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The Genetics of Coloration in Texas Longhorns: Part 4: Spotted, Lineback, Color-Sided, and White Park Patterns

[Part 1 | Part 2 | Part 3 | Part 4 | Part 5]

© David M. Hillis, Double Helix Ranch

Section of Integrative Biology, University of Texas, Austin, TX 78712

Texas Longhorns at the
Double Helix Ranch

This article is the fourth in a five-part series on the genetics of coloration in Texas Longhorn cattle. This article will be published in Texas Longhorn Trails, Volume 16, number 7 (October 2004). If you have comments or questions about this article, please e-mail me.

This article is intended for a general audience of Texas Longhorn breeders, rather than a technical audience. However, some scientific jargon is unavoidable, so if any of the terms are unfamiliar, please see the Glossary.

Over the past several months I’ve discussed how Texas Longhorns inherit the color of their coats. These colors include the various combinations of red and black pigments that produce the broad spectrum of colors observed in the breed. However, I haven’t said much to this point about the various patterns that result from a lack of any pigment. In other words, how are patterns that involve white hair produced?

Many people seem to think of cattle as basically white, with various colors added across the coat in different patterns. However, every Texas Longhorn has an underlying color (black, red, or wild-type), but may have additional genes that keep that color from being expressed on certain parts of the body. So, we should actually think of all Longhorns as colored, with some areas of color removed from the coat in different patterns (to produce white). Even Texas Longhorns described as “white” are not completely white, even though the colored hairs may be limited to the ears. The inheritance of the various patterns of white is not simple, and involves a number of different genes, all of which can act in combination to produce a multitude of patterns.

I’ve often heard Texas Longhorn breeders suggest that white coloration is dominant. That isn’t quite right, as mostly white animals are only produced if certain genes are present together in combination. However, several different genes (in the right combination) can produce a mostly white animal, and so it is true that white Longhorns are produced quite commonly, even from highly colored parents.

One gene that controls patterns of white coloration is known as the Spotted gene. There are three known alleles (forms of the gene) that occur in Texas Longhorns, and it is likely that additional alleles of the gene exist in the breed that have not yet been described. The form of the gene that was thought to be present in wild aurochs is abbreviated S+, and if an animal is homozygous for this allele, then it will be solid colored (if we ignore other white-producing genes for the moment). Another allele of this gene is abbreviated SP, and is called the lineback allele (the subscript P stands for Pinzgauer, the breed in which the allele was first described). The SP allele is incompletely dominant, meaning that a heterozygous SP/S+ animal will show some degree of the lineback pattern (similar to the pattern seen Figure 1), but a homozygous SP/SP animal will show much more of the white coloration (Figure 2). Longhorns that are heterozygous for the lineback and solid alleles usually show a small area of white coloration running from the topline across the rump and down to the belly, although the white may be restricted to the rump in some cases. In some animals that are heterozygous for the lineback allele, the white is barely noticeable, and the animal may even be described as “solid,” although small patches of white will be visible on the rump and tail.

The third allele for the Spotted gene that occurs in Texas Longhorns is the recessive s allele. Animals that are heterozygous for the lineback and spotted alleles (SP/s) exhibit the pattern seen in Figure 1. Animals that are homozygous for the s allele are spotted (Figures 3 and 4). However, the degree and size of the spotting varies widely, depending on interactions with other genes (e.g., compare Figure 3 and Figure 4). One of the genes that interacts with the Spotting gene produces the larger spots, as well as colored legs and head, seen in the bull in Figure 3 (I’ll discuss this modifying gene in more detail in Part 5 of this series).


Figure 1. A young Texas Longhorn cow (D-H Red Dawn) that is heterozygous for the lineback and spotted alleles at the Spotted gene (SP/s). Animals with this genotype show varying amounts of white coloration, although there is usually some white present on the topline, rump, and belly. Animals that are heterozygous for the lineback and solid alleles (SP/S+) exhibit a similar pattern, but without the spotting in the white areas.



Figure 2. A cow (Sweet Donna) that is homozygous (SP/SP) for the lineback pattern. Notice that there is much more white along the topline and belly compared to the cow in Figure 1. Note the solid coloration on the head, which helps distinguish this pattern from color-sided (compare to Figure 5).



Figure 3. A bull (D-H Shogun) that is homozygous for the recessive spotting allele (s/s). The exact pattern of spots produced by this gene is highly variable, and is modified by other genes. This bull’s sire (Overlord CP), grandsire (Emperor), and granddam (Kimco 5) were all homozygous for this gene as well, and each exhibited varying degrees of spotting.



Figure 4. This cow (Fairy Tail) is also homozygous for the recessive spotting allele (s/s), although the size and distribution of spots is considerably different from the bull shown in Figure 3. This cow is a daughter of Impressive, and her pedigree goes back to Measles 2849 on both sides. This Longhorn family often produces offspring with small spots.



A pattern that is often confused with the lineback pattern, but which has a completely different genetic basis, is known as the color-sided pattern (Figure 5). The color-sided and lineback patterns are superficially similar, but are produced by different genes. Solid animals are homozygous for the recessive allele (cs+) at the Color-sided gene (in addition to being homozygous for the S+ allele at the Spotted gene). Animals with one copy of the partially dominant color-sided allele (Cs) show some variant of the pattern seen in Figure 5, with an irregular border to the colored area, and typically a spotted or “lacey” face. The exact expression of the pattern is variable, and in black animals (with at least one copy of ED at the Extension gene), heterozygous Cs/cs+ animals may even appear to be blue roans. However, animals that are homozygous for the Cs allele are mostly white, with very small areas of coloration (usually on the ears and feet, as seen in Figure 6, but sometimes with small spots elsewhere on the body as well). This is the White Park or “flea-bitten” pattern that is common in Butler cattle. Not all Longhorns with this pattern are homozygous for the Cs allele, however, for the same basic pattern is also produced through various interactions of the Color-sided, Spotted, and Roan genes. The pattern of the cow shown in Figure 6 results from interaction among two of these three genes (in this case, the Color-sided and Spotted genes).


