Term
| A breeder has to decide... |
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Definition
1: which individuals would become parents of the next generation through artificial selection
2: how many offspring per parent would s/he generate
3: which females would be bred to which male. |
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Term
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Definition
-random mating
-assortive mating |
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Term
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Definition
| A mating system in which mates are chosen at random and each male and female has an equal chance of mating. |
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Term
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Definition
| The mating of either similar individuals (positive assortative mating, e.g. large individuals) or dissimilar individuals (negative assortative mating, e.g. large and small individuals). |
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Term
| some combination strategies |
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Definition
-crossbreeding
-inbreeding
-line breeding |
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Term
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Definition
| Mating of sires of one breed, strain or line to dams of another breed, strain or line. |
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Term
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Definition
| Mating of individuals related by ancestry. |
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Term
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Definition
The mating of individuals to maintain a substantial degree of relationship to a highly productive ancestor(s) or group of ancestor(s).
-produces mild inbreeding
-example: sire may be mated to some of his daughters to produce more sons closely related to him than if he mated with other females
-sometimes considered as a useful insurance against loss of a sire from sudden death |
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Term
| some consequences of inbreeding |
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Definition
1. Increases homozygosity and reduces heterozygosity. Inbreeding increases uniformity within a line or breed.
2. Expresses deleterious (lethal) recessive alleles with major effects
3. Reduced phenotypic performance. |
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Term
| some deleterious (lethal) effects that can result from inbreeding |
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Definition
-twisted neck
-blindness
-etc. |
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Term
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Definition
| reduction in phenotypic value as a result of an increase in inbreeding level. |
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Term
| the genetic basis of inbreeding depression |
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Definition
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Term
| what decreased heterozygosity does to phenotype |
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Definition
| reduces the contribution of dominance variation to the phenotype |
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Term
| In general, Inbreeding tends to reduce... |
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Definition
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Term
| Relationship between inbreeding and fertility in broiler breeders |
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Definition
inversely related
greater inbreeding means less fertility |
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Term
| opposite of inbreeding depression |
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Definition
| "hybrid vigor" or heterosis |
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Term
| “HYBRID VIGOR” or HETEROSIS |
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Definition
| Change in performance of offspring or progeny population over that of the parental populations |
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Term
| Hybrid vigor or heterosis results from... |
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Definition
1: increased heterozygosity
2: Masking of expression of unfavorable recessive alleles |
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Term
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Definition
| Traits that relate to an animal’s ability to survive and reproduce. |
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Term
| how to calculate heterosis |
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Definition
| Heterosis = ((Average of crosses - Average of Parents) / (Average of Parents)) x 100% |
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Term
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Definition
| Mating of unrelated individuals |
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Term
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Definition
1. To utilize heterosis
2. To take advantage of breed, strain or line complementarity. |
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Term
| genetic basis of heterosis |
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Definition
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Term
| common procedure to estimate heterosis in practice |
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Definition
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Term
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Definition
| basically crossing of lines, strains or breeds |
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Term
| example of a diallele cross |
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Definition
[image]
this is for 3 strains |
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Term
| General Heterosis or General Combining Ability (GCA) |
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Definition
| GCA = (((crossbred average) - (parental average)) / (parental average)) * 100 |
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Term
| Specific Combining Ability (SCA) |
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Definition
| Heterosis between lines or strains |
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Term
| how to calculate specific combining ability (SCA) |
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Definition
example:
SCA = ((((AB + BA) / 2) - ((AA + BB) / 2)) / ((AA + BB) / 2)) * 100 |
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Term
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Definition
| The fact that some lines combine well together |
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Term
| some mating systems that cause inbreeding, but cause no heterosis |
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Definition
-Self fertilization (plants)
-Full-sib mating/parent-offspring
-Half-sib mating
-First Cousins |
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Term
| mating system that causes no inbreeding, but also no heterosis |
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Definition
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Term
| some mating systems that cause no inbreeding, but cause heterosis |
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Definition
-Outbreeding
-Crossbreeding
-Species crosses |
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Term
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Definition
- within a breed
- strain or line crossing |
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Term
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Definition
| - breeds within a species |
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Term
| potential problems of species crosses |
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Definition
-fertility problems
-chromosome incompatibility |
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Term
| Crossbreeding is designed to take advantage of... |
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Definition
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Term
| In poultry, lines are crossed to... |
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Definition
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Term
| 2 reasons lines are crossed |
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Definition
-partly to utilize heterosis to improve reproduction
-partly to combine the different characteristics for which the lines were previously selected |
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Term
| reproductive traits that can be improved by crossing lines |
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Definition
-fertility
-hatchability
-viability |
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Term
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Definition
A highly inbred line of animals that is nearly homozygous in all desirable alleles is used as a test population. Males of this inbred line are usually mated to females of a “new” line
[image] |
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Term
| Reciprocal Recurrent Selection |
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Definition
Instead of using a test line for mating, two lines are mated
[image] |
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Term
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Definition
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