Livestock Ecology

by Jan Bonsma

Chapter 3 from The Wortham Foundation Lectures in Animal Science

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Animal ecology is the science which explains the interaction between the animal and its total environment. In livestock production it is essential to have a clear concept of how each environmental factor influences the animal and how we can breed animals to be better adapted to any environment. Livestock ecology is explained by the diagram of a wheel (Figure 1). The axle of the wheel is man, the most important single environmental factor in the interaction between heredity and environment. The animal is the hub and is in close symbiosis with man who domesticated the animal. Of 3,000 species of mammals, only 30 different types of animals have been domesticated.

Total environment is presented by the running surface of the wheel, and each environmental factor which acts as a leverage on the animal is a spoke. Each spoke has a direct influence on the animal. To evaluate the interaction between the animal and its total environment, the animal scientist must have a clear concept of what total environment embraces, and it is necessary to indicate how the world is subdivided climatically.

The world is divided into four major climatic zones (Figure 2). The first is KEEN, the regions where the atmospheric temperature never reaches a monthly average temperature of above 65° F and where relative humidity is usually lower than 65 percent. An area which is cold and dry is classified as keen. Cold and dry conditions are antagonistic to promoting plant and animal life, hence, in keen climates we have very little vegetation to nourish animals. Highly productive animals cannot be maintained in a keen climate. In the slightly milder regions of the keen climate, it is possible to keep animals such as reindeer which live on mosses and lichens. In the keen climate we usually find certain fur-bearing animals which live on fish and other nutriments obtained from the ocean or from the sparse vegetation found in those areas.

The next large climatic zone is SCORCHING. In the scorching zone, we have an average monthly temperature varying from 65° to well over 90° F with very low humidity. Scorching areas are semiarid or arid because of the very low rainfall and extremely high temperatures. Plant growth is sparse and the plants, often thorny cacti species, are of low nutritive value.

The next climatic zone is a RAW climate. In the raw climate the average monthly temperature very seldom goes above 65° K, and the humidity fluctuates between 65 and 90 percent. It is the zone best suited for crop and pasture production and an area where climatic stress on the animal is not great. All the improved breeds of livestock have been developed in countries with raw climate. The stimulating and invigorating climatic conditions of those areas might have had a very favorable influence on the efforts of the human inhabitants.

The next climatic zone is MUGGY. Those regions which have high atmospheric temperatures of 65° F. and higher, and where the humidity is 65 percent and higher are called muggy.

To understand the interaction between the animal and the environment better, it is necessary to see various natural environments and to appreciate the climatic conditions which prevail there. Charles Darwin’s writings are a constant source of inspiration and challenge to the biologist, as are his ideas on natural selection and evolution. Ernst Haeckel is another scientist who stimulated my interest in how the ecological relationship between plants and animals plays a tremendous role in their economic success or otherwise. Ernst Haeckel is considered the father of plant and animal ecology.

A region with a typically keen climate is the Arctic Zone. There is very little animal life except for some fish in the fiords which are not iced over; polar bears might get enough food in those areas, In the high Alps of Switzerland above the timber line, the climate also is keen. It is cold and dry, and antagonistic toward animal and plant life; no animals can be maintained at altitudes above the timber line.

The Alpine pastures in Switzerland are in a high altitude raw environment. High altitude raw environments also are found in various parts of Europe, South America, North America and the European Continent where we have altitudes above 4,500 feet. There the rainfall usually is approximately 2 inches per month, and the average annual isotherm does not exceed 60° F. In such areas the pasture growth is very slow, the pastures are very succulent, are low in crude fiber and are high in protein. It is an environment which is very favorable to livestock production. In the high altitude pastoral regions o! Switzerland with its raw climate, grazing often is communal. The pastures are harvested for hay production and the communal cattle owners live in their huts high in the Alps. These herdsmen live there to be near their animals when storms come tip rapidly. These storms are real hazards to the cattle, and human endeavor is essential to prevent heavy stock losses.

Holland is a country with low altitude raw climate. Some of the pastoral areas of Holland actually are below sea level. The average temperature of Holland is below 65° F; it is cold during winter and has an average rainfall of at least 2 inches per month. The rainfall efficiency in Holland is exceedingly high. Pasture values are high because of slow growth, low crude fiber and high protein content, especially where fertilizers have been applied. A large proportion of the pasturage in Holland is on reclaimed land below sea level, and these areas have to be drained. In the past this was done by windmills which are being replaced by centrifugal pumps. The pastures in Holland are divided by shallow ditches, and the animals will not jump the ditches,

Scotland is an example of a raw, low altitude, windy climate where animals need more feed for energy and must have woolly coats to maintain thermal equilibrium.

Another type of environment is the high altitude, semiarid climate of parts of Southwest Africa, at altitudes  of 6000 feet and higher. These semiarid high altitude pastures do not get very cold or very hot. The limiting factor in these areas is the unreliable, fairly low seasonal rainfall and low vegetation density with the accompanying low carrying capacity.

Low altitude, scorching climates are found in most of the semiarid regions of the world such as Africa, Australia and parts of South America.  In the low altitude, scorching climates, the altitude of the ranching areas is usually is less than 2,000 feet above sea level. The average annual isotherm is above 70° F. Rainfall is sparse; it usually varies from approximately 1.2 to 16 inches per annum and often is seasonable and unreliable. The Bushveldt and Middleveldt pastoral regions of the South African savannah country have an altitude of approximately 3,500 feet above sea level. The average annual temperature varies from approximately 63° to 70° F. In these regions the pastures usually are of a natural curing hay type. The soil pH determines whether or not the pastures are high in protein.

In areas with a muggy climate, the problem is high humidity and temperatures.   In such areas the pastures grow rapidly and mature fast, are high in crude fiber and low in protein. Insect, pests, are a serious hazard to the animals in muggy climatic zones. The animal has to overcome the hazard of maintaining its thermal equilibrium, and also has to overcome the hazards associated with ectoparasites such as ticks, mosquitoes and flies. In areas with very high humidity and temperatures such as Fiji, it is almost impossible to maintain Hereford, Shorthorn or Aberdeen Angus livestock or the dairy breeds such as the Holstein and Jersey successfully unless appropriate shelter and nutritional conditions are provided. It is a problem for the animal to maintain a normal body temperature in those areas.

