AGB 211: Livestock and Poultry Breeding (2+1)

COMPUTATION OF RELATIONSHIP COEFFICIENT

• Genetics is defined as the science which seeks account for the resemblances and difference exhibited among individuals related by descent. The idea of relationship is familiar to all. Like father like son. First scientific attempts to measure the degree of resemblance between different kinds of relatives were made by Sir Francis Galton.
• Relatives resemble each other in various degrees because each off spring gets half of the genes which its parent had. Relationship between two individuals is simply probability, because they are related by descent, they will be alike in more of their genes compared to unrelated members of the same population.
• The parent off spring relationship is the simplest. The parent offspring relationship is 50% in populations where there is no inbreeding. It is because each offspring receive half of its genes from each parent.

Coefficient of relationship

• The coefficient of relationship between two individuals is an expression of the probability that they possess duplicate genes, because of their common line of descent, over and above those found in base population. Measuring relationship is the probability that the two related individuals will have duplicate genes because they are related by descent.
• Relationship are of two different kinds
• Direct relationship: Relationship that can be traced in a direct patheay of descent from an ancestor to a descendant.
• Collateral relationship: Two individuals have an ancestor in common and so each may have inherited the same gene from that ancestors.