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The Value of Linear Classification in Boerboels

  Written by Kenny van der Merwe

Introduction

Phenotypic improvement of domestic animals has been around for at least 2000 years.

Selection in breeding programmes focusses on three areas: economical, functional and aesthetic traits. In dogs, the initial focus was on functionality, which in later years shifted to aesthetics in many dog breeds as the need for working dogs diminished. SABBS strives for a balance of functionality, health, and aesthetic traits in its appraisal of Boerboels.

The classification of animals according to the traits they exhibit, proved to be the fastest way of improving multiple traits in the least number of generations. With known classification points, a breeder can make informed decisions regarding the use of an animal for corrective mating.

The Best Linear Unbiased Prediction (BLUP) method of classification represents a modern scientific approach to the classification of animals for breed improvement. Through BLUP, these animals can receive breeding values for the different traits that will contribute to even faster genetic progress through informed targeted selection.

In adopting the BLUP classification system, SABBS once again places itself at the forefront of scientific dog breeding practice.

Why measure?

In 1980, the USA implemented a linear classification system for other breeds, which holds the following advantages compared to the old system of subjective assessment:

  • It is more accurate than the old system because a characteristic is described numerically;
  • This numerical value is distributed between two biological extremes;
  • The linear system describes only one measurable characteristic at a time, and not a composition of characteristics as in the old system, and
  • The system represents an objective measurement of characteristics and not a subjective judging.

Characteristic of a linear trait

  • The description of a linear trait is as follows:
    • The trait must have a biological range.
    • The trait must be heritable.
    • The trait must have variance.
    • The trait must be focused on a working dog.
  • Linear classification is merely a description of a trait.
  • Degree rather than Desirable is recorded.
  • Variation within the population
  • Each linear trait should describe a unique part of the dog which is not covered by a combination of the other linear traits.

Scale of measurement

  • All traits are measured on a scale from 1 to 9, e.g.
    • 1 is a very small dog and 9 is a very big dog
    • 1 is a very straight angulation and 9 is excessive angulation
    • 1 is a dog with weak pigmentation and 9 is a dog with strong pigmentation
    • 9 is not always the ideal
  • Dogs are inspected, classified and assigned grades/scores ranging from 50 – 97 points or %.

The most common scale for mature dogs is:

  • Excellent 90 +
  • Very Good 85 – 89
  • Good 80 – 84
  • Fair 75 – 79
  • Poor/Insufficient 50 – 74

The final class and score is derived from a breakdown of the main functional areas of the dog.

Next: Description of each trait