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Inbreeding Genetic Principles |
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Inbreeding is the result of a mating between two related animals. Inbreeding requires that the same ancestors are found on the paternal and maternal sides.
The progeny's inbreeding level depends on the degree of relationship between the parents used for that mating..
Mating results greater than 6,25 % are not recommended in order to maintain reasonable inbreeding levels in the herd or in a population..
Generally, low inbreeding does not bring any problems. It is generally considered that if there are five generations separating the two common ancestors, the inbreeding level is low ((1/2)5 x 100 = 3,12 %).
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Inbreeding calculation |
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Here are the matings to avoid in order to control inbreeding within a population :
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Avoid inseminating a cow with : |
Resulting inbreeding |
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her sire |
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25,0 % |
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a son of her sire |
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12,5 % |
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her grandsire (paternal or maternal) |
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12,5 % |
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a son of her grandsire or a grandson of her sire |
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6,25 % |
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(acceptable) |
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Don't forget, inbreeding is not hereditary!
- Highly inbred individuals who do not have common relatives will produce non-inbred progeny and will benefit from hybrid vigour.
- Two non-inbred individuals who have common relatives will produce inbred progeny.
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Examples :
Aerocerf (15,3 % inbreeding) x daughter of Leader (not related to Aerostar) = 0 % inbreeding
Stormatic (low inbreeding) x Comestar Lausan Black (low inbreeding) = 25 % inbreeding
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Negative effects of inbreeding |
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- For each 1 % of inbreeding, it is estimated that the production of a typical Holstein cow in first lactation decreases by 25 kg of milk, 0,9 kg of fat and 0,8 kg of protein.
- Negative impact on vigour (type decreases by -,03)
- Higher calf mortality
- Poorer growth and reproduction performances
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Positive effects of inbreeding |
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- Increase in homozygote genes, which translates into a more uniform progeny
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Example : |
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