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The silver or silver dapple (''Z'') gene is a dilution gene that affects the black base coat color. It will typically dilute a black mane and tail to flaxen, and a black body to a shade of brown or chocolate.〔("Horse coat color tests -Silver Dilution" ) from the UC Davis Veterinary Genetics Lab〕 It is responsible for a group of coat colors in horses called "silver dapple" in the west, or "taffy" in Australia. The most common colors in this category are ''black silver'' and ''bay silver'', referring to the respective underlying coat color. Mature black silvers typically have sooty white or silver manes and tails with a flat, non-fading, dark grey or grey-brown body coat. The body coat frequently exhibits dapples, rings of lighter-colored hair. Mature bay silvers retain their reddish bodies, though the presence of small amounts of silver often gives them a chocolate appearance. The mane and tail are usually a sooty silver, darker at the roots, and the legs are usually a flat, brownish-grey mottled with silver. The hair around the eyes and muzzle may also show signs of silvering. Silver dapple foals can be difficult to identify, but commonly have a pale, wheat-colored body coat, white eyelashes, and hooves with tapering vertical stripes. These characteristics fade over time. Red-based horses, such as chestnuts and chestnuts with other dilution factors (such as palominos, and cremello) may carry the silver dapple gene, and may pass it on to their offspring, but will not express the gene in their own body color.〔 ==Silver mimics== * Gray: While gray horses grow progressively lighter, silver dapples often darken with age. A silver dapple masked by gray (i.e. carries both genes and, because gray is a dominant gene, becomes white with age) may be identified by use of DNA testing. * Liver chestnut: Silver dapples, especially bay silvers, are frequently misidentified as liver chestnuts or flaxen chestnuts. Flaxen manes and tails in chestnuts tend to have honey or red tones, while the pale manes and tails of silver dapples are soot-toned and darker at the roots. Liver chestnuts also lack the grey-brown dappling on the lower legs. The darkest liver chestnuts often have a kind of marbling on the lower legs, though this hair, too, should show red or yellow tones. Overall, chestnuts of all shades have red-yellow character to their coats, while silver bays recall grey-brown. Knowledge of the pedigree of the horse in question is often useful: two chestnut-based parents cannot produce a silver bay or silver black. DNA testing can be used in the most difficult cases. * "Sooty" palomino: Dark palominos may be hard to distinguish from silver dapples, particularly if the mane or tail of a palomino contain streaks of silver. A true palomino, with a red-based coat, will exhibit yellow or gold tones; a silver horse, in contrast, is by definition black-based and exhibits gray, black or brown undertones. A sooty palomino, like other creme dilutes, may have brown eyes a shade lighter than average, but this is not true of silver dapples. When actual color is in question, pedigree information or a DNA test can help clarify matters. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「silver dapple gene」の詳細全文を読む スポンサード リンク
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