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Oprettet: 20-10-2006

Correction of Linear Assessments of Dairy Cattle

When a classifier assesses a cow, the appearance of the animal at the time of assessment is registered.

The assessment is carried out on a scale from 1 to 9, and defective characteristics might be added, if necessary. All these registrations are saved in the handheld computer.

However, there are a number of factors influencing the appearance of a cow, and it is often difficult to compare animals on the basis of the number of points given during the classification. For example, it is not adequate to compare the stature of a young cow just after first calving with a cow in third lactation, as the first-calver is still growing. When calculating the conformation value, these factors are taken care of, so that different cows can be easily compared.

Correction of Raw Classifications
All cows are corrected to the level of a first lactation cow four months after calving. Cows in first lactation are corrected for days in milk and age at calving. RDC, HOL and DRH are corrected to 28 months as age at first calving, corresponding to 26 months in Jersey. Cows in second and third lactation are corrected for lactation number and days in milk.

The following table shows how the raw classification is corrected in order to be able to compare different cows. Moreover, an example of a cow in third lactation is presented.

Correction Factors for the Calculation of the Conformation Score

1st lactation 2nd lactation 3th lactation
  Example of a cow
Age at Calving Lactation Number Lactation Number
Days in Milk Days in Milk Days in Milk
Hours from milking Hours from milking Hours from milking 

Calculation and Standardisation of Conformation Score for Body, Feet & Legs, and Mammary System
The corrected registrations are summarized into three groups: body, feet & legs, and mammary system. This is done on the basis of weighing factors and optima of the individual breeds.

Calculation of the Total Score
Finally, the three conformation scores for body, feet & legs, and mammary system are summarized into one score for the whole conformation = Total Score.

Publication of Total Score
The Total Score is published on a scale from 60 - 99 with an average of 80 and a standard deviation of 5. The owner receives a print-out of the classification, either per cow or for all cows assessed, at the end of the classifier's visit. The print-out shows the calculated conformation scores plus the Total Score. The various scores are available for and included in different print-outs and statistics, as soon as the classification is included in the National Cow Database.

Sidst bekræftet: 22-10-2015 Oprettet: 20-10-2006 Revideret: 20-10-2006

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Afdelingsleder

Anders Fogh

Avlsværdivurdering, Kvæg


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