|
|
|
|
The Graphic Below Indicates The 22 Points Considered for Linear Classification
The Components of Linear Classification In a first step, five partial notes are calculated. They concern the following criteria:!. Size; 2. Muscular Development; 3. Meat Type (or skeletal conformation); 4. Stance; 5. General Appearance (Look). 1. SIZE Only the score for the height (H) is used. Added to fifty, it gives the corresponding partial note. A bull, whose height at withers is 2 cm above expectation for his age, has 30 as score for height and 80 as partial note. A partial note of 75 means a height equal to expectation. 2. MUSCULAR DEVELOPMENT The components are the scores for the muscular development of the shoulder, of the top, of the thighs (side and rear views). As the respective contributions of the regions to the total amount of lean, the following weighting was adopted: 1:1:2:2. The weighted sum is divided by six and the result (M) added to fifty to give the corresponding partial note. A cow whose scores for muscular development are: 34,34,40,36 will have 86,7 as partial note for muscling. 3. MEAT TYPE OR SKELETAL CONFORMATION The traits involved are: chest and pelvis widths, rib shape, slope of the rump, tail set. Knowing the economic importance of the width's criteria, the following weights are used: • 2:2:1:1:1. The weighted sum is divided by 7 and the result (T) added to fifty. • If these five scores are: 34,40,25,36,25, the resulting partial note will be: 83,4. 4. STANCE The animal stance is described by the following traits: top line, fore legs, hind legs, hocks. For each of these traits, the score of 100 corresponds to a correct position. Therefore, any deviation (plus or minus) from 25 is unwanted. These deviations from 25, sign ignored, are added and their sum subtracted from 100 what gives the corresponding partial note (S). If these scores have the following values: 22,34,16,35, the partial note will be: (100-3-9-9-10) =69. Moreover, in case of deviations, knuckle, sagged knee, or sickle hock, penalty points are given. That is the way that the stand score is worked out. 5. GENERAL APPEARANCE This note is intended to appreciate the balance, the harmony of the animal and how it places in relation to the true type. It is not a linear score as defined above. The classifier assesses the general appearance on a scale of 20 points e.g.: 14/20. The note is multiplied by 5 (total 100) and the partial note is: 70 (L>. THE FINAL NOTE This note is out of a balancing between the different partial notes, and is calculated to a maximum of 100 points. Its goal is to cross the phenotypic value of the animal, with respect to the requirements of economical profitability. However, one must be careful with its importance in breeding selection, because it can hide some weakness of the animal.General Notes With Regard To Linear Classification Animal Model The animal model takes into account all of the animals in the population. All males and females have their estimated genetic potential evaluated. Taking into account the females in the pedigrees makes it possible to avoid the errors in estimation in the bulls, by taking due consideration to preferential couplings. To think that the animal is used randomly in the population is incorrect and it is necessary to hold account of this reality. Moreover, the genetic potential of the young animals which is primarily estimated on its ascent must take into account the potential of the mother because the dam contributes, equally to sire, when calculating the animals genetic value. The model for the multi characteristic values are calculated by the taking into account the relations (correlations) which exist between the various characters of linear quotation BBB. This method has several advantages: it makes it possible to consider the missing data, to reinforce the information of a character by the knowledge of the other characters which are directly linked to them and to obtain evaluations with more reliability for the same number of descendants. INDEX ON DESCENDANTS Official and to be published, the genetic values (Index) of a bull must meet the following conditions: to reach a threshold of repeatability (precision) higher than 70.% for the final note with at least 20 females taken from a in minimum of 5 different herds. The threshold of publication thus remains identical to what was done previously. Information published relates to the whole of the criteria included in linear quotation BBB INDEX ON ASCENDING As well as the official indexes, predictive indexes estimated on the basis of ascending order and of the collateral ones are also published. For those, the minimum threshold of repeatability is 35 %. The precision of the estimate may appear weak for this kind of index but these are the best possible estimations available for the genetic potential of the bull. These are estimations are made for young bulls which do not yet have descendants that have been classified. Lastly, certain young bulls whose sire and dam do not have an official evaluation or of which the repeatability of the index estimated on ascent does not reach 35 %, do not have indices published. For those, only the linear classification of the bull is published.
|
|
|
