The Horse , everyone know this animal

Horse is herbivorous animal of the genus Equus in the order Perissodactyla. There are two subspecies in existence: domestic horses and wild horses. Wild horses have erect neck manes, very short forehead hairs, long tail hairs, and no spur hairs on their limbs. In summer, their upper bodies are light brown, reddish brown, or reddish ochre, and in winter, their backs are light brown. Domestic horses are divided into heavy horses, small horses, and miniature horses. Domestic horses have long limbs, strong bones, well-developed tendons and ligaments, hard hooves, and a variety of fur colors, mostly chestnut, blue, and black. They have well-developed sweat glands and strong teeth for chewing.

Based on the natural environment of the horses’ origins, as well as differences in appearance and performance, horses can be divided into grassland species, desert species, mountain species, and forest species. Grassland species are distributed in vast grassland areas; desert species live in dry desert areas; mountain species are good at walking on mountain trails; and forest species live in forest areas with a relatively cold climate. Horses reach sexual maturity at 4 years old, mate in June, and give birth in April or May of the following year. The average lifespan of a horse is 30 to 35 years, but can reach up to 60 years.

Fossil research

Fossil research has confirmed that the ancestor of the horse family, Eocene hippocampus, first appeared in North America 55 million years ago. Subsequently, changes in topography, climate and ecology occurred in nature, and open inland plains emerged. Equus gradually adapted to these changes and eventually went through the evolutionary stages of Eohippus, Mesohippus, Protohippus, Pliohippus and Euhippus. [16 ]As early as 6,000 years ago, China domesticated wild horses as livestock. For a long time thereafter, horses became one of the main means of transportation. Horses have a well-developed nervous system, keen hearing and smell, and strong light sensitivity, and can see surrounding objects at night. The well-developed sense of smell, sensitive hearing, and good light sensitivity enable horses to form a strong memory, hence the saying that “old horses know the way”.

Evolution

Fossil research has confirmed that the ancestor of the horse family, Eocene horses, appeared in North America 55 million years ago. They were the size of foxes, fed on juicy young leaves, had four toes on their front feet and three toes on their hind feet.

Subsequently, the natural topography, climate and ecology changed, and open inland plains emerged. The evolution of horses gradually adapted to these changes. The evolution of horses went through major development stages, including Eohippus, Mesohippus, Protohippus, Pliohippus and Euhippus. Its main evolutionary characteristics are: the body becomes larger; the height increases from the original 40cm to more than 120cm; the toes evolve from three or four toes to a single toe (single hoof) to facilitate running; the teeth change from a low-crowned cusp structure to a high-crowned, hard tooth, wide and wrinkled tooth surface structure to facilitate eating hay; the brain capacity increases.

Eohippus:

It has a short head and neck, a curved back, and is about 40 cm tall. It has four toes on its front feet, but only three toes on its hind feet. The ulna of its front limbs and the fibula of its hind limbs are slender but still separate. Its molars are short, with low crowns and caruncle-like protrusions. It lives in shrubs and feeds on fresh, juicy leaves and soft grasses. 

Middle horse:

slightly larger in size, about 50 cm tall, with only three toes on both front and rear limbs, with the middle toe being particularly developed to support most of the body weight. It still lives in the forest and can run fast on hard ground. 

Protohorse:

An important intermediate transitional form, the living environment shifted to grasslands, feeding on coarse grass. The body size increased, the teeth became harder, the skull volume increased, and the face became longer. Each foot still had three toes, and only the middle toe touched the ground when walking. 

Pliocene:

About 12 million years ago, the body height was about 100 cm. Each limb still had only three toes, with only the middle toe visible, and the second and fourth toes on both sides were twig-like remnants.

By comparing with ancient DNA sequencing data, it was found that Przewalski’s horse is not the ancestor of the domestic horse. Its divergence time is between 38,000 and 72,000 years, which is much earlier than the domestication of the domestic horse. The ancestor of the genus Equus diverged between 4 and 4.5 million years ago. The horse population has fluctuated greatly in the past 2 million years. It was also found that pathways related to immunity and olfaction were greatly selected during the evolution of the horse. 