Figure 5. Comanche 22, a two-year old Butler bull with the classic color-sided pattern (note the dappled face and irregular border of the colored area). This same basic color pattern can be seen in this bull’s paternal lineage going back to Milby Butler’s bull Bevo.


The color-sided allele is common among Butler cattle, in part because two of the most famous Butler Longhorns, Bevo and Beauty, were both heterozygous Cs/cs+ for the Color-sided gene (and therefore both showed the color-sided pattern). Several of their famous offspring, such as Classic and Lady Butler, were homozygous Cs/Cs, and so showed the White Park or flea-bitten coloration, as did Lady Butler’s son by Bevo, Monarch 103. The color-sided gene is therefore quite common in Butler Longhorns, in large part because of the popularity of these lineages. In fact, the color-sided pattern of the Butler bull shown in Figure 5 is from a long line of mostly color-sided bulls that trace back to Bevo (Bevo to Classic to No Double to VJ Tommie to VJ Nestor to Comanche 22). Of these bulls, all were heterozygous Cs/cs+ (and therefore color-sided) except for Classic, who was homozygous Cs/Cs (and therefore mostly white).

Many breeders and buyers seem to discount the price of Texas Longhorns that are mostly white, apparently out of fear that they will produce mostly white offspring. However, white Texas Longhorns do not necessarily produce white offspring, depending on the genetic make-up of the dam and sire in the breeding. For instance, consider the cow shown in Figure 6 (L Brilliant Mary). As I mentioned above, the White Park pattern of this cow is the result of an interaction of two heterozygous genes (Color-Sided and Spotted). This means that despite her mostly white coloration, she can produce a very wide diversity of color patterns in her offspring, including solid, color-sided, and spotted. In addition, because she is homozygous for the recessive e allele at the Extension gene, she can produce red, wild-type (including brindle and other variants), or black (including grulla) calves, depending on which bulls are used with her. As this example demonstrates, some mostly white cattle (such as L Brilliant Mary) can produce a very wide diversity of colors and patterns in their offspring. So, for the breeder who likes color and pattern diversity, these cows can be highly desirable. Often, it is possible to determine the genotype of such cows by examining their ancestors and previous offspring.


Figure 6. L Brilliant Mary, a Texas Longhorn cow with the White Park pattern. Several different genetic combinations can produce this pattern (e.g., homozygosity of the Cs allele at the Color-sided gene, as well as various interactions among the Color-sided, Spotted, and Roan genes).


The diverse and interesting interactions of the Color-sided gene with other genes often confound breeders of Texas Longhorns. For instance, the interaction of the color-sided allele (when heterozygous) with black coloration to produce blue roans explains why some breeders have experienced difficulty trying to breed for the blue roan coloration. Roan coloration is also produced by yet another gene, called Roan (one of the subjects of Part 5 in this series). Therefore, roan-colored Longhorns can have several different genetic backgrounds, and so breeding for roan coloration is not necessarily as simple as breeding a roan bull with a roan cow. Many offspring of a blue roan bull (in which this color results from an interaction of the Color-sided and Extension genes) will be color-sided, flea-bitten, or solid colored. Next month, I’ll discuss an example of this type of mating to illustrate the complex interactions of the white-producing genes.

 

Want more detail? Please see the following papers:

Additional Reading and References

Hillis, D. M. 2004. The genetics of coloration in Texas Longhorns: Part 1: The basic colors. Texas Longhorn Trails 16(3):40-41.

Hillis, D. M. 2004. The genetics of coloration in Texas Longhorns: Part 2: Grulla, dun, and other reduced pigment patterns. Texas Longhorn Trails 16(5):76-77.

Hillis, D. M. 2004. The genetics of coloration in Texas Longhorns: Part 3: The wild-type color variants. Texas Longhorn Trails, September 2004.

Hillis, D. M. 2004. The genetics of coloration in Texas Longhorns: Part 5: Roan and brockling patterns. Texas Longhorn Trails, November 2004.

Joerg, H. et al. 1996. Red coat color in Holstein cattle is associated with a deletion in the MSHR gene. Mammalian Genome 7: 317-318.

Klungland, H. et al. 1995. The role of melanocyte-stimulating hormone (MSH) receptor in bovine coat color determination. Mammalian Genome 6: 636-639.

Lauvergne, J. J. 1966. Génétique de la couleur de pelage dex boivins domestiques. Bibliographia Genetica 20:1-168.

Olson, T. A. 1980. Choice of a wild-type standard in color genetics of domestic cattle. Journal of Heredity 71:442-444.

Olson, T. A. 1981. The genetic basis for piebald patterns in cattle. Journal of Heredity 72:113-116.

Olson, T. A. 1999. Genetics of Colour Variation. In The Genetics of Cattle (R. Fries and A. Ruvinsky, eds.). Pp. 33-53. CABI Publishing, Wallingford, United Kingdom.

Robbins, L. S. et al. 1993. Pigmentation phenotypes of variant extension locus alleles result from point mutations that alter MSH receptor function. Cell 72:827-834.

 

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