Adaptation

For over 10,000 years, climate adaptation has driven the evolution of aurochs into cattle into subspecies into breeds. Today, climate adaptation drives breeding programs across the world.

Relative Comparisions

In the cattle industry, "adaptive" is a relative concept. More than just survive, an animal must be able to meet desired performance metrics (e.g. reproduction, weight gain or milk production) given a set of environmental conditions. Different people may have different performance thresholds and perceptions regarding climate. Are we talking Great Plains hot or Gulf Coast hot? Are we talking South Texas cold or North Dakota cold? Are we talking Rocky Mountain elevation or Andes Mountain elevation? Some cattle have adapted to each one of these environments, but the same cattle will likely not survive, much less thrive, in all of the environments.

Heat Cold Altitude

Heat

One subspecies of auroch migrated towards warmer climates, further branching and evolving into subspecies of cattle: Bos taurus indicus in India (commonly known as Zebu) and Bos taurus african in Africa (commonly known as Sanga).

Research indicates that "heat adaptive" traits include:

Coat length - Cattle that are more heat adaptive have no hair or short hair or to a lesser extent, the ability to quickly and readily shed hair. Some cattle have a "slick hair gene", which can cause them to have no hair.
Coat color - Cattle that are more heat adaptive have lighter hair color, which better reflects heat, as opposed to darker hair color, which absorbs heat. Note, cattle can be "dark hided", meaning they can have dark pigmented skin, noses and hooves, while still having light colored coats (hair).
Fat deposition - Cattle that are more heat adaptive tend to deposit fat along their stomach as opposed to along their back. See "thin skinned" below.
Surface area - Cattle that are more heat adaptive tend to be more oblong in their body shape, which gives them more surface area to dissipate heat. They also gain surface area with longer ears and with extra or looser skin.
Skin - Cattle that are more heat adaptive have skin that is "thinner", has more sweat glans, secretes oils and is more vascular. These traits allow them to better reflect or dissipate heat.

Learn more:

How do researchers measure heat tolerance?
Why is heat tolerance such a big deal in the cattle industry?
How has heat tolerance influenced crossbreeding programs?

Cold

Another subspecies of auroch migrated towards colder climates, further branching and evolving into subspecies of cattle: Bos taurus NE Asian in Russian and China and Bos taurus European in Europe and the British Isles (commonly referred to as Taurine).

Cold adaptive physiologically traits include:

Coat length - Cattle that are more cold adaptive have the ability to grow long hair for insolation.
Fat deposition - Cattle that are more cold adaptive tend to deposit fat along their their back.
Surface area - Cattle that are more cold adaptive tend to be more square or blocky their body shape, which helps retain heat.
Skin - Cattle that are more cold adaptive have skin that is "thicker" and tighter along the body. They have smaller ears.

Altitude

Altitude means the height above sea level, and high altitude areas have low amounts of oxygen, atmospheric pressure and temperature. Cattle can climatize to higher elevations by increasing the number and size of red blood cells and breathing more rapidly in order to get enough oxygen. Cattle are more likely to be able to adapt environments that are less than 2,000 meters about sea level. Cattle in mountain areas of 3,000-5000 meters above sea level, are more likely to one or more health and production problems. Cattle altitude sickness result in a number of diseases (hypoxia,pulmonary hypertension, “brisket disease” or "dropsy") and even death.

Some cattle have develop mutations that allow them to better adapt to higher altitudes. A pulmonary artery pressure (PAP) test can be run to detect cattle that are at mot risk for diseases related to altitude as well as in breeding programs to select for more altitude adaptive cattle.

Climate Comparisons

Because the specifications around what is adaptive are so variable, it maybe more useful to talk about adaptation to a specific climate rather than to terms like "heat", "cold" or "altitude". Each region poses a number of challenges for cattle, which can be addressed through trait selection and/or management practices.

Subtropical Tropical Temperate

Subtropical

More than just the heat, subtropical cattle have to handle the humidity and hazards.

Lying between temperate and tropical climates, subtropical climate zones are characterized by high relative temperatures (hot and humid) with relatively low forage quality and periodic droughts as well as harsh conditions related to diseases, insects and noxious plants.

Bar J cattle are located in South Texas. Under the Köppen-Geiger system, South Texas is classified as a humid subtropical climate (Cfa). Humid subtropical climates lie on the lower east side of continents, roughly between latitudes 25° and 35° degrees away from the equator. This includes the SE United States, SE China, SE Australia, SE Brazil, SE Paraguay, Uruguay, and NE Argentina.

Efforts to increase efficiency of beef cattle production in the subtropics have increased over the last century, and a significant percentage of the US calf crop is born in Subtropical regions. This can be seen in the US cattle census. Based on USDA data, 41 million US cows and heifers calved in 2019. Over 1/4th of this calf crop was born in a Humid Subtropical regions, and over 1/3rd of US calves were born in Humid and Transitional Humid Subtropical climates.

Tropical

Temperate

Devil's Advocate

Can a black colored bull be "heat adaptive"?

If you have ever worn a black shirt in the summer time, you know that black absorbs heat. You can also compare the greater number of biting flies on a black cows verse a lighter colored cow to know that black cattle are absorbing more heat. Then why is it common to see people advertise a black colored bull with Bos taurus indicus (e.g. Brahman) influence or that readily sheds hair during the warmer months as "heat adaptive" or "heat tolerant". Because there is not universal definition as to what is an is not "heat adaptive", they maybe marketing the bull in good faith. Cross breeding with cattle adapted Temperate climates with cattle adapted to Tropical climates is going to generate offspring that are relatively more heat tolerant than the Temperate breed. Studies show that if you clip the hair off a steer, it is more heat tolerant than those unclipped. So, cattle that shed are more heat tolerant than those that do not. However, that does not mean that the advertised bull is as heat adaptive as a particular breeding program wants to needs. Then again, maybe he is. What is important is that each breeding program establish specifications around an animal that is "heat adaptive".

Can an animal from a British breed be "heat adaptive"?

Breeds developed in the cold and Temperate climate of Great Britain are generally not as heat adaptive as breeds developed in Tropical and Subtropical climates. That being said, there is great diversity within a breed. Through genetic selection, a rancher can develop animals from a British bloodlines that are relatively more heat tolerant than the average animal from its breed.

Here is a brain twister: Can the most heat tolerant British cattle be more heat adaptive than the least heat adaptive Brahman? Maybe not.

Studies have constantly shown that Zebu and Sanga cattle are more heat adaptive that Taurine cattle, specifically British breeds. The good news is that studies have shown that you can cross breed British cattle with either Zebu or Sanga genetics to produce offspring that are more heat tolerant than their British relatives.

As cattle genomics becomes more cost effective, some have argued that a heat tolerant gene can be introduced into British cattle to make them more heat tolerant. That is essentially what crossbreeding with Zebu and Sanga does. But if we introduce a gene that is not inherently found in British cattle, can we still consider them fully British. Perhaps. Breed associations have become more open to introducing genetics form other breeds.

A bigger question is whether heat tolerance is driven by a single gene or multiple genes. There is a single gene for the slick hair, which has been effectively used in Holsteins to produce more heat tolerant dairy cows. Most likely there are multiple genes that influence heat tolerance, and how many of those genes a breeder needs to meet their program goals will depend on the climate they are in, the performance metrics they want and the traits they value.

Adaptation

Relative Comparisions

Climate Comparisons

Devil's Advocate

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