Areas of the southern United States like parts of Louisiana, Florida and Texas have a muggy climate. High temperature and humidity give the soil a low pH; the minerals in the pastures are leached out and in some of those areas the water table is near the surface. Such areas are very deficient in both macro and microelements. In a muggy climate the problem of heat dissipation always is more difficult than it is in a semiarid climate.

In an attempt to understand and appreciate the influence of the climatic regions of the world and their interaction on the animal, it is essential to study animals in their natural habitat. Animal behavior and physiological reactions must be carefully observed, described and interpreted. Adaptability phenomena in animals of particular areas must be assessed to use them in the breeding programs of domestic animals which have to overcome climatic hazards of corresponding environments.

The polar bear is a most beautifully adapted animal to a keen climate; its most obvious adaptability phenomenon is the white coat made up of an inner heat retaining coat and outer protective hair. This forms a formidable insulating coat. In this way radiation of energy from the body surface is reduced and maintaining body temperature is no problem. The polar bear also has a layer of fat approximately 1 inch thick over the body which also insulates. The animal conforms to Bergman’s and Allen’s Laws, that in a cold climate the animal is squarely built, has a small surface area per unit weight and its extremities are relatively short and thick. In the case of the polar bear, its legs are exceedingly thick. If given a diet of fish, this animal will always select those fish which have the highest liver oil content to provide the most readily available abundant source of energy.

The American bison is adapted to the cold Savannah areas of North America.  These animals are beautifully adapted to overcome wind, snow and blizzards. All the vital organs of this animal are protected by a dense outer protective coat and a furry inner heat retaining coat. The bison also has an adaptability phenomenon in its reproductive organs. The testes are carried in a very small scrotum and are drawn into the body cavity during the severe cold weather. Only during springtime when warmer weather appears will the animal drop its testes in the scrotum and become fertile.

The Bactrian camel is well adapted to the cold Siberian desert. It also has an outer protective coat and an inner heat retaining coat. Because of the greatly varying climatic conditions between summer and winter in the Siberian desert, this animal has a thick winter coat which sheds rapidly during spring and the animal becomes practically smooth coated during the summer.

The Rocky Mountain goat has adaptability phenomena, especially for climbing steep ledges and mountains.  It also has a color which makes it adaptable to the environment.

The dromedary camel of the Asian deserts is adapted to the scorching climate of the desert. Its nostrils close when dust storms come up. Its lips and tongue are very poorly supplied with nerve fibers and these animals can consume fibrous and thorny desert plants without injuring the mucous membranes of the lips, tongue and mouth. The animal has false eyelids which cover the eyes when harassed by dust storms. The areas of the body in close contact with the hot desert sand have calloused pads. The camel can drink tremendous amounts of water and by an adaptability mechanism in the digestive system, can maintain itself for several days without drinking water. The feet are especially adapted to desert travel. It has a well protected outer and inner heat-retaining coat during winter which it sheds rapidly during the summer.

Animals adapted to the hot, tropical climates of the African Continent have the adaptability phenomena which conform with Bergmans and Allen’s Law, that the tropically adapted animal has a large surface area per unit weight and the extremities of the animal, its limbs, tail and ears, usually are long, increasing the radiating surfaces of the body.

Animals beautifully adapted to the subtropical environment of the semiarid regions are the kudu and the impala. Both these types of antelope have long limbs, flat bodies and a large surface area per unit weight.

The zebra is really adapted to Savannah country because of mimicry, namely dark and light areas on the body.  They are most difficult to see in forested areas and it is difficult for predators to see and get these animals.

The lion commonly is called “King of Beasts,” but he is completely under the control of man. By reward (feeding) and by punishment with a whip, or “hot-shot” prodder inside, you can control the lion. Man has dominion over the wild as well as domesticated animals and is the most important factor in the environment.

In muggy areas very few breeds of livestock can be maintained. In the muggy climate of Trinidad it is impossible to maintain any improved breeds of domestic cattle, and it will be necessary for man to do a vast amount of selection and breeding work on the water buffalo. The water buffalo is most beautifully adapted to a muggy climate.

Domestic animals exhibit certain adaptability phenomena due to natural selection and selective breeding. In north Scotland, the Scotch Highland breed of cattle is most beautifully adapted to that environment. There the climatic conditions are drastic. It is cold and windy, and moist winds from the North Sea often blow on the cattle. The soil has a low pH, The Scotch Highland breed has an outer protective coat of long medullated hair and an inner heat retaining coat because it is continuously exposed to cold moist winds. As a result of the low pH or low calcium content of the natural pasturage, these animals are very small framed. They are very hardy and can overcome cold, moist wind. Animals of this breed taken to Norfolk in England, an area renowned for its fertile soils and good pastures, became much larger than the animals in their natural habitat. A number of purebred Scotch Highland cattle were taken to Norfolk 200 years ago; they have been selected and bred pure in that environment, and today the Scotch Highland cattle in Norfolk are much larger and heavier than those in Scotland. The difference in weight between bulls in the Highlands and hi Norfolk is approximately 400 pounds in favor of those in Norfolk. The difference between the cows is approximately 200 or more pounds.

The Galloway breed, also originated in Scotland, also is well adapted to a windy, cold climate. Animals exposed to cold, windy climates usually have a long outer protective coat and an inner heat-retaining coat and are square in body conformation.

The black-faced Scotch Mountain sheep are well adapted to the tremendously hard climates found in north Scotland. Interestingly, these sheep have a very short breeding season. Those lambs born out of the 6-weeks lambing season will succumb. The ewes come in heat for a short period and are anoestrus the rest of the year.

The Bos Indicus species of cattle such as the Afrikaner of Southern Africa and the Brahman of the Americas and Asia are well adapted to the subtropics and semiarid regions. The Afrikaner shows some very interesting adaptability phenomena: They are sleek coated, have a, large surface area per unit weight, fairly well developed dewlap and sheath or naval fold. They have well developed panniculus muscles and usually are thick hided. Downward skin folds in the hide indicate a thick hide. Animals with a thick, pliable or movable hide have a high vascularity of hide; that is, the blood flow to the hide is profuse and such animals are well adapted to high temperatures- and usually have tick and fly repellent hides.

