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36 Cards in this Set
- Front
- Back
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What is animal breeding? |
"master plan" to make better animals |
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What is the formula for genetic progress? |
=heritability of a trait X selection differential (reach) / generation interval |
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What is heritability? |
proportion of an observed trait, that is passed on to progeny (offspring) |
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What is a highly heritable trait? |
most of trait is passed on from generation, highly genetically controlled, low environmental influence |
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What is a lowly heritable trait? |
has an environment influence 2. reproduction |
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What is selection differential? (reach) |
average superiority of an individual over the average of the population from which they are selected. How much better are the selected parents then the average? -difference in a specific trait of the selected animal from the average |
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What are the limiting factors of selection? |
1. how much variation in the herd 2.how many must person select 3. price |
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What is the variation in herd? |
more variation, more progress can make. Variation is good from a standpoint of genetic variation |
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How many must a person select? |
more genetic improvement in males because we select fewer of them. (one male for a lot of females) |
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What is generation interval? |
average age of parents when the offspring is born |
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How must we improve animals? |
through planned mating. 1. desire more productive animals (more profit) 2. improve enviornment 3. improve their genetics |
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What is differential reproduction? |
certain animals will produce more offspring then others |
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What is wrong with environmentally improving? |
its gone, not permanent. Improving genetics is permanant |
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How do we choose superior animals? |
1. conformation/ type 2. pedigree 3. performance records 4. show winnings 5.mating ability 6.progeny 7. DNA testing 8. free of genetic defects 9. breeder reputation |
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What is pedigree? |
record of ancestry, showing animal to be purebred |
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What is the best measure for sire selection? |
progeny, but takes time |
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Why is it no recommended to do single trait selection? |
the more you select for, the harder it is to make progress |
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What is tandem selection? |
select for 1 trait in 1st generation -select for 2nd trait in 2nd generation -two traits selected for an alternate generation |
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What is independent culling level? |
used everyday. sets standards as individuals must meet to be kept as a replacement in herd. |
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What is the index merit? |
numerical ranking of animals based on several traits -advantages: easily computerized, can alter index to change herd emphasis -system has balanced selection; doesn't eliminate on single trait |
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What is random mating? |
rarely occurs in domestic animals with exception of dogs and cats -some form in multiple sire pastures -reach in random mating is 0 |
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What is planned mating? |
trying to improve genetics, use better genetics |
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What are the 3 key components to index merit? |
1. traits in index 2. have coefficients/ factors/ weight 3. arithmetical function |
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What is single trait selection? |
making a selection based on one thing |
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What is inbreeding? |
mating of relatives, shrinks the gene pool downfall: increases homozygotic pairs and many genetic defects are homozygotic recessive -used primarily in seed stock division |
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What is line breeding? |
one animal shows up many times in pedigree -only in seed stock not commercial -type of inbreeding |
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What is close breeding? |
breeding many of the same relatives -type of inbreeding |
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What is outbreeding? |
opposite of inbreeding |
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What is straight breeding? |
continued use of same breed |
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What is cross breeding? |
mating of 2 or more different breeds -progeny tends to outperform parents -has greatest effects on lowly heritable traits (reproduction, weight) |
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Why in cross breeding are you apt to see less genetic defects? |
defects come from homozygotic pairs |
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What is planned cross breeding and what are the two types? |
have plan 1. terminal 2.rotational |
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What is terminal cross breeding? |
all progeny are sold, and no female replacements are kept ADV: maximize heterosis, makes more progress DIS: buy more animals in, health risks increase |
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What is rotational cross breeding? |
rotating the breed of sire used (sire=male) -one male, lots of females -keep best females, bring in the males ADV: purchasing only sires, selection pressure of females DIS: more homozygosity of gene pairs and decreases heterosis level -more widely used |
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What is hybrid vigor? (heterosis) |
result of increasing heterogosity of gene pairs ADV of cross breed vs pure bred is hybrid vigor |
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Cross bred is not popular in? |
horses and dairy |
