Embryo mortality and its prevention

1995 ◽  
Vol 1995 ◽  
pp. 8-8
Author(s):  
A R Peters
Keyword(s):  
Dairy Cows ◽  
Corpus Luteum ◽  
Early Pregnancy ◽  
Cycle Length ◽  
Ovarian Follicle ◽  
Biological Significance ◽  
Prostaglandin E ◽  
Embryo Mortality ◽  
Embryonic Loss ◽  
Theca Interna

The economic and biological significance of embryo mortality in cattle is well recognised. About 90% or more ova are fertilised at oestrus but only about 55% of dairy cows calve to first insemination (reviewed by Sreenan and Diskin, 1985). Of this 35% post fertilisation loss, most (25-30%) occurs within a cycle length therefore not affecting the time of return to the subsequent oestrus. It is also accepted that the maintenance of early pregnancy requires the secretion of progesterone by a viable corpus luteum and that premature luteolysis is the major cause of embryonic loss during these early days of pregnancy.The corpus luteum forms after ovulation from the cells of the granulosa and theca interna layers of the ovarian follicle. These are thought to differentiate into the large and small luteal cells respectively (Smith et al., 1994). The large cells secrete progesterone and oxytocin and are responsive to prostaglandin E whilst the small ones secrete progesterone and are responsive to LH (reviewed by Wiltbank, 1994).

Embryo mortality and its prevention

1995 ◽  
Vol 1995 ◽  
pp. 8-8
Author(s):  
A R Peters
Keyword(s):  
Dairy Cows ◽  
Corpus Luteum ◽  
Early Pregnancy ◽  
Cycle Length ◽  
Ovarian Follicle ◽  
Biological Significance ◽  
Prostaglandin E ◽  
Embryo Mortality ◽  
Embryonic Loss ◽  
Theca Interna

The economic and biological significance of embryo mortality in cattle is well recognised. About 90% or more ova are fertilised at oestrus but only about 55% of dairy cows calve to first insemination (reviewed by Sreenan and Diskin, 1985). Of this 35% post fertilisation loss, most (25-30%) occurs within a cycle length therefore not affecting the time of return to the subsequent oestrus. It is also accepted that the maintenance of early pregnancy requires the secretion of progesterone by a viable corpus luteum and that premature luteolysis is the major cause of embryonic loss during these early days of pregnancy.The corpus luteum forms after ovulation from the cells of the granulosa and theca interna layers of the ovarian follicle. These are thought to differentiate into the large and small luteal cells respectively (Smith et al., 1994). The large cells secrete progesterone and oxytocin and are responsive to prostaglandin E whilst the small ones secrete progesterone and are responsive to LH (reviewed by Wiltbank, 1994).

scholarly journals Embryo Mortality Around the Period of Maintenance of the Corpus Luteum Causes Alterations to the Ovarian Function of Lactating Dairy Cows

2016 ◽  
Vol 95 (5) ◽  
pp. 112-112 ◽  
Author(s):  
R. Wijma ◽  
M. L. Stangaferro ◽  
M. M. Kamat ◽  
S. Vasudevan ◽  
T. L. Ott ◽  
...  
Keyword(s):  
Dairy Cows ◽  
Corpus Luteum ◽  
Ovarian Function ◽  
Embryo Mortality ◽  
Lactating Dairy Cows

scholarly journals Recent Possibilities for the Diagnosis of Early Pregnancy and Embryonic Mortality in Dairy Cows

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1666
Author(s):  
Ottó Szenci
Keyword(s):  
Blood Flow ◽  
Dairy Cows ◽  
Early Pregnancy ◽  
Fetal Mortality ◽  
Reproductive Efficiency ◽  
Interferon Tau ◽  
Early Pregnancy Factor ◽  
Pelvic Inlet ◽  
On Farm ◽  
Protein Assays

One of the most recent techniques for the on-farm diagnosis of early pregnancy (EP) in cattle is B-mode ultrasonography. Under field conditions, acceptable results may be achieved with ultrasonography from Days 25 to 30 post-AI. The reliability of the test greatly depends on the frequency of the transducer used, the skill of the examiner, the criterion used for a positive pregnancy diagnosis (PD), and the position of the uterus in the pelvic inlet. Non-pregnant animals can be selected accurately by evaluating blood flow in the corpus luteum around Day 20 after AI, meaning we can substantially improve the reproductive efficiency of our herd. Pregnancy protein assays (PSPB, PAG-1, and PSP60 RIA, commercial ELISA or rapid visual ELISA tests) may provide an alternative method to ultrasonography for determining early pregnancy or late embryonic/early fetal mortality (LEM/EFM) in dairy cows. Although the early pregnancy factor is the earliest specific indicator of fertilization, at present, its detection is entirely dependent on the use of the rosette inhibition test; therefore, its use in the field needs further developments. Recently found biomarkers like interferon-tau stimulated genes or microRNAs may help us diagnose early pregnancy in dairy cows; however, these tests need further developments before their general use in the farms becomes possible.

Corpus luteum blood flow in abnormal early pregnancy.

1996 ◽  
Vol 15 (9) ◽  
pp. 645-649 ◽  
Author(s):  
J L Alcázar ◽  
C Laparte ◽  
G López-Garcia
Keyword(s):  
Blood Flow ◽  
Corpus Luteum ◽  
Early Pregnancy

Memoirs: The Structure of the Ovary and the Formation of the Corpus Luteum in Hoplodactylus Maculatus, Gray

1940 ◽  
Vol s2-82 (326) ◽  
pp. 337-374
Author(s):  
MARY M. M. BOYD
Keyword(s):  
Corpus Luteum ◽  
Zona Pellucida ◽  
Single Layer ◽  
Small Cells ◽  
Follicular Epithelium ◽  
Male And Female ◽  
Physiological Importance ◽  
Egg Membrane ◽  
Theca Externa ◽  
Theca Interna

The structure of the ovary, including stages in the ripening of the oocytes, is described. A prolonged diplotene stage with ‘lamp-brush’ chromosomes is shown to occur in reptiles, as in other classes of vertebrates with large yolky eggs. The striated layer of the egg membrane is shown to be composed of the same cuticular substance as the zona pellucida. A follicular epithelium composed of three types of cells, later reduced to a single layer of small cells, agreeing with Loyez's observations, is described. A discontinuous theca interna, comparable with that of mammalia, is noted outside the membrana propria of the nearly ripe oocyte. A thin, soft, fibrous shell membrane is formed round the uterine egg and polyspermy occurs. The latebra, and the male and female pronuclei in apposition, are described. The corpus luteum is shown to consist of luteal cells invested by fibroblasts from the theca externa. Septa of fibroblasts are also present, but no blood-vessels. The theca is rich in capillaries. The theca interna plays no part in the development of the corpus luteum. A lipoid secretion, which may be of physiological importance, is formed in it. It is compared with that in Monotremes and Marsupials.

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