1
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2
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- Interbull combines yield evaluations from 27 national Holstein bull
populations.
- Estimated genetic correlations between evaluations from different
populations are applied.
- Results are reported on the scale of each participating country
organization.
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3
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- Full brothers are expected to have the same genetics on average.
- Full brothers with daughters in different countries should have the same
MACE evaluations (on average).
- Do full brother evaluations reveal country bias?
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4
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- May 2005 Interbull evaluations of Holsteins for milk, fat, and protein
yields, and SCS
- Eligible bulls
- ≥1 eligible full-brother
- Daughters in only one eligible country
- Eligible countries
- Represented in ≥25 multi-country families
- 18 countries for yield
- 15 countries for SCS
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5
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6
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7
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8
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9
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- Full-brother family (absorbed)
- Country of bull daughters
- Analysis of MACE evaluations on the US scale
- Difference between evaluations based on foreign daughters and those
based on domestic (US) daughters
- Evaluations on several other country scales also analyzed
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10
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- Overall significance for country differences on all country scales for
yield traits
- Overall, no significance for SCS
- For SCS, South African bulls significantly disadvantaged on all scales
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11
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12
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13
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14
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15
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- Genetic correlations
- Parent averages (completeness and phantom grouping)
- National animal model vs. sire-MGS MACE
- Preferential treatment
- Pre-selection (markers, etc.)
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16
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- Apparent biases for yields but not SCS
- Some countries appear disadvantaged while others are favored across all
country scales
- Caused by shortcomings in national systems or international system?
- Source of biases unknown and may be different for different country
pairs
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