wished to create the Broken variety in the Holland Lop breed, and had to resort to crossbreeding because the gene for broken pattern simply did not exist in the Holland Lop breed. Holland Lops were crossbred with English Spots, and successfully created the Broken Pattern. However, the resultant Holland Lops did not have the rollback fur (fur that rolls back slowly when stroked the wrong way) that is called for in the ARBA breed standard. This resulted in a second crossbreeding between Broken Holland Lops and a breed known as the French Angora in order to regain the rollback coat. Breeders were able to recreate the rollback coat, but unfortunately the French Angora, being a wool breed, passed the recessive wool gene to their Holland Lop offspring. This meant that when two wool carrier Holland Lops were bred, approximately 25% of the resultant offspring had wool coats. These wooly Holland Lops were later developed into a new breed – the American Fuzzy Lop.
A key disadvantage of crossbreeding is that the rabbits are no longer ‘purebred.’ Unless the crossbreeding was farther back than the rabbit’s great-grandparents, the rabbit is considered a mixed breed. However, the animal may still be shown and even win, provided it visually looks like its breed. Another disadvantage is that because the progeny are mixed breed, they might be less desirable for other breeders to buy as show or brood animals. Crossbreeding without a clear and specific goal could risk a breeder's reputation, and it may introduce undesirable characteristics into the gene pool along with any desired benefits. While it is certainly possible to have success crossbreeding rabbits with clear and specific goals in mind, in most cases, there isn't much of a benefit, especially in popular breeds with quality animals and a large, healthy gene pool.
A safer method of breeding is outcrossing. Outcrossing is the breeding of two rabbits that are of the same breed but are from unrelated lines. This usually means they share none of the same rabbits in their pedigree. On the positive side, a good outcross can greatly strengthen weak areas in your herd. For example, I recently purchased a new Holland Lop buck. He is unrelated to my current rabbits, so would be considered an outcross. My current rabbits have excellent hindquarters but lack a wide ear base. In contrast, my new buck has less optimal hindquarters, but a very good ear base. When I outcross him to my rabbits, I can expect that a portion of his descendants could have great hindquarters and great bone density. Being able to produce those more superior rabbits is the true value of an outcross. Therefore, by some degree of random genetic chance, I can get some excellent offspring that have the advantages of both the outcross and my pre-existing stock. However, I could also produce rabbits with the disadvantages of both their parents, or even new, unexpected disadvantages. There are no guarantees, and outcrossing successfully may take several generations to successfully integrate a new line into your program. A breeder must keep these benefits and risks in mind when making the decision to outcross.
Outcrossing can also improve a herd’s vigor, or, its overall thriftiness and health. If a line of rabbits is bred only to other related rabbits for a long period of time, they lose some heterozygosity and may become more susceptible to disease or poor health. Outcrossing periodically and methodically can strengthen vigor in a herd by adding in unrelated genes. However, an outcross does not come without its price. When you breed two completely unrelated rabbits, their offspring will have a more 'muddy,' unpredictable gene pool, and you will lose some predictability and consistency in your herd. You may also introduce new health or structural issues that were not present in your original gene pool. Because of the unpredictability introduced when outcrossing, it is recommended that outcrosses only be made occasionally in a tightly line-bred herd to strengthen vigor and add specific new structural 'parts' that your pre-existing stock lacks.
A less well-known, but perhaps the most valuable method of breeding, is linebreeding. Linebreeding is the breeding of related animals, such as a sire to his daughter, or a brother to a sister. It can also sometimes refer to the breeding of cousins to cousins, half-siblings to half-siblings, or grandparents to grandchildren. This method of breeding is very useful because it solidifies good characteristics in a herd. Tightly line-breeding a herd can help make traits more consistent where there is still a considerable amount of variation in the breed. In addition, line-breeding will also produce less ‘surprise’ inferior rabbits than an outcross will, because the two rabbits are related and their offspring will be predictably very similar to their parents. The animals may develop in a more predictable way, making keeping and selling decisions easier, and you will have a better idea of what specific health issues your herd might be at higher or lower risk of producing.
Line-breeding is excellent for strengthening consistency, but with that consistency of strengthening good traits, it can also strengthen the consistency of faults. For example, if rabbits with poor crown definition are repeatedly linebred for many generations without selecting for better crown definition, the trait will become more 'fixed' in your herd and you will lose some QTL heterozygosity, making it harder and harder to correct. By out-crossing to a rabbit with excellent crown definition, you can re-introduce the desirable trait over several generations. Line-breeding is a fairly safe method to use, provided the breeder takes care to select for desirable traits and watch for genetic structural or health issues should they pop up.
So how should these three methods be applied by the average breeder? Generally speaking, careful linebreeding, punctuated by occasional outcrosses used for specific goals, is the most successful long-term method of producing high quality, healthy animals. It is the thoughtful consideration of the advantages and disadvantages of these three methods over the past few decades that created the diverse and unique rainbow of Holland Lops we are able to admire today.
“If rabbits bred like rabbits, I’d be a billionaire.” Another breeder of Holland Lop rabbits, shared this wisdom with me when I visited her barn to select a new doe. The rabbit I ultimately choose cost me $300. That may seem expensive, but, in truth, I wasn't buying a rabbit. I was buying nearly seventy years of carefully selected genetic codes that were passed on from one generation to the next as breeders strived to create the perfect Holland Lop rabbit. Methods of breeding such as crossbreeding, out-crossing, and line-breeding have been used to create the ideal Holland Lop. The fundamental difference between these methods lies in the relationship between the rabbits that are being bred. Because every breeder and every rabbit is different, there is much disagreement on what is the ‘correct’ way to use these methods.
