Preovulatory, postovulatory, and postmaternal recognition effects of concentrations of progesterone on embryonic survival in the cow1,2

Abstract

Although fertilization rate usually is very high when male fertility is normal, pregnancy rates are below expectations when defined by the birth of live offspring in response to first service. Factors that affect establishment and retention of pregnancy include 1) preovulatory influences on the follicle and oocyte, 2) early postovulatory uterine and luteal function, 3) concentrations of hormones associated with trophoblastic and endometrial function during maternal recognition of pregnancy, and 4) less-well understood factors during the peri-attachment period. For example, decreased progesterone during preovulatory follicular development leads to a persistent follicle, premature resumption of meiosis, and a high incidence of embryonic death between the 2- and 16-cell stages. Elevated PGF(2alpha) during d 4 to 9 of the estrous cycle not only caused luteolysis but also had a direct embryotoxic effect during the morula-to-blastocyst transition. Ideal conditions during placentation and attachment are not clearly defined. Late embryonic mortality might be increased after ovulation of persistent or immature follicles. Nominal increases in secretion of PGF(2alpha) between d 30 and 35 might be important for attachment and placentation. Lower survival of embryos from wk 5 to wk 7 to 9 of gestation in the cow was associated with lower circulating concentrations of progesterone on wk 5. To maximize embryonic survival in the cow, management must provide high progesterone before estrus, quality detection of estrus, and timely insemination. Luteolytic influences of estradiol-17beta or PGF(2alpha) must be minimized early after mating and during maternal recognition of pregnancy, and high progesterone is needed during the late embryonic/early fetal period.

Effects of restricted feeding on fetal and placental development in pregnant rabbits

“…In the present study, in the subgroup showing serum progesterone concentrations less than 4.0 ng/ml, the embryofetal death index showed a tendency to increase compared with the other subgroup showing serum progesterone concentrations higher than 4.0 ng/ml. In this connection, it is said that a higher serum progesterone concentration is necessary during the above-mentioned period for maintaining embryo-fetal development (Inskeep, 2004). On the other hand, an increase in resorbed embryos that died at the early stage after implantation was considered not to be related to the level of blood progesterone concentration as previously reported in pregnant rabbits subjected to restricted feeding from GD 6 to GD 18 (Clark et al, 1986;Matsuoka et al, 2006).…”

Paradoxical effect of supplementary progesterone between Day 3 and Day 7 on corpus luteum function and conceptus development in cattle

“…may be attributable to inadequate circulating P4 concentrations and the subsequent downstream consequences for endometrial gene expression and histotroph secretion into the uterine lumen (Inskeep 2004;Diskin and Morris 2008).…”

Effects of eCG in Milking Dairy Cows with High Levels of BUN and Synchronized with Ovsynch Protocol

“…Increased uterine luminal PGF2a interferes with embryonic development and survival in dairy cows. High concentrations of circulating P4 in the immediate post-conception period have been associated with an advancement of conceptus elongation, and is associated with increase in interferon-t production 27,35,36,54 . Higher plasma P4 levels ameliorate some of the adverse effects of BUN on fertility after AI in dairy cows 11 .…”