| Autor: |
Smith, B. D., Poliakiwski, B., Polanco, O., Singleton, S., de Melo, G. D., Muntari, M., Oliveira Filho, R. V., Pohler, K. G. |
| Předmět: |
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| Zdroj: |
Reproduction, Fertility & Development; 2023, Vol. 35 Issue 1/2, p70-83, 14p |
| Abstrakt: |
Beef cattle producers rely on each of their cows to produce a marketable calf each year to maintain a sustainable operation. Within the first month of gestation, pregnancy failures have been recorded to be upwards of 40–50%. From fertilisation to birth, there are numerous factors contributing to pregnancy failure. From the beginning of gestation oocyte competence is often a large factor impacting fertility as the dam contributes all mRNA for initial embryo development. Other factors contributing to early embryonic infertility include hormonal concentration and heat stress. After the embryo enters the uterus, it becomes critical for the uterus to be receptive to the developing conceptus. The embryo then begins to elongate and secrete interferon-tau to initiate maternal recognition of pregnancy; a requirement to establish and maintain bovine pregnancies. After a pregnancy completes these steps, placentation actively begins around day 22 of pregnancy and lasts until organogenesis. The fetal phase follows the embryonic phase where disease and/or toxins are often the cause of pregnancy failure at this period. However, fetal mortality has been reported to occur in less than 10% of pregnancies. Understanding of the many factors influencing infertility needs to be further investigated to increase pregnancy success in beef cattle. Pregnancy failure has been reported to occur in all species, and the lowered fertility associated with these failures has previously appeared to be a never ending battle. Pregnancy losses in beef cattle are of special interest to the authors as the global economic loss has been found to be greater than US$1 billion each year. Better temporal understanding of beef cattle pregnancy failures could allow for the better inclusion of animal models studying the improval of human reproduction medicine. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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