AGB 121: Principles of Animal Genetics and Population Genetics (2+1)

USES / APPLICATIONS

• From the animal breeder’s point of view, genetic correlation is important, because of the change brought by selection. It is important to know how the improvement of one character will cause simultaneous changes in other character. This is called correlated response brought in the character not selected for (may be positive or negative). Selection for a character affects favourably or adversely the other characters if they are genetically correlated.
• Example:
  • Milk yield and butter fat % are genetically negatively correlated
  • Egg production and egg size are genetically negatively correlated
  • Here selection for milk yield in dairy cattle reduces the fat percentage. Likewise selection for egg yield in poultry reduces egg size. Therefore the reductions in other economically important traits through genetic antagonism need to be taken note in designing selection programmes.
• Uses of genetic correlation are
• To predict the direction and magnitude of response of correlated character during selection. The knowledge of genetic correlation is useful to forecast reduction in the correlated traits in single trait selection if they are negatively correlated.
• Indirect selection: Sometimes certain traits are difficult and costly to measure. So these traits can be improved by selecting easily measurable trait by correlated response.
• The r_P and r_A are used in the construction of selection indices .