The most important spoke in the wheel is nutrition. Natural vegetation depends on rainfall, temperature and humidity. Types of animals maintained in any area depend on the total nutritional level of that environment.

In 1953, an advertisement by a company which produces animal feeds intrigued me. They indicated that, in 1910, 500 pounds of their pig rations were required to cause a 100 pound gain in weight, and the pigs reached 100 pounds in 5 months. By 1930, improved rations could cause the pig to gain 100 pounds on 364 pounds of feed. In 1953, the pigs could gain 100 pounds on 300 pounds of feed and they could top the 200 pound mark in 5 months. These people concluded that the great improvement made in balancing their rations by adding antibiotics, minerals, vitamins and balancing the amino acids in the proper portions could produce rations that could make pigs gain 100 pounds on 300 pounds of feed. This advertisement is a half-truth. From 1910 to 1953, livestock breeders changed the body conformation and function of these animals and the improved rations were only partly responsible for the increased and more efficient weight gains.

As a result of this advertisement, I bought unimproved native pigs in the Bantu territories of South Africa and brought them to the University of Pretoria. There we maintained a number of Bantu sows and a number of Swedish Landrace sows. Young pigs of the unimproved Bantu type and highly improved Swedish Landrace pigs were divided into two groups, one group was put on a 1913 unimproved ration composed of com meal and a little tankage, and the other group was placed on a very well balanced 1957 commercial ration. The most amazing results were obtained. The Bantu pigs fed on the 1957 commercial balanced ration suffered badly. They grew slowly, scoured regularly and made very poor gains. The Bantu pigs on the 1913 ration flourished and weighed 135 pounds when those on the 1957 ration only weighed 85 pounds. This was a difference of 50 pounds in 8 months.

Improved Swedish Landrace pigs on the 1857 ration weighed over 200 pounds at 6 months, while those on the 1913 ration weighed only 180 pounds. There is no doubt that the two types of pigs differed markedly in their ability to use various types of rations. Sows of the Bantu and Swedish Landrace breeds were mated to Bantu and Swedish Landrace boars. Both breeds of sows gave birth to purebred and crossbred litters. Hence, we succeeded in producing purebred and crossbred litters which had the same prenatal environment. The crossbred pigs on the good rations did well, while the Bantu pigs on the good rations made very poor growth. The Bantu, pigs on the 1913 rations produced a tremendous layer of fat which had a low iodine value, that is a firm fat, contrary to all expectations. The Swedish Landrace pigs on the 1913 ration produced an oily fat. The .1957 ration, which gave a firm fat in the Swedish Landrace pigs, gave an oily fat with high iodine value in the Bantu pigs. The crossbred pigs produced by the Bantu sow and the Swedish Landrace boar weighed 200 pounds on the 1957 ration, while their littermates which were pure Bantu pigs only weighed 100 pounds.

At Robe Research Station in Australia the pastures are poor in copper and cobalt, and sheep suffer severely from cobalt deficiency. They get sway backs and steely wool and many sheep breeders went out of business because of the copper and cobalt deficiency. The classic work done by Marsden enabled those breeders to overcome the problem of the trace mineral deficiencies of copper and cobalt by adding small amounts of copper and cobalt to the rations or by squirting a little copper sulfate solution in the mouths of the sheep. Black sheep which suffer a copper deficiency develop a white line in the black wool when they are on a copper-deficient ration. When copper is added to the ration, these animals produce black wool again.

It is essential in evaluating the nutritional and mineral deficiencies of an area that the cattleman should know the indigenous trees of an environment. Those areas in which Tarconanthus camphoratus, a shrub indigenous to South Africa, grows naturally are usually deficient in phosphorus. In all phosphorus-deficient areas, cattle breeders suffer severe financial losses if they do not feed phosphate supplements. Phosphorus deficiency causes much lower fertility and much slower growth rate. Steers which received 2 1/2 ounces of bone meal under phosphorus-deficient conditions had carcasses weighing approximately 750 pounds at the age of 4 years, while the control steers which did not receive the ounces of bone meal daily had carcasses weighing 350 pounds.

The rainfall and temperature of any particular region determines the protein value and the crude, fiber content of pastures. In all regions of Britain where domestic breeds of livestock, such as the Hereford, Shorthorn, Sussex and Aberdeen Angus have been evolved, the average monthly rainfall is approximately 2 inches per month and the atmospheric temperature varies from, an average monthly temperature of approximately 40° F. during the winter to approximately 80° to 65° F during the hottest summer month. In those areas with a temperate climate and a steady rainfall, pasture growth is slow, crude fiber is low and crude protein is high. Those are the areas having very succulent pastures.

New Zealand, has an average monthly rainfall of approximately 2 ½ to 3 inches per month and an average monthly temperature seldom exceeding 85° F. In that country probably are found some of the lushest, mainly artificial pastures in the world with a high carrying capacity.

In most semiarid countries the rainfall is seasonal; there are dry seasons with no rain or practically no rain and short seasons with very heavy downpours. In. South Africa, the average rainfall in some of the semiarid regions is approximately 16 inches; approximately half falls from the beginning of December to the latter part of February. The average monthly temperature varies from approximately 60° to 80° with an average annual isotherm of 65° to 76° F. In those areas pastures grow very rapidly; hence are very high in lignin content, that is the crude fiber content is very high and the protein value is low. In semiarid regions, livestock often suffer from nutritional deficiencies of energy and protein for a fairly long period during the year.

Temperature is most important in determining which type of animal can be maintained in a particular region. In areas where the atmospheric temperature is high and where the average annual isotherm (the average temperature for the year) is high, unadapted cattle will degenerate. Few British breeds of livestock can thrive in areas where the average annual isotherm is above 65° F. If it exceeds 700 all British breeds of livestock will suffer from tropical degeneration. Tropical degeneration is not only characterized by stunted growth but also by a marked reduction in fertility. Animals not tropically adapted, which cannot withstand high temperatures, become hyperthermic and often show a rise in body temperature as high as 104° to 106° F. Young animals from birth to 1 year suffer appreciably more than older animals. The young animal’s thermo-regulation mechanism is not functioning properly and only after the animal is approximately 1 year old can the unadapted animal maintain a body temperature a few degrees lower than what they would have had if they were younger. The tropically adapted animal will show little if any rise in body temperature at atmospheric temperatures of 85° F. and higher. Animals which show symptoms of hyperthermy are tremendously retarded in growth and Shorthorn, Hereford and Aberdeen Angus cattle at the Messina Research Station in Northern Transvaal often weighed as little as 700 pounds at 3 years of age, while the adapted animals that are heat tolerant weighed 1,100 pounds or more.

