Genetic evaluation with autosomal and X-chromosomal inheritance

Area of Science:

• Animal Genetics
• Quantitative Genetics
• Livestock Breeding

Background:

• Current livestock genetic evaluations primarily use best linear unbiased prediction (BLUP) assuming autosomal inheritance.
• Emerging evidence indicates X-chromosomal inheritance significantly impacts economically important livestock traits.

Purpose of the Study:

• To extend BLUP methodology to simultaneously account for autosomal and X-chromosomal additive genetic effects.
• To provide a framework for more accurate genetic evaluations in livestock populations with sex-linked trait inheritance.

Main Methods:

• Developed a mixed model equation incorporating both autosomal (a_i) and X-chromosomal (s_i) additive genetic effects.
• Defined covariance matrices for autosomal (Aσ_A^2) and X-chromosomal (Sσ_F^2) additive effects.
• Provided recursive rules for constructing the X-chromosomal co-ancestry matrix (S) and an efficient algorithm for its inverse.

Main Results:

• The proposed method allows for the calculation of BLUPs for both autosomal and X-chromosomal additive effects.
• The study presents a computationally efficient approach to handle X-chromosomal inheritance within BLUP.

Conclusions:

• BLUP can be effectively adapted to include X-chromosomal inheritance, improving genetic evaluations for relevant traits.
• This advancement offers a more comprehensive approach to livestock breeding and genetic improvement programs.