Estimation of litter size variability phenotypes in Large White sows

Area of Science:

• Animal Breeding
• Genetics
• Quantitative Genetics

Background:

• Phenotypic variability in traits like total number born (TNB) can impact breeding efficiency.
• Understanding the genetic basis of this variability is crucial for sustainable genetic improvement.

Purpose of the Study:

• To develop new phenotypes for phenotypic variability of TNB in pigs.
• To estimate genetic parameters for these new variability traits.
• To assess the potential for genetic improvement of litter size variability.

Main Methods:

• Utilized a large dataset (246,799 observations) of Large White pigs.
• Employed three animal models (Basic Model, Basic Model with Parity, Random Regression Model) to estimate residual variance.
• Calculated within-individual variance, log-transformed it into new traits (LnVarBM, LnVarBMP, LnVarRRM), and estimated genetic parameters using multivariate models.

Main Results:

• The new variability traits (LnVar's) are genetically the same trait and positively correlated with mean TNB (mTNB).
• Heritability for LnVar's was estimated at 0.021, indicating genetic control.
• A genetic coefficient of variation (GCV_SDe) suggests an 8% change in residual standard deviation of TNB per generation is achievable.

Conclusions:

• Phenotypic variability of pig litter size is under genetic control and can be improved through selection.
• Including both mean TNB and its variability traits in breeding programs is recommended to manage genetic gain and avoid increased variability.