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Efficient one-step direct transfer to recipients of thawed bovine embryos cultured in vitro and frozen in chemically defined medium
Efficient one-step direct transfer to recipients of thawed bovine embryos cultured in vitro and frozen in chemically defined medium
- Source :
- Theriogenology. 146:39-47
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- Direct transfer (DT) of cryopreserved embryos to recipients facilitates on-farm application. We analyzed a new freezing/thawing (F/T) procedure for in vitro produced (IVP) embryos, integrating: 1) an ethylene-glycol based system; 2) a culture step without protein; and 3) a synthetic protein substitute (CRYO3) in cryopreservation medium. IVP embryos from abattoir ovaries were cultured in groups in BSA-containing synthetic oviduct fluid with or without 0.1% fetal calf serum (FCS) until Day-6. Morulae and early blastocysts were subsequently cultured without protein from Day-6 onwards. Day 7 and Day 8 expanded blastocysts (EXB) were subjected to F/T or vitrification/warming (V/W). Thawed and warmed EXB were cultured in vitro, and development rates, cell counts and dead cells were analyzed in surviving embryos. V/W improved survival over F/T (live and hatching rates at 2 h, 24 h and 48 h) (P 0.0001), and FCS before Day 6 did not affect in vitro survival. After F/T, embryos had lower cell counts in the ICM, TE and total cells than after V/W. Day-7 embryos after F/T showed % apoptotic, % pycnotic and % total dead cells higher (p 0.05) than their Day-8 counterparts, probably because F/T reduced the numbers of ICM cells within Day-8 embryos. Thereafter, Day-7 blastocysts were transferred to heifers in an experimental herd. There were no differences in birth rates with frozen (-FCS [n = 40]: 45%; +FCS [n = 14]: 28%), vitrified (-FCS [n = 47]: 53%; +FCS [n = 11]: 36%) and fresh (-FCS [n = 30]: 47%; +FCS [n = 17]: 53%) embryos. However, frozen embryos produced with FCS showed 5/9 miscarriages after Day-40. Calves born from frozen (n = 22), vitrified (n = 29) and fresh (n = 22) transfers did not differ in birth weight, gestation length and daily gain weight (P 0.10). Subsequently, transfer of frozen embryos (n = 29) derived from oocytes collected from live, hormonally stimulated cows in experimental herd, led to pregnancy rates of 57% (heifers) and 40% (dry cows). with EXB on Day-62 Finally, embryos produced with BSA were transferred to cows in an on-field trial (frozen [n = 80]; fresh [n = 58]), with no differences in pregnancy rates (days 30-40). Pregnancy and birth rates could not be predicted from in vitro approaches. The new F/T system yields pregnancy and birth rates comparable to vitrified and fresh embryos without birth overweight. The absence of products of animal origin, defined chemical composition, and direct transfer entail sanitary, manufacturing and application advantages.
- Subjects :
- Fertilization in Vitro
Cryopreservation
Embryo Culture Techniques
Andrology
03 medical and health sciences
Cryoprotective Agents
0302 clinical medicine
Food Animals
Embryo cryopreservation
Pregnancy
Freezing
medicine
Animals
Small Animals
Fetus
030219 obstetrics & reproductive medicine
Equine
Hatching
Chemistry
0402 animal and dairy science
Embryo
04 agricultural and veterinary sciences
Embryo Transfer
Embryo, Mammalian
medicine.disease
Vitrification
040201 dairy & animal science
Culture Media
Chemically defined medium
embryonic structures
Oviduct
Cattle
Female
Animal Science and Zoology
Tissue Preservation
Subjects
Details
- ISSN :
- 0093691X
- Volume :
- 146
- Database :
- OpenAIRE
- Journal :
- Theriogenology
- Accession number :
- edsair.doi.dedup.....cd382628d2821a85575eaa5c74efaade
- Full Text :
- https://doi.org/10.1016/j.theriogenology.2020.01.056