The tropically adapted animal is smooth coated and has a thick movable hide of high vascularity. Animals of the British breeds, although they are often born beautiful, have an outer protective coat and an inner heat-retaining coat. Animals not born with a sleek or smooth coat will suffer severely when young. A calf which is born beautiful may weigh as little as 280 pounds at 8 months weaning. These animals have heavy coats, and as a result of hyperthermy on hot days may suffer pituitary damage. Such animals are very retarded in shedding their hair; often it is delayed until the age of 3 to 4 years. These animals are usually sterile; they have very small pituitaries — 1.4 to 2.5 grams. Postmortem examination shows they have infantile ovaries in most instances.

Some of these tropical degenerates have the typical body conformation of the sterile animal. In one instance a typical tropically degenerated cow was removed from the Messina Research Station (average annual isotherm 70° F) to the Experimental farm, Pretoria University with an average isotherm of 68° F. At the age of 11 years she had had no calves at the Messina Research Station, but when removed to the Pretoria University Research Station this cow gave birth to her first calf at the age of almost 12 years. Although sub-fertile, the change to a temperate environment and a better nutritional level caused her to ovulate and to get in calf. 

Hair and hide play a tremendous role in the adaptability of animals. A mutant woolly coated purebred Afrikaner bull, whose sire was a show-winning bull and whose mother was an outstanding Afrikaner cow, was obtained for tropical research work. This woolly coated bull was brought to the Messina Research Station and mated to sleek coated Afrikaner cows. Approximately half of his progeny were woolly coated and half sleek coated. In every instance, the sleek-coated cattle outweighed the woolly coated ones. The woolly coated progeny became tropically degenerated. The woolly coats acted as an insulating layer which did not facilitate the radiation of energy from the body. The smooth-coated heifer calves by this bull weighed an average of 400 pounds at 8 months and the woolly coated heifers, 300 pounds. The. woolly coated Afrikaner bull was mated to Aberdeen Angus, Shorthorn, and Hereford cows. One Aberdeen Angus cow-produced two bull calves by the woolly Afrikaner bull. The first bull calf was woolly coated and the second bull calf was smooth coated. At the age of 7 years, the woolly coated steer weighed 870 pounds and the sleek coated steer weighed 1,360 pounds. It is obvious that hybrid vigor had no value whatsoever in the animal that was not adapted.

Several of the woolly coated Afrikaner bull’s purebred female progeny were mated to sleek coated Shorthorn bulls. The Afrikaner cows which were the progeny of the woolly coated Afrikaner bull by sleek coated Afrikaner cows produced some smooth and some woolly coated calves. When the Afrikaner- cows which were heterozygous in coat cover were bred to smooth coated Shorthorn bulls, they produced smooth and woolly coated calves. The calves that were bora sleek coated could overcome the hazards of the subtropics; they did not show a rise in body temperature or hyperthermy not even when they were young. Those born woolly coated could not overcome the hazards of high temperatures. At the age of 8 years the steers born sleek coated weighed an average of 1,080 pounds, while those born woolly coated weighed only 800 pounds.

The animal with a sleek, thick hide with high vascularity will bleed profusely if the hide is punctured but injuries will heal rapidly. Such animals are well adapted to high atmospheric temperatures. Wounds inflicted in the animal with a thick, movable, vascular hide heal within a week to 10 days. Wounds in the animal with a woolly, thin coat with low vascularity often take 3 weeks or longer to heal.

Miniature calves could be produced when low heat-tolerant cows were mated in early spring and were pregnant throughout summer. Calves as small as 19 to 40 pounds were produced from low heat-tolerant cows pregnant during the summer. In every instance the bull calf weighed lighter than the heifer calf. These results because the male fetus has a higher metabolic rate than the female fetus, and the cow which suffers from hyperthermy suffers appreciably more when pregnant with a male calf. In normal calves, the male always is heavier than the female. These calves often are so small that they can barely reach the udder of the cow. Miniature calves are often caused by the lack of adaptability of the mother. Heat tolerant Afrikaner cows mated to Hereford bulls produced heavy calves at birth while Hereford cows with a low heat tolerance mated to Afrikaner bulls produced miniature calves. The difference in weight between the two reciprocal crosses was approximately 75 pounds as compared to 40 pounds. 

In Australia, small miniature lambs in areas such as Queensland were found, and none knew what caused miniature lamb production. In 1949, when the results on the cattle were discussed in Australia it was mentioned that the miniature lambs might be caused by ewes pregnant during midsummer. Perhaps some ewes were more heat tolerant than others and those ewes which lack heat tolerance would produce small lambs. Drs. George Moule and Neal Yeates mated a number of ewes and placed half the pregnant ewes in cold rooms and half in hot rooms. Those placed in an environment of 85° F produced lambs weighing 4 pounds. Those placed in an environment with an average temperature of 65° F produced lambs weighing on an average 8 pounds.

Light is an important environmental factor greatly influencing the metabolism and behavior of animals. Light is the most constant of the natural phenomena. Temperature on a specific date in different years might vary markedly, but the daylight length on one date of one year is the same as that of another year. Light has a marked influence on the metabolic process, sexual activity and on hair shedding of the animal.

Light colored or white animals become photosensitive when they eat certain types of plants. If a cow eats goathead (Tribulus terrestris), the white area of such an animal’s body will slough off and become one festering sore.

