Bloodlines and color

This page is for the person who wants to send a mare, buy a foal, or check a cross. It explains the numbers this barn actually uses. It is a reading of public registry facts and of ordinary horse-color genetics. It is not a DNA report, and it is not a promise about a particular foal.

The names behind Samson

Rocky Mountain Horses were shaped in eastern Kentucky. The stallion Tobe, owned by Sam Tuttle, is the horse most of the modern registry traces to. Samson's breed reaches Tobe several times in four generations, which is normal in this breed and is why his inbreeding coefficient is 12.40%.

Four names on the stud listing do the real work:

• Broken Bone's Sam's Son, the sire. Chocolate, 1989, by Sewell's Sam out of Sewell's Beauty. Both of those parents are by Tobe.
• Sewell's Sam, bred by Sam Tuttle in 1975. Chocolate. This is the "Sewell Sam" line the stud page names.
• Maple's Squirrel, 1973, black, by Tobe out of Goodpastures Maude. He sired Samson's dam.
• Yankee (Ragtime), 1971, bay, by Tobe. He sired Red Gail, the dam of Samson's dam.

Latte lowers the pressure. Her own coefficient is 3.52%. She still meets Samson at Maple's Squirrel, so their foals, including Milton, are recorded at 9.67%, not at zero. Layla, whom we rehomed, was the lower figure at 1.16%, but her sire's sire is a son of Broken Bone's Sam's Son, so Everett Hemlock is a linebreeding at 7.36%. BB's Music Maker sits at 14.41%, and her sire is published at 26.56%. DJ's Velvet, Val, is 12.18% and already carries Broken Bone's Sam's Son as her dam's sire. Lacey, 3BF Midnight Lace, sits at 6.58%. She is black, 15 hands, by the chocolate roan FHF Wesley Union, and Sewell's Sam is still in that sire line. Low inbreeding and "no Sam blood" are not the same sentence.

How to read a coefficient

The percentage in the RMHA database is an inbreeding coefficient: the chance that both copies of a gene in this horse trace to the same ancestor. It is one published number. A closed gaited breed that funnels through Tobe will show double-digit figures on horses that are still sound, gaited, and useful. Use it to compare crosses inside this barn. Do not use it as a verdict by itself.

Silver

Silver (gene symbol Z) dilutes black hair. On a bay horse it makes a silver bay: the body stays reddish, the mane, tail, and points go pale. On a black horse it makes the chocolate-and-flaxen color the breed is known for. It does nothing visible to red hair, which is why a chestnut can carry silver without showing it. Samson is published as EE, so he does not sire chestnuts.

His test is ZZ, two copies of silver. The stud page prints Zz, one copy, and that printing is wrong. A ZZ stallion gives every foal a silver allele. Put to a mare with no silver, the foal is Zz, which laboratories often write Z/N. Samsons Legacy and Samsons Silver Mocha are both Z/N, which is the result that mating produces. Our rule, written into the breeding contract, is that we breed Samson to non-silver mares so we do not make a ZZ foal. A mare owner who wants to book him has to be able to say, honestly, that the mare is not silver and is not known to carry it. Phenotype is not enough on a chestnut. The UC Davis Veterinary Genetics Laboratory silver test is the usual way to check a horse whose color hides the gene. What ZZ and Zz mean for the eye is on the research page.

Black, bay, and cream

EE means both extension alleles are black. Every Samson foal gets an E from him, so none of them are chestnut. Aa means he carries one agouti allele. When he passes A, the foal can be bay-based if the rest of the genotype allows it. When he passes a, the foal is black-based unless the mare supplies A. That is why his foals come both silver bay and silver black.

Cream is Latte's contribution. Buckskin is bay plus one cream. Her sire is perlino, so the cream has a source. Samson is not a cream horse. Half of Latte's foals by him are expected to inherit cream. Silver buckskin, which Milton is, is bay plus cream plus silver. Silver bay, which King is, is bay plus silver and no cream.

Dun is a separate gene. Firefox is a silver dun and his dam, DJ's Velvet, is grullo. Samson's published genotype does not include dun. Do not expect dun from a Samson foal unless the mare brings it.

Where to click

Every horse page on this site links to the RMHA breed record for the five-generation chart. Samson's nationwide foals are one list: the offspring page. The association's sales copy for the stallion is the stud entry, repeated in plain fields on this site's stud page. Color tests and eye findings belong to the laboratories and the veterinarians, not to a paragraph on a ranch website.