28 Oct 2010
Coat Color Genetics: Cremello, Perlino, Dun, Grullo & Roan
The cremello carries two cream dilution genes and two red genes. Technically, a cremello is a double diluted sorrel or chestnut. These horses are genetically sorrel or chestnut. A cremello will not have any black genes. The foal usually receives one cream dilution gene from a parent that is a palomino, buckskin, cremello or perlino. A parent may also be brown or black but has passed on the cream dilution. Crossing two cremellos will always produce cremello. Cremellos crossed with chestnut or sorrel will produce palomino. A cremello crossed with bay should produce buckskin, assuming the bay passes on the black points. You can never produce a bay, sorrel or chestnut if you cross with a cremello.
The perlino carries two cream dilution genes as well. These are inherited from either a palomino or buckskin parent. The perlino must have one black gene and two cream dilution genes. Crossing two perlinos will produce a perlino. Crossing a perlino with a cremello will produce perlino or cremello every time. Perlino crossed with sorrel or chestnut will produce palomino or buckskin. Perlinos crossed with bays produce buckskin about seventy-five percent of the time. If neither parent passed on the black gene, the foal will be palomino. Perlino crossed with any other color will produce a cream diluted color every time. The foal will not necessarily be double diluted, because the perlino can only pass on one cream gene. Crossing a perlino with a bay, sorrel or chestnut will never produce those colors.
To get a dun of any color, one of the foal’s parents must pass on a dun dilution gene. The parent can be a dun, red dun or grullo. The base of the red dun is sorrel or chestnut. The red dun will never have black points. The dun gene produces the dorsal stripe and zebra striped legs. Hint: Just because a horse has a dorsal stripe, it does not mean the horse is a dun. A dun must have the zebra striped legs as well. Buckskin is not a dun. A palomino, however, can have the zebra stripes and a dorsal stripe if the dun dilution gene is passed on. A red dun has two dun dilution genes. The dun can also express the roan gene.
A grullo is produce as an affect of the dun gene on a black base. The grullo does not carry the agouti gene. Some grullo will carry the cream dilution gene in addition to the dun dilution gene. A grullo can produce both a dun and cream dilution foal. So, they can produce either palomino or buckskin. The cream gene can often hide in the grullo the way it does in the bay and black. A grullo will pass on the dun gene every time, regardless of the color of the other parent. It is also possible for a grullo to carry the roan gene.
The roan gene is inherited from at least one parent. The roan gene is not associated with any other base colors. The gene simply affects the genes that the horse has. For example, a red roan is a sorrel or chestnut that expresses the roan gene. A bay roan is a bay that expresses the roan gene and a blue roan is a black that expresses the roan gene. A roan has white hairs scattered throughout the base coat. The basic colors are inherited normally, but the foal must receive the roan gene from at least one parent.