Identification of a line of sheep carrying a putative autosomal gene increasing ovulation rate in sheep that does not appear to interact with mutations in the TGFB superfamily A Short title: Putative gene increasing ovulation rate in sheep Summary Sentence: Davisdale sheep carry a putative major autosomal gene increasing ovulation rate that does not appear to be linked to the transforming growth factor beta superfamily.

Sheep lines with mutations in single genes that have major effects on ovulation rate have been very useful in gaining a better understanding of pathways important in controlling follicular development and ovulation rate. To date however, all known mutations are in the TGFB superfamily. Ovulation rates were measured in 720 progeny of 20 rams that were descendants of a single prolific ewe. Evaluation of ovulation rates of daughters of closely related sires suggests the presence of a segregating major gene Fecundity Davisdale (FecD) that increases ovulation rate between 0.4-0.8 in heterozygous daughters. Key features of mutations in genes of the TGFB superfamily pathway, such as synergistic interactions with other family members, infertility in homozygous carriers and increased responsiveness to exogenous gonadotropins, were not observed in this line thus the mutation does not appear to be acting in the TGFB pathway. Hence, there is likely a novel mutation being carried in this line of sheep that alters ovulation rate. Thus, future identification of the causative mutation may provide new insights into regulation of follicular development and ovulation rate.