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What the sources say

Domestic YakBos grunniens

Every figure, record and mechanism on the Domestic Yak profile was written from a source, and this is the working table behind it: 37 claims checked word for word against these sources. The left column is what the page says. The right column is the source's own words, copied, not paraphrased; a ... marks a cut and[brackets] an insertion. Open any source and check it yourself.

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Source
01

Jing et al. 2022

Jing et al. (2022). The adaptive strategies of yaks to live in the Asian highlands. Animal Nutrition.

The page saysOversized heart and lungs
The source saysThe size of the heart and lungs of yaks are substantially larger than cattle.Note: tagline
The page saysup to 5,000 m high
The source saysraised at altitudes between 3,000 and 5,000 m above sea levelNote: tagline
The page saysAsian highlands, 3,000 to 5,000 m above sea level
The source saysraised at altitudes between 3,000 and 5,000 m above sea level across the Asian highlandsNote: stats.habitat
The page saysForbs and low herbage, grazed with the lips
The source saysgraze forage using the labia oris , which minimizes exposure of the tongue to the cold environment, as well as enabling them to consume low herbagesNote: stats.diet
The page saysIn one study of grazing yaks, they consumed forbs throughout the year, but especially during the winter.
The source saysDing and Long (2010) used herbage N-alkanes to identify the main dietary components of grazing yaks in a transhumance grazing system, and the results indicated that forage consumed by yaks varied with season. Yaks consumed forbs throughout the year, but especially during the winter.Note: body: scoped to the one study the review reports
The page saysa heart that weighs 1.18% of body weight, against 0.39% in cattle
The source saysHeart weight in yaks is 1.18% of body weight as opposed to 0.39% in cattleNote: stats.superpower
The page saysNot Evaluated
The source saysthere are approximately 16 million domestic yaks and 15 to 20 thousand wild yaks in the worldNote: stats.conservationStatus. The page speaks of the domestic yak as a domestic animal, so no Red List category applies. The prefetch's Red List DOI (taxon 2892, 2016) is Bos mutus, the wild yak (Vulnerable), and is not cited. GBIF had no category for this name. Precedent llama, goat, domestic-cat: no IUCN reference. The quote's 'approximately' belongs to the herd count, not to the status.
The page saysPeople raise the yak (Bos grunniens) 3,000 to 5,000 m above sea level in the highlands of Asia.
The source saysThe yak ( Bos grunniens ), an indigenous herbivore raised at altitudes between 3,000 and 5,000 m above sea level across the Asian highlands
The page saysA yak has 15 chest vertebrae, one more than a cow, which makes its chest cavity bigger and leaves room for a large heart and lungs.
The source saysYaks have 15 thoracic vertebrae, one more than cattle, which increases the volume of the thoracic cavity and provides ample space for the large heart and lungs
The page saysA yak's heart weighs 1.18% of its body weight, where a cow's weighs 0.39%.
The source saysHeart weight in yaks is 1.18% of body weight as opposed to 0.39% in cattle
The page saysYaks have a greatly diminished response of this kind.
The source saysyaks have a greatly diminished hypoxic pulmonary vasoconstrictive response, which cattle do not have, when exposed to low air oxygen contentNote: paraphrase of the pulmonary vasoconstriction point; the body explains the term in its own words
The page saysYaks keep a high level of foetal haemoglobin throughout life, while it is generally present in other mammals for only 6 to 7 months after birth.
The source saysyaks maintain a high level of foetal haemoglobin throughout life; whereas, it is generally present in other mammals for only 6 to 7 months after the birth
The page saysThis form of haemoglobin, the blood's oxygen carrier, holds oxygen more tightly and can bind and release more of it than other forms.
The source saysFoetal haemoglobin has a greater affinity for oxygen, and can bind and release more oxygen than other forms of haemoglobin
The page saysA yak's tongue is 4 cm long on average, shorter than a cow's, and it grazes with its lips.
The source saysYaks have a shorter tongue (4 cm, on average) than cattle, and graze forage using the labia oris
The page saysa yak can lose 25 to 30% of its body weight, or even more.
The source saysyaks can lose 25% to 30%, or even more, of body weight
The page saysGenome studies date the yak's domestication to 7,300 years ago.
The source saysBased on whole-genome resequencing, yaks were domesticated 7,300 years ago
The page saysA 2022 review counted approximately 16 million domestic yaks and 15 to 20 thousand wild yaks in the world.
The source saysthere are approximately 16 million domestic yaks and 15 to 20 thousand wild yaks in the worldNote: the year is the review's (Jing et al. 2022, 'At present'); Ayalew et al. 2021 gives 'Over 17.6 million yaks', citing an older count
The page saysA 2022 review put the domestic herd at about 16 million animals, against 15,000 to 20,000 wild yaks in the world.
The source saysthere are approximately 16 million domestic yaks and 15 to 20 thousand wild yaks in the worldNote: paraphrase of the quote; 15 to 20 thousand = 15,000 to 20,000
The page saysCattle have a reaction in which lung blood vessels clamp down in thin air, which is called hypoxic pulmonary vasoconstriction.
The source saysyaks have a greatly diminished hypoxic pulmonary vasoconstrictive response, which cattle do not have, when exposed to low air oxygen contentNote: the quote implies cattle have the response; term explained in the body's own words
The page saysThat keeps the tongue out of the cold and lets the yak crop low plants.
The source saysgraze forage using the labia oris , which minimizes exposure of the tongue to the cold environment, as well as enabling them to consume low herbages
The page saysYaks are raised 3,000 to 5,000 m up, and a yak's heart weighs 1.18% of its body weight against a cow's 0.39%
The source saysraised at altitudes between 3,000 and 5,000 m above sea levelNote: vibe.reason
The page saysYaks are raised 3,000 to 5,000 m up, and a yak's heart weighs 1.18% of its body weight against a cow's 0.39%
The source saysHeart weight in yaks is 1.18% of body weight as opposed to 0.39% in cattleNote: vibe.reason