When other animals such as horses and mules eat plants which make them photosensitive, such as goathead, they will develop many photosensitivity symptoms. A white mule consumed  Tribulus terrestris and his hide looked as if it were corrugated. The unpigmented areas were swollen while the pigmented areas were normal. Animals which consume plants like lantana suffer severe photosensitivity. if a cow or horse eats lantana, it becomes photosensitive and will die if exposed to light. A Friesland cow which consumed lantana exhibited severe photosensitivity symptoms, all the white areas of her body were badly inflamed; it became one large sore and lost all white hair. The animal was placed in a dark stable and recovered. All mucous membranes were also severely inflamed. Horses which consume plants which make them photosensitive develop vast sores on their bodies called sand bum in Texas. As early as 1909, the veterinarians of the Department of Agriculture in the United States tried to solve this problem and as yet have not found an answer. It is advisable to put animals which suffer so severely from sandburn in a dark stable.

Radiation also has a marked influence on the animal. Animals which have no pigment in their eye suffer severely. The most important rays which impinge on animals and cause damage are ultraviolet. Daylight is composed of a spectrum of colored rays: red, orange, yellow, green, blue, indigo and violet. The rays just beyond the red spectrum are infrared rays, and they are heat rays. Beyond the violet spectrum are ultraviolet: rays. These rays are chemical rays and when they impinge on an animal that has no color in the hide or has a dry hide from a lack of sebum secretion, these animals will suffer severely. The white animal will develop cancer or hyperkeratosis of the hide where the hide hardens and becomes very sensitive. White faced animals like the Hereford will develop cancer on the eyelid from moisture forming on the eyelid due to dust, or other matter which irritates the eye. Constant radiation of ultraviolet light may cause cancer on the eyelid or on the eye itself. The white-faced animal which lacks pigment in the sclera of the eye develops a cancer in the eye. Many ranchers have these cancers removed by surgical operation, but this is not very successful. We can, by selective breeding, breed Herefords with pigment around the eyes. The incidence of cancer in eyes of animals which have pigmented eyelids is negligible. By strict selection for pigment around the eye, the amount of pigmentation can be increased and such eyes will never suffer from eye cancer. A survey on Hereford cattle in South Africa showed that in young animals, the proportion of animals with pigment around the eye is relatively low. In the older age group, of 6 years and older, the proportion of animals with pigment around the eyes was much greater. Therefore, the mortality rate of the animals without figment around the eye is appreciably higher up to the age of 6 years than it is in those that have pigment around the eyes.

Animals can overcome the hazards of ultraviolet radiation if they have pigmented hides. A white color in the animal is a hazard especially if the hide has no pigment in it. Animals which are tropically adapted like some of the Brahman breeds, white Afrikaner or white ‘N duni cattle, will have pigment in the hide. If the hair is shaved off, the hide will appear to be brown or black. These animals with dark hides can overcome the hazards of ultraviolet radiation and usually they have a profuse secretion of sebum in the hide which is spread over the hair and the sebum acts as an ultraviolet filter. Animals without pigment suffer severely and all breeds of livestock which lack pigment in the hide suffer from a condition called “white heifer disease.”

In a group of ‘N Guni cattle, those with pigment in the hide show a dark number when branded, while those devoid of pigment in the hide show a white number. Those animals which are white suffer severely from ultraviolet impingement and usually are sterile.

The influence of coat color and cover on the adaptability of animals is not well understood.   It is essential in future research that more work be done on determining how color influences the adaptability of the animal to higher incidence of infrared radiation, ultraviolet radiation and total solar radiation. It is essential to determine how these various colors react under the different nutritional conditions. At the Messina Research Station in the Northern Transvaal of South Africa, I bred cattle which were black, red, ash grey or agouti, golden yellow and white. I intend to put these animals under artificial ultraviolet radiation, infrared radiation, test them in the photo-period room and under natural conditions to determine how these animals react.

High altitude is a problem to most animals. In high altitudes, cattle must have a higher hemoglobin index than at low altitudes. In the early work done by Duerst, a Swiss animal scientist, it was proved that the high altitude cattle of Switzerland, the Brown Swiss and the Simmental had a higher hemoglobin index than any of the other breeds of cattle in Europe. We must evaluate the adaptability phenomena of animals adapted to high altitudes to understand the adaptability phenomena required by cattle at those altitudes. The llama, an animal well adapted to the high altitudes of the Andes Mountains, has a red blood count of more than twice that of the human being. The llama on average has 14 million red blood cells per cubic centimeter; man has approximately 5 million. The affinity of llama blood to oxygen also is twice as high as that of the human being; hence the llama is four times as efficient in utilizing the oxygen in the rarefied air at high altitudes as is man. At high altitudes, we find various breeds of cattle which show certain adaptability phenomena. In Switzerland are found the Simmental and the Brown Swiss, and from a color point of view, the Brown Swiss with its dark pigmented hide is appreciably better adapted to the high altitudes than the Simmental. The Simmental white areas become hyperkeratinized and the animals often suffer. In high altitude, semiarid regions like southwest Africa, the white areas of the Simmental are a real hazard.

Animals at high altitudes such as those existing in parts of Switzerland and southwest Africa must have pigmented hides. Because of high altitude, the ultraviolet impingement is very intense. The oxygen content of the air is low, and an animal like the Brown Swiss is beautifully adapted to those high-altitude environments. It has a dark hide containing brown pigment which assists the animal in absorbing infrared radiation during cold weather. It can overcome the hazard of ultraviolet radiation. It is a fairly slow grower, can overcome the hazard of irregular nutrition levels and has a high red blood count. For these reasons Brown Swiss can easily be adapted to a subtropical environment.   The subtropics also have a high ultraviolet radiation impingement. It has low oxygen tension from high temperatures. The only problem the Brown Swiss has to overcome in the tropics is to radiate energy, and that can be brought about by selecting sleek coated Brown Swiss.

Another environmental factor which requires certain adaptability phenomena in the animal is wind. In the northern parts of Scotland and the eastern seaboard of New Zealand, cold and moist wind blows continuously. The most beautiful adaptability phenomenon in animals adapted to cold moist winds is their two types of hair, the inner heat retaining coat and outer protective coat, and these coats are charged electrically opposite. The inner heat retaining coat is positively charged and the outer protective coat is negatively charged. If wind blows over these animals, the charge, becomes stronger and the hair packs closer and the animal becomes waterproof and coldproof and the insulating coat is functioning efficiently.

