HISOTRY OF BREEDING LIVESTOCK THE STUDY OF REPRODUCTION
2 I. Introduction to Breeding Livestock
A. History of livestock breeding of all four major domestic species is 1000s of years old.
1. This past breeding performance can be defined as Controlled Breedingwhich means giving direction to what we want the outcome to be.
2. It likely began with the OX- fossil bones found in Asia indicate this animal was around 3 to 4 million years past.
a. 6 tall horns like a goat at 6 to 7 feet and grazed on twigs and shoots of trees as well as grass. (pg. 3 AN. Sc. Hus. By Blakely.
3. Also Old Stone Age 8000 to 10000 years B.C.. No domestication at this time due in part to some kind of superstition. They did kill and eat those they could catch and those that died or were killed by other animals.
4. New Stone Age 6000 to 8000 years B.C..
a. Began some domestication of cattle.
b. A change from Hunter to Husbanders.
c. The Major beginning of the study of Animal Science.
5. Neolithic Age 4000 to 6000 years B.C..
a. Domestication of sheep and swine in about 4800 B.C..
b. Also a horse about 3 tall in North America Continent but became extinct before Columbus arrived here.
6. Columbus to America in 1492
a. His 2nd voyage In 1493 he arrived with a number of cattle.
b. This followed with numerous importations of cattle to U.S. Mexico etc.
7. It is believed that all of our current U.S. Cattle are actually descendents of the OX.
5 II. What has controlled breeding done for us
A. It has determined the direction that our cattle are going to be designed for..as follows
1. The size of our cattle a small Jersey and a large Holstein a small Angus and a large Limousine.
2. More muscle and less and less fat.
3. Increase in more Milk Protein.
4. Less cholesterol in eggs we consume.
5. Longer wool in sheep.
6. Increase in multiple births in some species such as in swine and sheep not so much in beef and dairy.
7. Tremendous growth in feed conversion and feed efficiency.
8. Major increase in milk production and rapid growth in poultry meat and number of eggs. (more change in dairy and poultry)
B. The animal breeder has 2 basic tools to work with
1. Selection based on Type
a. Visual observationphysical appearance or what you see on the outside of the animal.
2. Selection based on Performance
a. What is happening inside of the animal that we cannot see.
b. PROOFas a result of testing for performance feed trials records of production change in genetics.
c. Performance takes into account numerous specific areas
1) Feed conversion (lbs. Feed / lb.gain)
2. Pounds gained per day.
3) Gallons milk per day.
4) Fertility improvement.
5) Longevity changes.
6) Large middles for milk cows.
d. Success depends on your knowledge of the tested facts and how you use them.
7 III. Controlled breeding is both an ART and a Science
A. ART..A skill in performance acquired by experience a knack for having success. Same as the Eye of the Master.
1. Rule of thumb.
2. Native intelligence.
3. Learned by accident or chance by trial and error.
4. What your parents did.
5. Not what you learned in school but rather by just getting out and doing it.
a. Getting involved.
b. Shoveling manure.
c. Milking at 300 a.m.
d. Practice judging and clipping.
e. Seeing as many different cattle and places as you can.
f. No substitute for The School of Hardknocks.
B. Science..Knowledge of the truths as tested and found correct (especially past 50 years or so).
1. Critical for the success of todays dairyman. (hard work one-time is all you had to do but not today)
2. Education in
a. Feeding and nutrition
b. Operating computers
c. Understanding genetics and heredity
d. Reproduction conception and parturition
e. Health and diseases
f. Bull selection and mating
g. Milk production and secretion
3. Both are still neededif you had to choose then the Science would out weight the Art.
9 IV. Introduction and History of Reproduction
A. Aristotle (384-322 B.C.) wrote the first scientific paper on embryology.
1. He was so far ahead of his time not much was added to his writing on reproduction for almost 2000 years.
2. He postulated that embryos formed from the menstrual blood of their mother. Of course this is where he was in error.
B. In the mid 1600s to the mid 1700s several discoveries were made with the help of microscopes.
1. Disproved Aristotles theory of the fetus arising from the menstrual blood in 1668.
2. The ovarian follicle was described in 1672
3. Spermatozoa was observed in 1677.
4. Study of chick embryo development began.(1759-1769)
5. Preformed animal theory existed in sperm cell.
C. 1800s time of discovery.
1. Pasteur proved that bacteria reproduced by cell division.
2. Driesh in 1900 separated daughter cells of a fertilized egg and showed that they could develop into an embryo.
D. Reproduction has at least three purposes
1. Perpetuation of the species.
2. To provide food.
3. Genetic Improvement.
12 V. Genetic Improvement
A. Genetic improvement is accomplished by selecting males and female with superior transmitting ability as parents of new generations.
B. The rate of genetic improvement depends upon
1. Variation genetic variation among a population.
2. Heritability or Genetic Variation measure of the transmitting potential of a trait.
a. Ranges from 0 - 60 heritability
1) Milk Production 25
2) Litter size in pigs 5 - 10
3) Fertility in Cattle 5
3. Environmental Variation trait expressed due to environment.
4. Selection intensity stock kept for breeding/not culled.
5. Generation interval Length of time from birth until that generation gives birth.
C. Artificial Insemination
1. A tremendous impact especially in beef and dairy cattle has been made due to A.I. and the data collection evaluation and interpretation by USDA etc.
D. Other reproductive processes that have been or may be used as genetic tools are
1. Frozen Semen
2. Separation of Male/Female producing sperm
3. Synchronization of estrus
5. Embryo Transfer
6. Storing embryos
7. In vitro fertilization
8. Environmental influence on puberty
9. Splitting and cloning embryos
10. Transferring genetic material
What Is the Best Animal
You should understand
The difference between traits and phenotypes.
The concept of interaction of system components
The difference between a genotype by environment interaction and an environmental effect.
How knowledge of interactions involving genotype helps us determine breeding objectives.
The difference between populations that are genetically adapted and populations that are environmentally adapted.
How seedstock producers differ from commercial producers and in what animal industries these terms are meaningful.
The industry influences which cause distortion in breeding objectives.
How correctly defining an end user and understanding the end users system leads to appropriate breeding objectives.
Why directional change in a trait is not always desirable.
How Are Animal Populations Improved
You should understand
The difference between the two basic tools of animal breeding selection and mating.
How selection works i.e. how selecting parents with better breeding values improves future generations.
The difference between phenotypic selection and other forms of selection.
How heritability influences the effectiveness of selection.
The importance of prediction of breeding values.
The concept of accuracy of prediction.
How information on relatives increases the effectiveness of selection.
The difference between simply-inherited and polygenic traits and how selection differs for each.
The difference between complementarity and hybrid vigor.
Why mating systems used by commercial producers are often different from those used by seedstock producers.
How selection and mating can be interdependent.
The combined roles of selection of individuals between-breed selection and mating systems in improving the genetic merit of populations.
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