ANSI 3433 Lecture Notes - Lecture 4: Selective Breeding, Zygosity, Heterosis

121 views5 pages
27 Nov 2016
School
Department
Course
Professor
How Are Animal Populations Improved?
Purpose of Animal Breeding is to improve populations.
Two Basic Tools of Animal Breeding (Decisions):
- Selection process that determines which individuals become parents, how
many offspring they produce and how long they remain in the breeding
population
- Mating determining which males will be mated to which females
Mating is distinctly different than selection
In selection we are picking a group to become parents; in mating, you match males to females
from the selected group.
Dam female parent
Sire male parent
Selection
- Results in long-term change
- two types:
o natural great evolutionary force fueling genetic change in all living things.
Affects wild and domesticated animals; for example, all animals with lethal
genes are naturally selected against
o artificial under human control, the type of primary interest to animal
breeders
We focus on artificial selection, but cannot ignore natural selection.
Artificial selection has two aspects:
- Replacement selection deciding which animals will become parents for the
first time. (replacing the culls) not just young aials, exaple……a AI sire.
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 5 pages and 3 million more documents.

Already have an account? Log in
Artificial Insemination (AI) a reproductive technology in which semen is collected from males,
then used in fresh or frozen form to breed females.
- Culling determining which animals will no longer remain parents.
Both determine which animals reproduce, and which do not.
Goal of animal breeding is to:
- let individual with the est gees reprodue, so that the…
- next generation has on average better genes
- over time, frequency of desired genes in the population will increase
Animals with the best genes are the ones with the best Breeding Value. Breeding Value is the
genetic value of an individual as a parent
Phenotypic Selection
- simplest form of selection
- ignores pedigree, performance of relatives. Only info used is the individual
performance of each animal being considered for selection.
- underlying assumption is that those with best phenotype have best genotype
(breeding value) Problem?
Environment cant be evaluated just by looking at the animal. The
environment plays a large role!
Measuring Performance
Selection requires performance testing
- Varies among species
- Recording phenotypes for traits within contemporary groups
- Systematic measurements of performance (phenotype) in a population
- Primarily done in purebred seedstock programs
Contemporaty group a set of animals that are same sex, managed alike, close to the same age
and given the same opportunity to perform in the same environment. (submitting individual
performance measures on animals for genetic prediction requires proper contemporary
grouping)
- Use additional information to increase accuracy of selection, such as
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows pages 1-2 of the document.
Unlock all 5 pages and 3 million more documents.

Already have an account? Log in

Get OneClass Notes+

Unlimited access to class notes and textbook notes.

YearlyBest Value
75% OFF
$8 USD/m
Monthly
$30 USD/m
You will be charged $96 USD upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.