About Capra hircus Linnaeus, 1758
The domestic goat (Capra hircus Linnaeus, 1758) has distinct size variation across breeds. Adult weight ranges from over 140 kg (310 lb) for males (bucks) of large breeds like the Boer, down to 20 to 27 kg (44 to 60 lb) for females (does) of smaller breeds. Different strains or bloodlines within the same breed can also have different recognized standard sizes. At the smallest end of the size range are miniature breeds such as the African Pygmy, where adult individuals stand 41 to 58 cm (16 to 23 in) at the shoulder. Most goats naturally have two horns, with shape and size varying by breed. While rare genetic occurrences of polycerate goats (with up to eight horns) have been recorded, this trait is very uncommon. Unlike cattle, goats have not been successfully bred to be reliably polled (naturally hornless), because the genes that determine sex and the genes that determine horn presence are closely linked. Breeding two genetically polled goats produces a high number of intersex offspring, which are typically sterile. Goat horns are made of living bone covered by keratin and other proteins, and are used for defense, establishing dominance, marking territory, and thermoregulation. Both male and female goats can have beards, and many goat types (most commonly dairy goats, dairy-cross Boers, and pygmy goats) can have wattles, with one wattle dangling from each side of the neck. Goats have horizontal, slit-shaped pupils. This pupil shape lets them see well in both night and day, gives them a wide field of vision to detect predators on either side, and prevents them from being dazzled by overhead sunlight. Goats do not have tear ducts. Goats are ruminant even-toed ungulates, with a four-chambered stomach made up of the rumen, reticulum, omasum, and abomasum. Female goats have an udder with two teats, which differs from cattle that have four teats. The Boer goat is an exception, as it can sometimes have up to eight teats. Goats are diploid, with two sets of 30 chromosomes. Goats are naturally curious and agile, able to climb and balance in precarious locations. They are the only ruminant that regularly climbs trees. These traits make them notorious for escaping enclosures, as they constantly test fences; goats almost always escape if a fence can be overcome. Some studies have found goats to be as intelligent as dogs. When grouped together, goats show less herding behavior than sheep. When grazing undisturbed, they spread out across a field or range, rather than feeding side by side like sheep do. When nursing their young, goats leave their kids separated (a behavior called "lying out") rather than grouped together, as sheep do. Goats generally turn and face an intruder, and bucks are more likely to charge or butt humans than male sheep (rams) are. A 2016 study found that goats attempt to communicate with people in the same way as other domesticated animals like dogs and horses, and will look to a human for help when faced with a new, modified challenge. Goats reach puberty between three and 15 months of age, depending on breed and nutritional status. Many breeders prefer to delay breeding until a doe reaches 70% of her adult weight, but this schedule is rarely possible in extensively managed open-range herds. For Swiss and northern breeds, uncastrated males (bucks) enter rut (breeding season) in the fall, matching the females' fall heat cycles. Bucks of equatorial breeds may have seasonal reduced fertility, but like does they are able to breed at any time of year. Rut is defined by decreased appetite and obsessive focus on does. A buck in rut performs flehmen lip curling, and urinates on his forelegs and face. Sebaceous scent glands at the base of the buck's horns contribute to his odor, which is important for attracting females; some does will not mate with a buck that has had its scent glands removed. Goat gestation is approximately 150 days long. Twins are the most common birth outcome, with single and triplet births also common. Larger litters of four, five, or even six kids occur less frequently. Goat birth is called kidding, and it generally proceeds without complications. Just before kidding, a doe will develop a sunken area around her tail and hip, and breathe heavily. She may look anxious, become restless, and show increased affection for her keeper. Goat mothers often eat the placenta after birth, which provides much-needed nutrients, helps stop bleeding, and follows the same behavior seen in wild herbivores like deer that reduces the chance predators are attracted by birth scent. Freshening, when a doe begins milk production, usually happens at kidding, though it is also relatively common for unbred dairy doelings to produce milk. Milk production varies based on a doe's breed, age, overall quality, and diet. Dairy goats generally produce between 680 and 1,810 kg (1,500 and 4,000 lb) of milk over a 305-day lactation period. On average, a good quality dairy doe produces at least 3 kg (6 lb) of milk per day while she is lactating. First-time milkers may produce less, though exceptional individuals can produce as much as 7 kg (16 lb) or more. After lactation, the doe will "dry off" (stop producing milk), typically after she has been bred again. Occasionally, unbred goats that are continuously milked will continue lactating beyond the typical 305-day period. Male lactation sometimes occurs in goats. Goats are used to produce milk, specialty wools, meat, and goatskin. Some charities give goats to impoverished people in low-income countries, based on the idea that providing useful productive assets alleviates poverty more effectively than cash. However, the total cost of obtaining and distributing goats can be high. Some national militaries use goats to train combat medics. In the United States, goats became the main animal species used for this purpose after the Pentagon stopped using dogs for medical training in the 1980s. Though modern training mannequins effectively simulate human body function, trainees report that working with live goats creates a sense of urgency that only real-life trauma can provide. This practice has sparked strong public outcry from animal-rights groups.
