title: In vitro ovine embryo production: the study of seasonal and oocyte recovery method effects.
abstract: BACKGROUND
  To current knowledge, different oocyte's recovery method and various seasons have profound impact on in vitro embryo production (IVEP).
  
  
  OBJECTIVE
  The aim of this study was to define an efficient recovery method for oocytes harvesting from slaughterhouse material in different seasons, and their effects on IVEP yield.
  
  
  METHODS
  Ovaries from slaughtered ewes in breeding season (BS) and non-breeding season (NBS) were collected from a local abattoir. The oocytes were recovered through aspiration, centrifugation (ORC), puncture and slicing, and categorized into three classes (I, oocytes with more than three layers of cumulus cells; II, less than three layers with damaged cumulus cells; III, denuded oocytes). After cultivation in TCM 199 for 24 hours, matured oocytes were subjected to in vitro fertilization (IVF) and in vitro culture (IVC). The oocyte recovery using ORC in BS and NBS was significantly higher (P < 0.05) compared with other recovery methods.
  
  
  RESULTS
  No significant dissimilarities in the proportion of oocytes reaching M-II stage were recorded when using different oocyte recovery methods in different seasons. Aspiration resulted in lower (P < 0.05) proportion of class I (BS, 60.0 ± 2.1; NBS, 51.1 ± 2.1) compared to ORC (BS, 82.0 ± 1.2; NBS, 70.0 ± 1.2), slicing (BS, 80.0 ± 2.1; NBS, 71.0 ± 1.4) and puncture (BS, 80.0 ± 1.5; NBS, 72.0 ± 2.0). Monospermy and blastocyst development rates were significantly higher using ORC than other recovery techniques in both BS and NBS. More oocytes with high quality, greater blastocyst development and oocyte recovery rates were achieved in BS.
  
  
  CONCLUSIONS
  The results revealed that oocytes harvesting technique and season are effective in the rate of cleavage and blastocysts' development, and suggest that despite same meiotic resumption rate in all treatments, it would be better to use ORC.
authors.affiliation: Department of Animal Science, Faculty College of Agriculture and Natural Resources, University of Tehran, Karaj, IR Iran.
authors.forename: Navid
authors.initials: N
authors.lastname: Dadashpour Davachi
authors.affiliation: Department of Animal Science, Faculty College of Agriculture and Natural Resources, University of Tehran, Karaj, IR Iran.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Zare Shahneh
authors.affiliation: Department of Animal Science, Faculty College of Agriculture and Natural Resources, University of Tehran, Karaj, IR Iran ; Department of Clinical Sciences, Faculty of Veterinary Medicine, Shahid Chamran University, Ahvaz, IR Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Kohram
authors.affiliation: Department of Animal Science, Faculty College of Agriculture and Natural Resources, University of Tehran, Karaj, IR Iran.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Zhandi
authors.affiliation: Department of Animal Science, Faculty College of Agriculture and Natural Resources, University of Tehran, Karaj, IR Iran.
authors.forename: Saeed
authors.initials: S
authors.lastname: Dashti
authors.affiliation: Department of Animal Science, Faculty College of Agriculture and Natural Resources, University of Tehran, Karaj, IR Iran.
authors.forename: Helia
authors.initials: H
authors.lastname: Shamsi
authors.affiliation: Kowsar Corporation, Tehran, IR Iran.
authors.forename: Razieh
authors.initials: R
authors.lastname: Moghadam
keywords: Embryo Production; Fertilization in Vitro; In Vitro Oocyte Maturation Techniques; Oocytes; Sheep