DAIRY CATTLE BREEDING AND SELECTION

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DAIRY CATTLE BREEDING AND SELECTION

• HISOTRY OF BREEDING LIVESTOCK THE STUDY OF
  REPRODUCTION

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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.

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• 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.

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• 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.

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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)

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• 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.

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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.

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• 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.

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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.

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• 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.

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• 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.

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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.

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• 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
• 4. Superovulation
• 5. Embryo Transfer
• 6. Storing embryos
• 7. In vitro fertilization
• 8. Environmental influence on puberty
• 9. Splitting and cloning embryos
• 10. Transferring genetic material

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• 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.

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• 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.

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• 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.

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• 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.

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• 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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THE END