White horse eating grass in 4K

White horse eating grass in 4K - White horses are born white and stay white throughout their life. White horses may have brown, blue, or hazel eyes. "True white" horses, especially those that carry one of the dominant white (W) genes, are rare. Most horses that are commonly referred to as "white" are actually "gray" horses whose hair coats are completely white.[1]

White horses have unpigmented skin and a white hair coat. Many white horses have dark eyes, though some have blue eyes. In contrast to gray horses which are born with pigmented skin they keep for life and pigmented hair that lightens to white with age, truly white horses are born with mostly white skin and white hair. Some white horses will have partial pigmentation in their skin and hair, which may or may not be retained as they mature, but if they lighten, unlike grays where only the hair becomes white, in a true white horse both skin and hair lose pigmentation.



White colorings, whether white markings, white patterns or dominant white are collectively known as depigmentation phenotypes, and are all caused by areas of skin that lack pigment cells (melanocytes).[2] Depigmentation phenotypes have various genetic causes, and those that have been studied usually map to the EDNRB and KIT genes. However, much about the genetics behind various all-white depigmentation phenotypes are still unknown.



Dominant white[edit]



The genetics behind this white Thoroughbred, and her white family members, are not yet understood.

Main article: Dominant white

Dominant white is best known for producing pink-skinned all-white horses with brown eyes, though some dominant white horses have residual pigment along the topline. Dominant white is, as the name implies, a genetically dominant color. At least one parent must be dominant white and it does not "skip" generations because it is not recessive. Nonetheless, new variations or mutations producing dominant white do occur spontaneously from time to time. Dominant white is rare, but has occurred in many breeds. It has been studied in Thoroughbreds, Arabian horses, the American White horse and the Camarillo White horse. There are 11 identified variants of dominant white, each corresponding to a spontaneously-white foundation animal and a mutation on the KIT gene. No horse has been identified as homozygous dominant white, and researchers have suggested that at least some forms of dominant white results in nonviable embryos in the homozygous state. While homologous mutations in mice are often linked to anemia and sterility, no such effects have been observed in dominant white horses. Dominant white horses typically have white noses that can be subject to sunburn.



Sabino-white[edit]

Main article: Sabino horse

Sabino-white horses are pink-skinned with all-white or nearly-white coats and dark eyes. They are homozygous for the dominant SB1 allele at the Sabino 1 locus, which has been mapped to KIT.[3] Without a DNA test, Sabino-white horses are indistinguishable from dominant white horses. The Sabino1 allele, and the associated spotting pattern, is found in Miniature horses, American Quarter Horses, American Paint Horses, Tennessee Walkers, Missouri Fox Trotters, Mustangs, Shetland Ponies, and Aztecas.[4] Sabino 1 has not been found in the Arabian horse, Clydesdale,[3] Thoroughbred, Standardbred horse, or Shire horse. The Sabino 1 allele is not linked to any health defects, though sabino-whites may need some protection from sunburn. Horses with only one copy of the Sabino1 gene usually have dramatic spotting, including two or more white legs, often with white running up the front of the leg, extensive white on the face, spotting on the midsection, and jagged or roaned margins to the pattern.[3]

Read more on: link



russia, europe, united states, putin, speech, talk, talks, about, 2013, 2014, 2015, 2016, russian, great, english, conference, subtitle, event. big, german, украина, пресс-конференция, ху*ло, крым, путин ху



----------------

Visit my blog: http://donaldsharev.blogspot.com

Visit my channel: http://youtube.com/donaldsharev

SUBSCRIBE:



twitter: https://twitter.com/donaldsharev

tumblr: http://donaldsharev.tumblr.com/

----

Thanks for watching!

Post comment, share, like and tell me what you think!

- Donald.



http://www.ask.com/  http://vk.com/

http://www.yandex.ru/  https://twitter.com/

http://www.liveleak.com/  http://www.wykop.pl/

http://www.bing.com/  https://www.tumblr.com/

http://www.reddit.com/  http://www.google.com/

https://www.pinterest.com/  https://www.facebook.com/