Bioscientifica Proceedings

Placental insufficiency results in fetal loss, low birth weight, stillbirth, preweaning mortality and poor growth. Placental development begins at conceptus elongation, which is a primary factor controlling the size of the placenta. After elongation, the allantois develops outward from the embryo to establish the al lantochorion, which defines the size of the functional placenta. During implantation, chorionic trophoblasts adhere to endometrial epithelial cells. Placenta...

While the role of oestradiol and progesterone in the control of GnRH pulsatile secretion and generation of the preovulatory GnRH surge to induce release of the LH surge has been fully investigated, less attention has been given to changes in the pituitary gland that may sensitize gonadotrophs to switch from pulsatile release to surge release of LH, in particular. Furthermore, in the follicular phase while pulsatile secretion of LH is maximal, FSH secretion is reduced, yet both...

Abstract unavailable© 2009 Society for Reproduction and Fertility...

Abstract unavailable© 2009 Society for Reproduction and Fertility...

Reduced reproductive efficiency has been reported in high-producing dairy cows. Sources of reproductive inefficiency include decreased expression of estrus, increased diameter of the ovulatory follicle and reduced fertility when cows are inseminated after estrus, increased incidence of double ovulation and twinning, and increased pregnancy loss. To overcome some of these inefficiencies, reproductive management programs have been developed that synchronize ovulation and enable ...

Summary. Reproductive traits can range from lowly to moderately heritable. Genomic technologies provide a powerful tool for improving selection for traits that are lowly heritable, sex-linked, or not expressed until later in life. Therefore, as genomic technologies become a part of selection decisions, there is a critical need to understand how specific gene variants affect reproductive traits in cattle. Both classical quantitative genetics approaches and geno...