Pigs constantly exposed to severe cold and wind develop long, woolly hair. In the forests of Yugoslavia, Mangalitsa pigs exist on nuts and are exposed at all times to the climate; these pigs are woolly coated, almost as woolly as a sheep. In 1770, Captain Cook on his exploratory travels in the Antarctic dropped a number of pigs of the type maintained in England at that time, on the Campbell and Cook Islands in the Arctic Zone south of New Zealand. In 1943, a few research workers of the Ruakura Research Station in New Zealand stationed on the islands to do radar work during World War II encountered long haired pigs having an inner heat retaining coat and an outer protective coat. Only those pigs which had the genetic potential to develop an outer protective coat and an inner heat retaining coat could survive. After almost 200 years, there were large numbers of pigs well adapted to the Arctic regions.

An environmental factor which has received very little attention in the literature on ecology is soil pH. Where the soil pH is high, nitrification of bacteria in the roots of leguminous plants can take place, and if nitrogen can become available to pastures, the pastures are higher in protein value. Leguminous trees like some of the Acacia species are indicative of a high soil pH.  A soil pH of approximately 6.5 will produce pastures relatively high in protein. The calcium in such pastures usually is readily available to the cattle and they have good skeletal development.

The type of plant growth may be indicative of the pH of the soil and the skeletal development of animals. At the Mara Research Station pasture having a high pH, where the predominant tree is Tribules terestis we grew large cattle.  In a pasture not 8 miles away we had Combretum apiculatum grazing where there was a low soil pH, and animals kept in these pastures were appreciably smaller.

Steers indicative of the average of two groups kept in the Tribules terestis pastures, and steers in Combretum pastures differed 300 pounds in weight at 3½ years. The steers in the Acacia pastures averaged 1,250 pounds when those in the Combretum pastures weighed only 950 pounds. So many Texas cattlemen do not appreciate why cattle from East Texas grow bigger if moved to West Texas. Most pastures in East Texas grow in areas with a low soil pH and adding lime would add tremendously to the nutritional value of these pastures.

The Afrikaner breed, indigenous to the semiarid subtropical areas of southern Africa, are beautifully adapted to the Savannah country where Acacia trees predominate and mature cows weigh approximately 1,200 pounds.

The ‘N Guni cattle are best suited to the low pH pastures of the coastal regions and to the higher rainfall, lower pH areas of Swaziland. The mature cows weigh approximately 750 pounds. Afrikaner cows maintained on pastures with a soil pH of approximately 6.2, averaged 300 pounds more than Afrikaner cows maintained on pastures with a soil pH of 5.4. The problem of varying soil pH values had a marked influence on the skeletal development of cattle in Holland. This was known 100 years ago. It was known in Holland that cattle maintained in areas where forests and sandy soil with low pH existed had small body conformation and were light boned. Animals kept where soil had a high pH were large framed and heavy.

Animals adapted to low soil pH and high humidity are most often shade lovers. The ‘N Guni cattle in Swaziland, where the humidity is high and the soil pH is low, are shade lovers because of the hazard to the animal to radiate energy in a humid climate when not in the shade. Hence, these animals are forest dwellers. Animals in coastal and humid areas often are very light colored, ash grey or almost, white and must have pigmented hides.

A hazard to many animals in their natural environment is insects, ticks, mosquitoes and flies. Tick-borne diseases are a serious hazard to most areas of Africa, and in research work done by Baque in Cuba many years ago it was found that ticks remove as much as 96 kilograms of blood from one animal per annum. We can overcome this hazard of ticks by proper management and breeding. Animals can be bred to be tick repellent. Those animals which have thick movable hides, well developed panniculus muscles and a sensitive pilomotor nervous system will move their hides very rapidly upon the slightest irritation and will be much more tick repellent than those animals with woolly hair and thin hides. The tick-repellent animal has well developed panniculus muscles; those not tick repellent have poor panniculus muscle development. The hide of the animal where tick borne diseases are a hazard is one of the most beautiful immunizing organs. Those animals with thick hides become immune much more readily and succumb much less to tick-borne diseases than those with thin hides and woolly hair.

Conquering the screwworm hazard in Texas and in the southern United States will completely change our approach to livestock production. By eradicating the screwworm fly, the screwworm problem has almost become a thing of the past, and the increase in the deer population in many of our natural grazing areas has caused us to realize that the livestock carrying capacity of these pastures has changed. Since the screwworm is eradicated, we can now probably produce calves in other seasons of the year than we did in the past. I believe that by conquering this plague the livestock industry will have to do new research on cattle pasture management, breeding seasons of cattle and carrying capacity.

Animals vary in their ability to overcome flies and other insects. Certain cows or horses are full of flies and other biting insects, while others are free from them. It is possible to breed tick-repellent, fly-repellent and mosquito-repellent cattle. The animal with straight hair, sensitive pilomotor nervous system, well developed panniculus muscles, and which gives off sebum, is much more insect repellent than the animal which has a dull, dry coat which does not have a sensitive pilomotor nervous control. The animal whose hair stands upright when it looks like it is going to rain, is a tick-repellent and fly-repellent animal. The erector pili muscles make the hair stand up, and this in all probability stimulates the secretion of sebum in the hair.

Internal parasites often become a hazard to animals. Where rainfall is periodic and intense in the summer, animals often drink stagnant water in muddy tanks and suffer from internal parasites such as liver fluke and various types of worms. Animals on artificial pastures with a very high stocking rate often are infested with internal parasites. Animals on artificially irrigated pastures are more parasite infested in pastures irrigated by overhead spraying, than those flood irrigated. The problem of maintaining large numbers of cattle on intensive artificial pastures is largely one of internal parasites. Animals susceptible to external parasites also are more susceptible to internal parasites. The less adapted animal with a lower nutritional status in a particular environment usually has a high incidence of external parasites and is often infested with internal parasites of one kind or another.

Disease plays a tremendous role in livestock production, and lack of adaptability causes animals to be more susceptible to various diseases. With diseases such as rickettsiosis (heartwater), a tìck-borne disease, certain breeds of cattle are much more susceptible than others, and animals with low heat tolerance usually succumb more readily than do well adapted heat-tolerant cattle. Sheep which suffer from this disease, if they survive, lose their fleece.