Crossbreeding refers to mating rabbits of different breeds to create offspring that are drastically different from their parents. This method was used to create the Holland Lop when in 1951 Adrian de Cock crossed a Netherland Dwarf buck (male rabbit) with a French Lop doe (female rabbit). This essentially created a rabbit with the small size of the Netherland Dwarf and the floppy ears of the French Lop. This result could not have been achieved without crossbreeding. Crossbreeding can also help establish a new color gene into a breed. For example, Holland Lops were originally only solid-patterned, with no broken-patterned (solid color with white patches) rabbits available. Some Holland Lop breeders wished to create the Broken variety in the Holland Lop breed, and had to resort to crossbreeding because the gene for broken pattern simply did not exist in the Holland Lop breed. Holland Lops were crossbred with English Spots, and successfully created the Broken Pattern. However, the resultant Holland Lops did not have the rollback fur (fur that rolls back slowly when stroked the wrong way) that is called for in the ARBA breed standard. This resulted in a second crossbreeding between Broken Holland Lops and a breed known as the French Angora in order to regain the rollback coat. Breeders were able to recreate the rollback coat, but unfortunately the French Angora, being a wool breed, passed the recessive wool gene to their Holland Lop offspring. This meant that when two wool carrier Holland Lops were bred, approximately 25% of the resultant offspring had wool coats. These wooly Holland Lops were later developed into a new breed – the American Fuzzy Lop.
A key disadvantage of crossbreeding is that the rabbits are no longer ‘purebred.’ Unless the crossbreeding was farther back than the rabbit’s great-grandparents, the rabbit is considered a mixed breed. However, the animal may still be shown and even win, provided it visually looks like its breed. Another disadvantage is that because the progeny are mixed breed, they might be less desirable for other breeders to buy as show or brood animals. Crossbreeding without a clear and specific goal could risk a breeder's reputation, and it may introduce undesirable characteristics into the gene pool along with any desired benefits. While it is certainly possible to have success crossbreeding rabbits with clear and specific goals in mind, in most cases, there isn't much of a benefit, especially in popular breeds with quality animals and a large, healthy gene pool.
A safer method of breeding is outcrossing. Outcrossing is the breeding of two rabbits that are of the same breed but are from unrelated lines. This usually means they share none of the same rabbits in their pedigree. On the positive side, a good outcross can greatly strengthen weak areas in your herd. For example, I recently purchased a new Holland Lop buck. He is unrelated to my current rabbits, so would be considered an outcross. My current rabbits have excellent hindquarters but lack a wide ear base. In contrast, my new buck has less optimal hindquarters, but a very good ear base. When I outcross him to my rabbits, I can expect that a portion of his descendants could have great hindquarters and great bone density. Being able to produce those more superior rabbits is the true value of an outcross. Therefore, by some degree of random genetic chance, I can get some excellent offspring that have the advantages of both the outcross and my pre-existing stock. However, I could also produce rabbits with the disadvantages of both their parents, or even new, unexpected disadvantages. There are no guarantees, and outcrossing successfully may take several generations to successfully integrate a new line into your program. A breeder must keep these benefits and risks in mind when making the decision to outcross.
Outcrossing can also improve a herd’s vigor, or, its overall thriftiness and health. If a line of rabbits is bred only to other related rabbits for a long period of time, they lose some heterozygosity and may become more susceptible to disease or poor health. Outcrossing periodically and methodically can strengthen vigor in a herd by adding in unrelated genes. However, an outcross does not come without its price. When you breed two completely unrelated rabbits, their offspring will have a more 'muddy,' unpredictable gene pool, and you will lose some predictability and consistency in your herd. You may also introduce new health or structural issues that were not present in your original gene pool. Because of the unpredictability introduced when outcrossing, it is recommended that outcrosses only be made occasionally in a tightly line-bred herd to strengthen vigor and add specific new structural 'parts' that your pre-existing stock lacks.
A less well-known, but perhaps the most valuable method of breeding, is linebreeding. Linebreeding is the breeding of related animals, such as a sire to his daughter, or a brother to a sister. It can also sometimes refer to the breeding of cousins to cousins, half-siblings to half-siblings, or grandparents to grandchildren. This method of breeding is very useful because it solidifies good characteristics in a herd. Tightly line-breeding a herd can help make traits more consistent where there is still a considerable amount of variation in the breed. In addition, line-breeding will also produce less ‘surprise’ inferior rabbits than an outcross will, because the two rabbits are related and their offspring will be predictably very similar to their parents. The animals may develop in a more predictable way, making keeping and selling decisions easier, and you will have a better idea of what specific health issues your herd might be at higher or lower risk of producing.
Line-breeding is excellent for strengthening consistency, but with that consistency of strengthening good traits, it can also strengthen the consistency of faults. For example, if rabbits with poor crown definition are repeatedly linebred for many generations without selecting for better crown definition, the trait will become more 'fixed' in your herd and you will lose some QTL heterozygosity, making it harder and harder to correct. By out-crossing to a rabbit with excellent crown definition, you can re-introduce the desirable trait over several generations. Line-breeding is a fairly safe method to use, provided the breeder takes care to select for desirable traits and watch for genetic structural or health issues should they pop up.
So how should these three methods be applied by the average breeder? Generally speaking, careful linebreeding, punctuated by occasional outcrosses used for specific goals, is the most successful long-term method of producing high quality, healthy animals. It is the thoughtful consideration of the advantages and disadvantages of these three methods over the past few decades that created the diverse and unique rainbow of Holland Lops we are able to admire today.