Domestication

According to a large amount of evidence published in Science in recent years about the Botai culture in northern Kazakhstan, horses were domesticated in the Eurasian steppes at least 5,000 years ago during the Bronze Age. The earliest purposes of horse domestication may have been three: one was to keep excess hunting horses as a source of food, the second was to use them for labor and archery, and the third was to use them for sacrifice or viewing.

Appearance feature

The body is well-proportioned, with long limbs, a well-developed third toe and hooves, and the second and fourth toes are degenerate, leaving only degenerate metacarpals and metatarsals. The limbs are highly specialized, with very short humerus and femur, very long radius and tibia, and both ulna and fibula are regressed. The third toe is well-developed, with very long metacarpals and relatively short phalanges, and a single hoof. The cheek teeth have high crowns; the enamel layer of the upper molars is finely folded.

Heavy breeds weigh up to 1,200 kg and are 200 cm tall; small breeds weigh less than 200 kg and are only 95 cm tall, and the so-called miniature pony is only 60 cm tall. The head is straight and long, and the ears are short. The limbs are long, the bones are solid, the tendons and ligaments are well developed, and the cicada (commonly known as night eye) with traces of palm pillows is attached. The hoof is hard and can run quickly on hard ground.

The coat color is complex, mostly chestnut, blue and black; the coat is shed once in spring and autumn. The sweat glands are well developed, which is conducive to regulating body temperature. It is not afraid of severe cold and heat and can easily adapt to new environments. The chest is deep and wide, the heart and lungs are well developed, suitable for running and intense labor.

Esophagus

The esophagus is narrow, the stomach is single, and the large intestine, especially the cecum, is abnormally developed, which helps digest and absorb roughage. There is no gallbladder, and the bile duct is well develop. The teeth have strong chewing power. The gap between the incisor and the molar is call the bit, which is place when the bit is install to facilitate driving. The age can be determine by the number, shape and wear of the teeth. The hearing and smell are keen.

The distance between the two eyes is large, and the overlap of the visual field is only 30%, so the judgment of distance is poor; at the same time, the eye’s focal adjustment ability is weak, and only a blurry image of an object more than 500 meters away can be formed, but the shape and color of close objects can be well distinguished, and this is the only animal that can distinguish colors. The head and neck are flexible, and the visual field of both eyes is 330° to 360°.

There is a layer of film on the outer layer of the retina at the fundus, which is highly sensitive to light and can see surrounding objects at night. Horses are easy to train. Through the sense organs such as hearing, smell and vision, they can form a strong memory. The average lifespan is 30 to 35 years old, and the longest can reach more than 60 years old. The working age is 3 to 15 years old, and some can reach 20 years old.

Living habits

Wild horses like to live in groups, usually consisting of a male horse, several female horses, and their offspring. Each group has a clear range of activities and migrates at a speed of 5-10 kilometers per day. Wild horses feed on Achnatherum splendens, Haloxylon ammodendron, reeds, and red willow in the desert, and in winter they can dig through the snow to find dry grass. After eating, individuals in the group often clean each other’s skin, gently licking each other’s toenails, shoulders, backs, buttocks, etc. Sometimes they also take care of themselves, such as rolling around, brushing themselves, and dispelling mosquitoes and flies. Wild horses communicate through sounds, smells, and behaviors such as pursing their ears, digging the ground, and chewing

Reproduction

Horses, donkeys and zebras are originally three independent species, and reproductive isolation has occurred. But interestingly, hybrids of horses and donkeys and zebras can produce offspring. Mules are hybrids of horses and donkeys, divided into horse mules (donkey ♂×horse ♀) and donkey mules (horse ♂×donkey ♀). Male mules are generally consider to be infertile, but there are reports of female mules giving birth to foals, and reports that the conception rate of horse mules is significantly higher than that of donkey mules (about 7 times).

