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Change in ICBF evaluations for GROW® linear scored MUSCLE and SKELETAL composites
The main reasons for the change from the old BLUP system to a new system were:
The old BLUP system has a number of limitations which had to be addressed:
1. The age range at which animals were scored is too wide and thus affects accuracy of proofs. The new system of scoring under 300 days also entails mandatory weighing which also allows a prediction of growth rate traits and milk yield potential on the dams.
2. Linear score information where a single animal is scored in a herd visit is also used by grouping all the animals in these single scoring sessions into a single herd over a period of time thus assuming similar management practises across all these herds which is a large and inaccurate assumption. Research on evaluation systems in France and the UK revealed a minimum group of 5 was the standard norm.
3. The system only uses information on pedigree animals whereas many herds have also got crossbred animals which could also provide valuable information.
4. The old evaluation only provides genetic indexes on the composite traits for MUSCLE and SKELETAL. Hence breeders do not see the individual trait strengths of the animal scored such as loin development or development of hind quarter which are 2 of the 5 traits in the MUSCLE composite.
5. The old BLUP evaluation is not based on a similar level of evaluation criteria as the Euro-star indexes and is not in tandem with the timing of release of the Euro-star indexes.
6. The old system was only available for 3 breeds. New Percentiles for Linear Evaluations
New percentiles for Linear Evaluations:
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% Ranking
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Old Muscle
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New Muscle
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Old Skeletal
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New Skeletal
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New Functional
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Top 1%
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132
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126
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132
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126
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126
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Top 5 %
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125
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118
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125
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118
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118
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Top 10%
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121
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114
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121
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114
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114
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Top 20%
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17
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110
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117
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109
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109
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Top 40%
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111
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104
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111
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104
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104
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Average
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107
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102
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107
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101
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101
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Main reasons for drop in scale of proofs:
1. Removal of animals which were not scored in a group of 5 from the same farm over a two month period. Bulls which had a lot of progeny in the old system scored in groups of less than 5 will be affected more through re-ranking for more information on individual bull changes go to http://www.icbf.com/services/evaluations/beef.php
2. More accurate adjustment for management group. Previously animals scored within a 6 month period were allowed to be grouped together. This was reduced to a 2 month period in which animals could be put in the same contemporary group.
3. The old BLUPs worked off a French heritability of 40% for Muscle and Skeletal traits. The new genetic parameters estimated with Irish data caused a reduction in heritability to 0.34 for Muscle, 0.28 for Skeletal and 0.08 for Functional traits. This reduction in heritability would also cause a reduction in scale of the proofs as less of the variation in scores is being attributed to genetics.
The new rules to be applied for an animal to make it into the new evaluation are as follows:
Evaluation rules:
1. Animals must be scored & weighed in a group of 5 (may include commercials) and must be at least 150 days of age and less than 300 days of age for their information to be included in the €uro-Stars and linear type trait evaluations.
2. The sire of all the animals in the scoring group must be known.
3. Animals submitted for scoring which were purchased (not born in the herd) must be on the farm for a minimum of 2 months prior to scoring.
4. Only animals out of a beef breed of sire will be accepted.
5. Animals with a condition score of 1 (scale from 1 to ten) will not be used in the evaluation as this is an indication the animal is malnourished or sick. The variation in condition score within the group of animals scored will also be examined by the scorer to ensure no extreme preferential treatment is carried out.
6. Information relating to the ancestry of animals will be updated in the evaluation once every 4 months along with the routine €uro-star evaluations. Hence breeders need to ensure the pedigree details are correct at or before the time of scoring.
7. Evaluations will be run once a month. For each monthly evaluation the cut-off date after which animals scored will not be included will be 15th day of the month.
8. New evaluations for linear and ¤ur o-Stars will be available on the 1st week of the following month
The new Muscle, Skeletal and Functional composites will be presented on a base of 100 and standard deviation of 10 which is similar to the old way of presentation. All three indexes are a within breed comparison and are compared to all pedigree animals in the breed born in the last 5 years. The relative ranking of the animals (% Rank) will also be presented to show where the animal ranks in the breed.
Docility
The old docility evaluation has been replaced by a new docility evaluation which combines the linear score docility and the docility recorded through the Suckler Welfare Scheme. Where an animal is linear scored and also has a score from the Suckler Welfare Scheme then the linear scorer docility is used. The new docility figures will be available for all breeds. The figures will be presented as a plus or minus value based on a scale of 1 to 5. The more positive the value the better the docility ranking. The relative ranking will also be available through the % Rank and a five star rating on a within and across breed basis.
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