In some parts of the world, nutritional conditions cause certain endemic disease conditions. Subterranean clover in Australia, high in estrogenic hormones, causes bearing down disease in sheep, which is prolapse of the uterus. Any disease which causes the animal to have a high temperature for a few days will result in permanent damage to the pituitary, and such animals will never shed their hair or grow out normally. They always are subfertile.

The most sensitive index of adaptability in all animals is their ability to reproduce and reproduce regularly. Endocrine balance is the most sensitive barometer of the animal’s ability to adapt to a particular climate. The scrotum of animals is a thermo-regulatory mechanism, and in some breeds of goats the testicles are carried in two separate scrotums so thermo-regulation is more efficient. The testes are in a scrotum with an appreciably larger surface area than would have been the case if the testicles were in one scrotum. The scrotum of adaptable cattle has a much thicker hide than those of cattle not adapted to the subtropics. Those breeds adapted to the tropics have scrotums which pucker on cold days. Furthermore, the spermatic vein in the subtropical and tropically adapted breeds is much more tortuous than in cattle from the temperate zones. When injected with radio opaque substances such as Chlor-bismuth the volume of radio opaque substance that can be injected into the spermatic vein of the Bos Indicus breeds is much larger than that which can be injected in the spermatic vein of the Bos taurus breeds. The ability to maintain a testicular temperature a few degrees lower than the body temperature is most important for normal spermatogenesis to take place. Injury to the scrotum often causes a varicocele and the thermo-regulatory mechanism is upset. In bulls where a varicocele has developed, the testes become lower and lower hanging and are even more prone to injury than those of a normal bull.

In livestock ecology, man is the most important single factor in the environment and is necessary to breed livestock better adapted to certain climatic regions. The interaction between man and his cattle must be closely studied.

In a country like Switzerland where the symbiosis between man and his cattle is close the availability of labor is poor,  every individual in the cattle farming community has to contribute toward producing fodder for the cattle, and every individual in the family assists in haymaking. The relationship between the animal, man and the environment is very obvious in Switzerland. Every cow carries a bell around the neck because storms come up very rapidly and are hazardous to the animal. Cattlemen who live in huts on the communal grazing must bring cattle to safety during storms and these animals can be reached rapidly by persons knowing the sound of each bell. Those huge bells on the animal’s neck are really a part of the ecological setup between man and his animals. He has to know the bell; it directs him to his cattle at times of urgency, and he can bring them to safety if hazardous storms come up swiftly. In summer the are kept in stables because the hot humid environment in midsummer is conducive to a high incidence of flies and other insects. Animals kept in stables are fed during the day, and every animal’s tail is tied to the roof to prevent it from hanging in the urine gutters.

There probably is no country in the world where the symbiosis between man and his animals is closer than in Holland. The stable and the homestead in Holland are often under one roof. In winter the animals are the air-conditioning mechanism of the Dutch homestead; the heat given off by the stabled animals keeps the house warm. The stable and the living room are separated by a single door. Above the animals in the stable is the barn containing hay. The animals are under continuous supervision by the owner and many of these cattlemen say their cattle have a soothing and calming effect upon them. The tranquility of the cows chewing their cuds in a comfortably warm stable has a favorable psychological effect on the husbandman; if they are worried the first thing they do is to go into the stable with the tranquil cattle.

During winter the Friesland cattle are kept under an artificial climate created by the radiating energy in the stables. When these animals are out on the pastures in Holland, portable milking machines are taken to the cattle which are milked on the pastures.

In France, where they have Charolais cattle, the main object of these animals is to produce beef with very little fat. Hence, they have produced large cattle which can only be produced on pastures with high nutritional value. The pastures in the regions of Nievre and Vichy, France where the largest herds of Charolais cattle are found are very lush and have many herds in them. The animals during summer show a dark discoloration around the pin bones from scouring on lush pastures. The Charolais cattle are lethargic and will not move even if a person goes up to them. They also have little resistance against tropical and subtropical diseases when taken from their natural habitat. The white color of these animals in some instances is a serious hazard.

In a country like New Zealand where no concentrate feeding takes place and ail the production of milk is off green pastures, cattlemen select those Jersey cattle with tremendous stomach capacity to enable them to produce enough milk. Only those animals which consume enough green pasture to produce enough energy and nutriment on, die total digestible nutrient and dry matter basis are maintained in the herds. Ninety percent of the dairy cattle in New Zealand are Jerseys with tremendous stomach capacity. New Zealand has lush pastures and no concentrates are fed to cows there. Most cows calve in early spring and the incidence of twinning in New Zealand is appreciably higher than other parts of the world. At the Ruakura Research Station in New Zealand there were 222 pairs of identical twins in. experimental work.

The standard of livestock production in a country depends largely on the cultural and religious background of the people. In Africa, India and other parts of the world where the people are ignorant, superstitious and prejudiced, the cattle are poor. In Ovamboland, the cattle are kept overnight in corrals and the cows are milked by women in pails cut out of wood that are never washed.

Animals in a natural habitat will exhibit certain adaptability phenomena. In thickly forested areas, we want black cattle because black cattle function better in an environment where the light is dull, where the incidence of infrared radiation is low, and where the ultraviolet radiation is fairly high. In areas of dense forest like parts of Mozambique, Swaziland or Angola, we find predominantly black cattle. Beyond the forested areas in the open Savannah country, the color of the animals changes to a grey, light fawn or yellowish white color.

In open Savannah country where the infrared radiation is intense and where the problem of high temperature is more pronounced than in areas of a more temperate climate, preference would be given to red or light-colored cattle with pigmented hides.

A thorough knowledge of livestock ecology is essential if we want to select and breed tropically adapted cattle. In cattle of the British beef breeds enough variation in the coat cover is observed to enable us to select the variants which exhibit adaptability phenomena. If sleek coated, thick hided animals are selected, they will be much more heat tolerant than those which are woolly coated. The undesirable woolly coated calves can be recognized at a very early age, as early as 3 days, by a felting test on their hair.   A small sample of hair is taken from the animal’s coat with a pair of small scissors, spit upon and rubbed intensely. If the small sample of hair felts into a tight, mass, the animal will never become sleek coated in a subtropical environment. A sample of hair of those animals with smooth, straight hair which is medullated will not felt when moistened and rubbed. The hair of the woolly coated animal is of two types, an inner heat retaining coat, not medullated, and an outer protective, coat which has medullated hair. There are primary and secondary hair follicles in the hide. The smooth coated animal has medullated hair only. A hair comes out of each primary hair follicle, and in most instances,  there is a sebaceous gland attached to each hair follicle. Hence the secretion of sebum in the smooth coated animal is appreciably higher than in the woolly coated animal.