Source
02

Ayalew et al. 2021

Ayalew et al. (2021). Adaptation Mechanisms of Yak (Bos grunniens) to High-Altitude Environmental Stress. Animals.

The page saysa shaggy coat
The source saysthe thick fleece covering the entire yak body enhances heat conservationNote: tagline
The page saysYaks have thick outer hair and no working sweat glands
The source saysThey also have thick outer hair coats and no functional sweat glands
The page saysThe fleece has two layers: long outer hair, and an undercoat of dense, fine down that appears in the colder season.
The source saysThe thick fleece comprises an outer coat of long hair and an undercoat consisting of a dense layer of fine down fibers that appear in the colder season to contain body heat and repel moisture
The page saysThe body is compact, with relatively little skin for its weight.
The source saystheir bodies are compact with a relatively reduced skin surface area per unit of body weight (0.016 m 2 /kg)
The page saysnot sweating helps them cope with cold.
The source saysThe absence of sweating in the yak enhances cold tolerance
The page saysA 2021 review describes yak sweat glands as non-functional
The source saysyaks have large hearts and lungs, compact bodies, thick outer hair covering, and nonfunctional sweat glandsNote: 2021 is the publication year of the cited review (Ayalew et al. 2021)
The page saysthe absence of sweating helps yaks tolerate cold.
The source saysThe absence of sweating in the yak enhances cold tolerance
The page saysIn winter, a compact body, thick coat and no sweating together minimize heat loss.
The source saysCompact body, thick outer hair covering, and nonexistence of functional sweat glands Minimize dissipation of body heat during winter

Source
03

Qiu et al. 2012

Qiu et al. (2012). The yak genome and adaptation to life at high altitude. Nature Genetics.

The page saysA 2012 study comparing yak and cattle genomes found that the yak has more genes in families tied to the senses and to energy metabolism.
The source saysGenomic comparisons between yak and cattle identify an expansion in yak of gene families related to sensory perception and energy metabolism, as well as an enrichment of protein domains involved in sensing the extracellular environment and hypoxic stress.

Source
04

Human Ageing Genomic Resources, AnAge

AnAge entry for Bos grunniens. Human Ageing Genomic Resources, AnAge.

The page saysAnAge lists an adult weight of 667 kg for Bos grunniens.
The source saysAdult weight 667,000 gNote: 667,000 g = 667 kg
The page saysA newborn weighs about 18 kg.
The source saysWeight at birth 18,000 gNote: 18,000 g = 18 kg
The page saysThe yak reaches full size in 6 to 8 years.
The source saysThe yak reaches full size in 6-8 years.
The page saysOne captive yak was still living after 26.3 years.
The source saysOne captive specimen was still living after 26.3 years
The page saysGestation lasts about 274 days, a little under nine months.
The source saysGestation 274 daysNote: 'a little under nine months' is arithmetic on 274 days
The page saysAnAge gives a maximum of 26.3 years for a captive yak.
The source saysMaximum longevity 26.3 years (captivity)

How the table was made: a writer drafted the profile from these sources and logged each claim with its quote, a reviewer with nothing but this table checked every sentence said no more than its quote, and a script confirmed each quote appears word for word in the source. The method is in the site'sAbout page.