Mutations in the leptin receptor gene associated with delayed onset of puberty are also associated with decreased ovulation and lambing rates in prolific Davisdale sheep.

The aim of this study was to determine if single nucleotide polymorphisms (SNPs) in the leptin receptor (LEPR) gene associated with delayed onset of puberty are associated with changes in other reproductive traits in adult ewes. The ovulation rate of ewes homozygous for the SNPs was ~15% lower (PPLEPR SNPs than their wild-type or heterozygous contemporaries. Partial failure of multiple ovulations was also increased (PLEPR had on average 0.

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 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 transforming growth factor beta (TGFB) superfamily. Ovulation rates were measured in 720 progeny of 20 rams that were descendants of a single prolific ewe.

Patterns of expression of messenger RNAs encoding GDF9, BMP15, TGFBR1, BMPR1B, and BMPR2 during follicular development and characterization of ovarian follicular populations in ewes carrying the Woodlands FecX2W mutation.

Woodlands sheep have a putative genetic mutation (FecX2(W)) that increases ovulation rate. At present, the identity of FecX2(W) is unknown. The trait does not appear to be due to the previously described mutations in bone morphogenetic protein 15 (BMP15), growth differentiation factor 9 (GDF9), or bone morphogenetic protein receptor type 1B (BMPR1B) that affect ovulation rate in sheep.

Physiological effects of major genes affecting ovulation rate in sheep.

Genetic mutations with major effects on ovulation rate in sheep were recently identified in two genes of the transforming growth factor (TGFbeta) superfamily and a TGFbeta receptor, namely bone morphogenetic protein 15 (BMP15), otherwise known as the growth differentiation factor 9b (GDF9b), GDF9 and activin-like kinase 6 (ALK6) otherwise known as the BMP receptor type IB (BMPRIB). Animals homozygous for the BMP15 or GDF9 mutations are anovulatory whereas animals heterozygous for BMP15 or GDF9 or heterozygous or homozygous for ALK6 have higher than normal ovulation rates. Immunisation of ewes against BMP15 or GDF9 shows that both are essential for normal follicular development and control of ovulation rate.

Mutations in the genes for oocyte-derived growth factors GDF9 and BMP15 are associated with both increased ovulation rate and sterility in Cambridge and Belclare sheep (Ovis aries).

Belclare and Cambridge are prolific sheep breeds, the origins of which involved selecting ewes with exceptionally high litter size records from commercial flocks. The variation in ovulation rate in both breeds is consistent with segregation of a gene (or genes) with a large effect on this trait. Sterile ewes, due to a failure of normal ovarian follicle development, occur in both breeds.

DNA tests in prolific sheep from eight countries provide new evidence on origin of the Booroola (FecB) mutation.

Recent discoveries that high prolificacy in sheep carrying the Booroola gene (FecB) is the result of a mutation in the BMPIB receptor and high prolificacy in Inverdale sheep (FecX(I)) is the result of a mutation in the BMP15 oocyte-derived growth factor gene have allowed direct marker tests to be developed for FecB and FecX(I). These tests were carried out in seven strains of sheep (Javanese, Thoka, Woodlands, Olkuska, Lacaune, Belclare, and Cambridge) in which inheritance patterns have suggested the presence of major genes affecting prolificacy and in the prolific Garole sheep of India, which have been proposed as the ancestor of Australian Booroola Merinos. The FecB mutation was found in the Garole and Javanese sheep but not in Thoka, Woodlands, Olkuska, Lacaune, Belclare, and Cambridge sheep.

A deer (subfamily Cervinae) genetic linkage map and the evolution of ruminant genomes.

Comparative maps between ruminant species and humans are increasingly important tools for the discovery of genes underlying economically important traits. In this article we present a primary linkage map of the deer genome derived from an interspecies hybrid between red deer (Cervus elaphus) and Père David's deer (Elaphurus davidianus). The map is approximately 2500 cM long and contains >600 markers including both evolutionary conserved type I markers and highly polymorphic type II markers (microsatellites).