The complete coat cover of animals of the British breeds have been closely clipped and pet through a felting machine. The hair of the woolly coated animals felted into a tight mass required a pull of 26 pounds to pull it apart. In the sleek coated animals, a pull of 4 pounds will separate any sample of semi-felted hair. Animals with hair without felting properties are the tropically adapted.

In Herefords, further selection should take place to get them pigmented around the eyes. Although we can without great difficulty get the animals of the British breeds heat tolerant, it is very often much more difficult to get them immune to endemic diseases of the subtropics. In our research it was possible to change the mortality rate of the British breeds from approximately 30 percent to 10 percent by breeding them to be tropically adapted. One reason why calves resulting from a cross of Brahman bulls and Hereford cows are not as good as the animals produced by the Hereford bulls and Brahman cows is that Brahman cows possess much greater natural immunity against the endemic diseases of the subtropics and tropics. The calves suckling Brahman mothers in all probability obtain a greater spectrum of immune bodies through the colostrum of the highly immune cow. Where we switched calves from the Hereford mothers to Brahman mothers and vice versa, the mortality rate of those calves which suckled the Brahman cows was lower than that of those that suckled the Hereford cows. It is a field of research which should be carried out on a large scale in the southern United States.

Out of a tropically degenerate Hereford herd, it was possible to breed by strict selection for adaptability a herd of Hereford, very well adapted to the subtropics. Selection was based on sleek coats, thick hides and pigmentation around the eyes. At the Mara Research Station in Northern Transvaal, a Hereford herd bred for tropical adaptation was established. In a period of approximately 15 years, it was possible to breed a completely adapted Hereford herd with all the adaptability phenomena required for tropical adaptation. The only factor which could not be overcome was the susceptibility of these animals to tick-borne diseases, although, the incidence was reduced. The Hereford bulls selected in this program were all thick hided as indicated by downward skinfolds; they had pigment around the eyes, and the color of the hair on. the neck, upper flank, lower rib regions and lower thighs was appreciably darker than the other hair.

A survey made on the Hereford cattle in three ecological regions of South Africa found that Hereford cattle with sleek hair in the subtropics were 200 pounds heavier at maturity than those that were woolly coated. In the region of the Mara Research Station the average mature weight of woolly coated Hereford cows was 990 pounds. Medium coated animals weighed 1,090 pounds, while those that were sleek coated weighed 1,187 pounds. In a temperate region the difference was l,030 pounds for woolly coated cattle, 1,044 for medium coated cattle and 1,071 for sleek coated ones, a difference of only 41 pounds between the sleek coated and woolly coated cattle in the temperate region. It became very clear from this survey that adaptability phenomena such as a smooth hair coat is of much greater importance in a subtropical region than in a temperate region.

All animals can overcome cold if they are well fed. The major livestock problem in all tropical and subtropical regions where the average annual isotherm is above 65 degrees is tropical degeneration. When the adaptability work at the Mara and Messina Research Stations was started in 1937, those areas had thousands of cattle of the British breeds — Shorthorn, Hereford, Angus and Sussex — which were typical tropical degenerates. After careful research on the factors which bring about adaptability, in the subtropics, it was possible by selection, breeding and crossbreeding to replace these animals by adaptable types. At Mara Research Station by crossbreeding and inbreeding, a new breed of cattle has been evolved, the Bonsmara. The Bonsmara was bred on fairly similar lines as that adopted in the breeding of the Santa Gertrudis in the United States, but we adapted a few different methods in our selection program. Very little was left to empirical standards; animals were tested for climatic adaptation by taking their body temperatures, respiration rates and pulse rates. It was decided to breed cattle 5/8 Afrikaner, 3/16 Hereford and 3/16 Shorthorn. After obtaining 5/8 Afrikaner-3/8 Hereford cattle, and 5/8 Afrikaner–3/8 Shorthorn cattle, these two types were interbred to get the 3/8 Afrikaner, 3/16 Hereford and 3/16 Shorthorn. It was found that animals with more than half the blood of the British breed could not withstand the subtropical conditions.

Hereford were brought in because they are better grazers than the Shorthorn, more heat tolerant and have a more even fat distribution than the Shorthorn. The Shorthorns were brought in because they are faster maturing than the Hereford, have better milk production and are a uniform red color. By crossing the 5/8 Afrikaner 3/8 Shorthorn with the 5/8 Afrikaner 3/8 Hereford it was possible to develop a red animal with no white on it. I am opposed to white on any animal.  I consider it a hazard to any animal in the tropics and subtropics.

Some of these Bonsmara cows were selected for longevity, fertility and functional efficiency, and in some instances, we have cows that are 17 years old now that have had 15 calves. The heavier ones weighed over 600 pounds at 8 months and the lightest weighed 450 at 8 months. Any animal which shows hereditary weakness or a point of lower resistance is culled. The bulls used in the selection and breeding work at the Mara Research Station to establish the Bonsmara breed have to be functionally efficient. They must be able to serve 50 or more cows in a 2½-months breeding season. They are sexually active and highly fertile.

In the subtropical, semiarid regions of the Transvaal Bushveldt, those animals which degenerated will be replaced by Afrikaner types and Bonsmara types tropically adapted. The livestock production policy in South Africa is based on the regionalization of breeds and types. That is, the climate is carefully mapped and the breeds of livestock which should be used or bred in a particular area are determined by the climatic conditions of a particular environment and the corresponding environment where the breed originated.

It is certain that in our breeding programs we have to consider the altitude, soil pH, temperature, radiation, light, humidity, the interaction of those factors on the natural vegetation and how the cattle will react to the total environment. Only those animals which can survive and breed regularly in those areas in which they are placed will be of economic importance.

This excerpt is from The Wortham Lectures in Animal Science. You can order a hard copy here:

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