By comparing the karyotypes of horses and donkeys, it is speculated that a reproductive mule may form a hexavalent during meiosis. Przewalski’s wild horses and domestic horses have undergone a Robertsonian translocation that leads to differences in their karyotypes. The first generation of their hybrids will form trivalents during meiosis, which can form mature germ cells and reproduce offspring, but its mechanism has not yet been resolve.

Variety

Commonly used classification methods include biological classification, animal husbandry classification, and cold and hot bloodline classification

Biological classification

Based on the natural environmental conditions of the horses’ origins, as well as differences in their appearance and performance, horses can be divid into grassland species, desert species, mountain species, and forest species.

Grassland species : distributed in the vast grassland areas of the world. As they live in the grasslands day and night for a long time and lead a herd life, they are fully train in the natural environment, are hardy and have strong adaptability. They are strong and sturdy, with a long, deep and broad body, short and thick limbs, thick and dense fur, well-developed long hair, strong feeding and digestion ability, and strong character, such as Mongolian horses and Kazakh horses .

Desert horses : Horses that live in dry desert areas. They are relatively small in build, with fine, dry skin, thin fur, narrow chest and small abdomen. Horses lively in temperament, have less long hair on their manes and tails, have a fast metabolism, and move at a faster speed. They are mostly like riding horses, such as the Arabian horse and the Akhal-Teke horse. ^[1]

Mountain breeds : They are sturdy, small in size, have strong limbs, are agile, have a quick temper, and are good at walking on mountain trails, such as the Baise horse , Ningqiang horse , and Kabajin horse . 

Forest horses : horses that live in forests with a cold climate. They are generally small in size but relatively heavy. They have deep and wide trunks, short and thick limbs, well-developed stomachs and intestines, full muscles, and thick and dense fur with more long hair, such as the Yakut horse and the Estonian horse.

Animal Husbandry Classification

Horses are classified according to their height, size, use, body shape, and beneficial economic characteristics. According to body shape, they can be divid into three categories: riding type, pulling type, and dual-purpose type. 

Riding type : such as thoroughbred horses, Arabian horses, etc. 

Draft horses : such as the Ardennes horse, Belgian heavy draft horse, and Belgian heavy draft horse. 

Three River Horse

Dual-purpose type : such as Sanhe horse. Its appearance is between riding type and pulling type, but it also has its own unique characteristics. In practical applications, the classification of animal husbandry is applicable to the classification of improved breeds. Local breeds that have not undergone specialized breeding are dual-purpose in body shape, but they are not exactly the same as the dual-purpose type of bred breeds

Hot and cold bloodline classification

Cold-blooded and hot-blooded do not refer to the temperature of a horse’s blood, but rather to the degree of selection and breeding of the horse breed and the type of temperament of the horse. The classification of cold-blooded, hot-blooded and warm-blooded breeds was first use in Europe to classify horse breeds, and is now widely use around the world.

Cold-blooded : Generally a general term for draft horses that originated in Europe and are descendants of prehistoric forest horses. These horses are large, gentle but slow to react, with a medium or low-hard temperament. They are mainly use for farming or transportation. Examples include the Ardennes horse and the Soviet heavy draft horse. 

Hot blood : mainly refers to light horse breeds that are highly bred, strong, and purebred. Such as Arabian horses, Akhal-Teke horses, and thoroughbred horses. 

Hanoverian Horse

Warmblood : Tall and docile; neither as pure and refined as warmbloods, nor as stout and slow as coldbloods. Warmblood horse breeds can be divide into purebred and half-blood breeds. Half-blood breeds, or hybrid breeds, are mainly bred by crossbreeding warmbloods with other breeds. Some warmblood horse breeds are bred by crossbreeding coldbloods with thoroughbreds and Arabians. Warmblood horses are the most popular equestrian horses. Examples include the Hanoverian horse , Holsteiner horse, and Dutch warmblood horse.