Intro to Animal Science
Study Guide Exam 1
• Chapter One Importance of Animals
We rely on animals for food, clothing, knowledge, energy, power, status, transportation, companionship, entertainment, service and capital
Development complex of the human brain: we originally ate a plant base diet, so had a large gut. Once we found out how to eat and digest meat, out gut shrank and digestion was less labor intensive, and also took less energy. This energy then went to the brain.
•Meat/ dairy consumption: our diet should contain low-fat meat as well as dairy products such as milk
Yogurt and cheese.
In the US, 99% consume animal products (this includes eggs, honey, gelatin, etc.)
27% of the US’s calories (on average) are from animal products, excluding animal fats
17% of the worlds calories (on average) are from animal products excluding animal fats. If you want to learn more check out What are the excellent sources of vitamin c?
Meat and milk is the greatest contribution to animal products consumed in the us and world wide
Developed countries consume at least twice the amount of meat and egg product when compared to least developed countries, this pattern of economic status influencing food choice is also seen in each individual country as well. We also discuss several other topics like What is the distinction between physical and chemical changes/properties?
Worldwide goat is the most consumed meat
Today chicken, beef and pork are the most consumed meats in the US, with pork being the number one consumed meat.
Milk consumption has decreased overall but cheese consumption has increased.
Milk in the us is mostly consumed from cattle, but in India over 60% of people get their milk from water buffaloes.
Other animals used in milk production are: yaks, goat, sheep, camel, mare, sow, reindeer and llama If you want to learn more check out Does the sun move?
•Other uses for animals beyond food:
Fiber: Many types of fibers can be collected from animals including wool, from sheep, mohair and cashmere from goats, angora from rabbits and other fibers from llamas, alpacas, camels and yaks.
Many animal fibers are being replaced by cotton or synthetic fibers.
Globally, wool is the most used animal fiber, representing 5% of the textile fiber production. We also discuss several other topics like What is megasporogenesis?
Land management and transportation: animals all across the globe are used as erosion control, range or pasture management including plant diversification and noxious weed control.
Many grazing animals can be sustained on land which otherwise would have not been cultivated
Draft animals are vital especially in Africa and Asia, where most of the land is not able to be cultivated by machine. Up to 25% of the land relies on animals to cultivate the land.
Transportation using animals is also important; some areas in the united states have limited number of cars so rely on animals for transportation.
In Sub-Saharan Africa, donkey driven carts have been on the rise, and are expected to stay in demand in the future.
Some animal fats can be refined and used as fuel for cars.
Research: animals have contributed to over 50% of the scientific discoveries and 2/3 of the Nobel piece prizes
Rats and mice are the most used animals in research, but other animals used are non- human primates, dogs, cats, pigs horses, etc.
By FEDERAL LAW animal testing MUST be conducted before human trials are conducted.
Rats and animals are used due to convenience; they take up a small amount of space, reproduce fast and are easy to maintain. If you want to learn more check out What is india?
Pigs have contributed quite a bit too, due to our similarities with them; we have had heart studies and obesity studies done on pigs which correlate to humans. This also includes heart disease.
Sheep studies have been used in fetal development studies, and chickens are helping in studies with ovarian cancer.
It is important to use animals for research; no animal is a perfect model for humans. The results we get from these studies may give us insight to possible results, but until the clinical trials are conducted there is not “for sure” reaction.
Chapter Two Domestication:
Humans are not solely responsible for the domestication process; evolution and genetics have some place in.
the first stage of evolution is the longest stage of development, and is considered the origins of animals and their continuing ability over time, while domestication is considered fixed evolutionary behaviors and production is the most recent stage of development through selective practices.
All domesticated animals have similar traits, which allowed humans to interrupt their natural hierarchy, also some animals are impossible to domesticate (note the difference between feral, wild, tame and domesticated).
•Origin of animals: Todays animals appeared during the Cambrian period (540 million years ago), also known as the Cambrian explosion.
Mammals appeared during the Triassic period (250 Million years ago) Birds appeared during the Jurassic period (150 Million years ago)
Humans appeared during the tertiary period (65 million years ago) which was also viewed as the period of land bridges that linked north America to Asia. We also discuss several other topics like What hormone stimulates milk production in a woman's breasts after she gives birth?
Pig, cow and horse ancestors appeared about 53 million years ago.
Principles of Evolution: Evolution is the process by which changes occur over SUCCESSIVE GENERATIONS; BOTH animals GENETICS and its ENVIRONMENT are important for evolution.
Biologist whom started to study evolution include, Charles Darwin, William wells, Patrick Mathews and Alfred Wallace.
Animals will evolve as the inherently possess the ability to vary, reproduce in excess, and are exposed to a continually changing environment.
Darwin created the idea of natural selection, and that animals can gradually change morphologically over time to adapt to their environment.
Natural selection also works on existing genetics, and cannot introduce variation.
Natural selection is increased however, because animals in general have a tendency to reproduce and overpopulate beyond environmental sustainability.
Adaptations are modifications that are maintained through natural selection.
Horses are a great example; they use to have feet, but slowly their feet developed into hoofs
Evolution during domestication: during domestication an animal’s SOCIAL environment is the primary force acting on existing variation.
Despite only aiming for social, some physical attributes still follow such as, floppy ears, curled tails, white head spotting, this is due for selecting for a single trait.
The original trait being selected for was tameness and docility towards humans, but it originated with natural selection. Artificial selection would play a role later in the domestication factor.
Fox-farm experiments showed the effects of artificial selection, and how fast artificial selection can take effect.
Domestication moves beyond taming: most animals are unable to be domesticated; for example, Of the 148 hooved animal species, only 14 are currently domesticated.
Fish are still working on being domesticated, while some animals we keep as pets are not considered domesticated such as snakes and other exotics.
According to DARWIN, domestication required breeding of animals in captivity, was goal oriented, increased reproductive success of the animal, brought about atrophy or reduction in organ systems, enabled greater demonstration of adaptability, and was a process facilitated by subjugation to humans.
Tame is the acceptance of humans for a brief period of time, and will not last generations. It is only temporary. The offspring of tame animals will show wild behaviors even if their parents do not. Genetically there are absence of domestic markers.
Feral animals are animals where were at one point domesticated but through generations of not having human contact have started to go towards their wild state.
Major species of domesticated individuals include cows, pigs, sheep, horses and goats. Minor species include donkeys, water buffalo, reindeer, llama alpaca, camels, and yaks.
Behaviors that support domestication are large social groups with a hierarchal structure, promiscuous mating with male dominance, signal reproductive readiness through postures, prosocial young, short flight distance and low reactivity to humans, herbivores or omnivores, low stress response to confinement.
Domestication where and when?:Wolfs were one of the firsts animals to be domesticates, estimated about 17-15 thousand years ago.
Domestication events tended to occur where food was more scarce, and hunting was not always most optimal.
In the tropics very few if no domestication events occurred because the climate allows for hunting all year round, and animals didn’t have to connect with humans.
Most of the evidence of domestication occurred towards Mesopotamia.
Pigs have had the most domesticated events out of all the domesticated animals.
The stages of domestication:
1. Control over animals in the wild
2. Control over captive wild animals
3. Breeding of captive animals
4. Morphological changes in captive animals