Genetic evaluation with major gene in Tunisian Barbarine Sheep

The objective of this work was to use the approximate probabilities computed by iterative peeling to include genotype information at the FecX^bar/BMP15 major gene in a prolific line of Barbarine sheep, of which a few animals were genotyped. This line is raised at the experimental station of the Tunisian National Institute for Agronomic Research (INRAT) and a selection program for prolificacy has been carried out since 1979. The FecXbar/BMP15 mutation responsible for prolificacy and ovulation rate was identified, but this information is not considered in the actual selection program of this line. Data consisted of 2794 litter size (LS) records of 1014 females from 1989 to 2019 and 4372 animals in the pedigree. Probabilities for each possible Fec/X^bar genotype for animals with unknown genotypes were estimated based on iterative peeling equations using the Alphapeel software. Then, heritability (h²) and estimated breeding values (EBVs) were calculated with two models: i) a classic model without genotype information, and ii) a model including the imputed genotypes as a fixed effect. All parameters were estimated using the Gibbs sampling methodology as implemented in the TM software, and LS was modeled as a discrete variable. h² was estimated as 0.14 for both models. The correlation between estimated breeding values in both models was 0.99. These results indicate that including FecXbar/BMP15 has no impact on the genetic evaluation for this prolific line. Nevertheless, further work on genotyping a larger number of animals will be required.