Ovulation rate and litter size of prolific Inverdale

Two mutations, Inverdale (FecXI) and Hanna (FecXH), that affect ovulation rate in sheep have been identified at the FecX locus. Ewes with two copies of the FecXI or FecXH alleles are known to be infertile, but heterozygous ewes have increased ovulation rate and litter size. Ovulation rate and litter size were compared between heterozygous Inverdale ewes (I+) and heterozygous Hanna ewes (H+). The effect of the FecXI and FecXH alleles on ovulation rate in heterozygous ewes was an increase of 0.80-1.32 compared to non-carriers, and there was no significant difference between the two alleles. Litter size increased by 0.35-0.81, with no significant difference between the two alleles. Consequently, the same breeding strategies can be applied to sheep carrying either allele