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One of the most bandied about terms among Basset Hound
breeders today seems to be linebreeding. Despite its widespread use, however,
linebreeding is frequently misunderstood and miscommunicated; in fact, it is not
altogether uncommon for an outcrossed pedigree to be mistakenly viewed as
linebreeding by the novice. The present discussion defines linebreeding and how
we can more accurately describe our linebred litters.
LINEBREEDING AND INBREEDING: A FAMILY AFFAIR
INBREEDING and LINEBREEDING
involve the mating of animals within the same family. Breeding relatives is
used to cement traits, the goal being to make the offspring homozygous (pure)
for desirable characteristics. Homozygous dogs tend to be prepotent and produce
offspring that look like themselves (Walkowicz & Wilcox 1994).
Willis (1989) defines INBREEDING as the mating of
animals "more closely related to one another than the average relationship
within the breed." Inbred pairings would include brother/sister (the
closest form), father/daughter, mother/son and half-brother/half-sister.
LINEBREEDING involves breeding relatives other than the individual
parents or brothers and sisters. Typical linebred matings are grandfather/granddaughter,
grandmother/ grandson, grandson/granddaughter, great-granddaughter/great-grandson,
uncle/niece, aunt/nephew and cousin crosses. Linebreeding
is a less intense form of inbreeding. Because of their focus on a dog’s
potential genetic contribution, inbreeding and linebreeding are termed genetic
breeding systems.
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Figure 1 GENETIC
BREEDING SYSTEMS |
INBREEDING:
Matings involving parents and siblings.
Brother/Sister (the closest
form)
Father/Daughter
Mother/Son
Half-Brother/Half-Sister |
LINEBREEDING:
Matings involving relatives other than parents and siblings.
Cousins (have one or two
Grandparents in common)
Nephew/Aunt
Niece/Uncle
G. Granddaughter/G. Grandson
Grandson/Granddaughter
Grandfather/Granddaughter
Grandmother/Grandson
*Linebreeding past the 4th generation has little effect* |
OUTCROSSING:
The breeding of unrelated animals. Works best if one or both are inbred or
linebred.
(Matings involve unrelated animals.)
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HIGH |
Degree of Intensity |
LOWER |
DEFINITION:
For a dog to
be linebred there must be an ancestor in the pedigree that is common to both the
sire and the dam. Figure 2 illustrates
this concept. Kelly is linebred because the dog, Brahms, appears twice in the
sire’s side and once in the dam’s side of the pedigree.
COMMON MISCONCEPTION: A pedigree may show either the sire
and/or the dam to be linebred but no ancestor common to both the sire and dam.
This is outcrossing, not linebreeding (see Figure 3).
Similarly, because the same kennel prefixes (Windy, Hill,
Castle) are common to both the sire’s and dam’s ancestors, the newcomer may
mistakenly view the pedigree as linebreeding.
WHERE TO DRAW THE "LINE"?
Breeders do not always agree on what constitutes linebreeding,
with some feeling that common ancestors within the first five or six generations
is linebreeding. Willis (1989) indicates that the farther back linebreeding is
in a pedigree the less intensive it will be, pointing out that a dog appearing
12 times (out of a possible 32) in the 6th generation of a pedigree
would have a Coefficient of Inbreeding (CI) of only 1.8% (by comparison, a sire
to granddaughter cross has a CI of 12.5%). The CI tells us the proportion of
genes for which the inbred ancestor is likely to be homozygous, that is carrying
the same genes from each parent. (Remember that homozygous animals have a higher
potential for reproducing themselves.) In Willis’s (1992) view, a common
ancestor farther back than the 2nd or 3rd generation will
have little influence on the litter. Linebreeding beyond the fourth generation
has even less genetic impact.
HOW MUCH BANG WILL WE GET FOR OUR BUCK (OR BASSET!)
Several modern writers (Walkowitz & Wilcox 1994; Willis
1992, 1989; Onstott 1962) view linebreeding and inbreeding as essentially the
same and differing only in degree of intensity. Whether one considers inbreeding
and linebreeding to be the same or feels they are two distinct breeding systems,
quantifying the degree to which an animal is linebred (or inbred)
provides important information regarding its potential genetic contribution. As
Willis (1989) states: "When describing inbreeding [or linebreeding]
breeders often say their dog is inbred or linebred without further
qualification. This is a very inadequate description. We need to know which dog
the animal is inbred [linebred] to and the degree of inbreeding [linebreeding]."
