T. C. van Stijn, J. M. Penty, G. W. Montgomery

The OarAE101 microsatellite had previously been shown to be linked to the Booroola (Fec^B) gene. Six F₁ Awassi × Booroola rams were typed for the OarAE101 marker. Only 1 of the 6 (ram 120) was heterozygous for the marker; allele F of this marker was linked to the Fec^B allele inherited by this ram from his Booroola Merino sire. 15 daughters of ram 120 inherited the F allele and 7 inherited the other allele (I) of the microsatellite. For daughters inheriting the F and I allele, ovulation rate averaged 2.95 and 1.75 respectively, and mean litter size in the first 3 parities 1.9 and 1.3. The genotype at the Fec^B locus as determined by the marker agreed with the genotype as determined on the basis of ovulation and litter size in 21 of the 22 ♀♀. The litter size of Booroola carrier ewes was 0.6 lambs more than that of non-carriers, and plasma level of FSH in the 2 groups was 3.7 and 1.9 ng/ml respectively.