Put another way, how much "bang" will we get from our linebreeding?
DESCRIBING YOUR BASSET’S LINEBRED PEDIGREE: READING,
WRITING AND A LITTLE ARITHMETIC!
Willis (1992) suggests that a concise yet meaningful way to
express the extent of linebreeding (inbreeding) is to number the generations of
the animal in question. The common ancestor(s) is assigned the generation
number as he/she appears in the pedigree. The parents are the first generation
(1), the grandparents are the second (2), great-grandparents are the third (3),
great-great-grandparents are the fourth (4) and so on. Figure 2 illustrates this
concept.
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FIGURE 2 LINEBREEDING
(1)
(2) (3) |
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FIGURE 3 OUTCROSSING
(Sometimes mistaken as linebreeding) |
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Kelly
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Sire
Neil |
Barry |
Brahms |
Rover |
Sire
Windy
Edward |
Castle
Prince |
Castle King |
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Nancy |
Castle Queen |
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Fanny |
Brahms |
Windy
Maiden |
Castle King |
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Zella |
Castle Queen |
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Dam
Belle |
Brahms |
Alert |
Dam
Hill’s
Emma |
Windy
Thomas |
Windy Will |
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Mary |
Hill’s Lisa |
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Raven |
Chime |
Hill’s
Mary |
Windy Will |
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Pam |
Brown’s Cora |
As previously stated, Kelly’s pedigree is an example of
linebreeding, with Brahms appearing on both the sire’s and dam’s side.
On the sire’s side Brahms appears twice in the third generation (3). We can
write this as 3.3. On the dam’s side, Brahms appears once in the second
generation (2) and this is written simply as 2. Willis has suggested the
following written and verbal formats for expressing the extent of
linebreeding in a pedigree:
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WRITTEN FORMAT |
VERBAL FORMAT |
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We would write:
"Kelly is linebred on Brahms 3.3/2. " |
We would say:
"Kelly is linebred on Brahms
three, three TO two." |
In the Written Format notice we separate the sire’s and dam’s
side of the pedigree by using a slash mark (think of a pencil making a
slash mark); in the Verbal Format the word "TO" is used to
separate the sire’s and dam’s side (think of talking "to"
someone). This verbal and written format tells us the dog on which Kelly is
linebred and the extent of the linebreeding. Smaller numbers indicate that a
dog is more closely linebred; larger numbers of 4 and above (Willis 1989)
indicate a lesser extent.
LINEBREEDING AND PEDIGREES: A FINAL CAVEAT
Linebreeding and inbreeding are essentially the same,
differing only in degree of intensity. (In Willis’s view, common ancestors
beyond the 2nd and 3rd generations will not greatly
influence the resulting litter.) We have described the ease with which an
animal’s extent of linebreeding may be expressed by means of written and
verbal models. Perhaps this format will be "adopted" by those Basset
Hound breeders whose interest lies in linebreeding. In addition to facilitating
the description of a linebred pedigree over the phone, it certainly provides
important information regarding the potential outcome of a breeding. In this
regard, two things bear repeating: (1) linebreeding (and inbreeding) are only as
viable as a breeder’s knowledge of basic genetics (a topic which will be
addressed in future columns) and (2) a linebred pedigree is only as valuable as
a person’s ability to determine the virtues and faults of the dogs it
contains. When we add the final ingredient of rigorous selection hopefully we
are on the way to producing better Basset Hounds!
REFERENCES
Onstott, K. 1980. The New Art of Breeding Better Dogs.
Howell, New York.
Walkowicz, C. and Wilcox, B. 1994. Successful Dog
Breeding. Howell, New York.
Willis, M.B. 1968. A simple method for calculating Wright’s
coefficient of inbreeding. Rev. Cubana Cienc. Agric. (Eng. Ed.) 2: 171-4.
Willis, M.B. 1989. Genetics of the Dog. Howell, New
York.
Willis, M.B. 1992. Practical Genetics for Dog Breeders.
Howell, New York.
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