title: In vitro manipulation techniques of porcine embryos: a meta-analysis related to transfers, pregnancies and piglets.
abstract: During the last 17 years, considerable advancements have been achieved in the production of pigs, transgenic and non-transgenic, by methods of somatic cell nuclear transfer, in vitro fertilisation, intracytoplasmic sperm injection, microinjection and sperm-mediated gene transfer by artificial insemination. Therefore, a review of the overall efficiency for the developmental competence of embryos produced by these in vitro methods would be useful in order to obtain a more thorough overview of this growing area with respect to its development and present status. In this review a meta-analysis was used to analyse data collected from all published articles with a focus on zygotes and embryos for transfer, pregnancy, full-term development and piglets born. It was generally concluded that an increasing level of in vitro manipulation of porcine embryos decreased the overall efficiency for production of piglets. The techniques of nuclear transfer have been developed markedly through the increasing number of studies performed, and the results have become more stable. Prolonged in vitro culture period did not lead to any negative effect on nuclear transfer embryos after their transfer and it resulted in a similar or even higher litter size. More complete information is needed in future scientific articles about these in vitro manipulation techniques to establish a more solid basis for the evaluation of their status and to reveal and further investigate any eventual problems.
authors.affiliation: Reproductive Biology, Department of Animal Science, Aarhus University, DK-8830 Tjele, Denmark.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Reproductive Biology, Department of Animal Science, Aarhus University, DK-8830 Tjele, Denmark.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, DK-8830 Tjele, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Løvendahl
authors.affiliation: Department of Large Animal Sciences, Faculty of Life Science, University of Copenhagen, DK-1870 Frederiksberg C, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Schmidt
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, DK-8830 Tjele, Denmark.
authors.forename: Knud
authors.initials: K
authors.lastname: Larsen
authors.affiliation: Reproductive Biology, Department of Animal Science, Aarhus University, DK-8830 Tjele, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Callesen
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D004624:Embryo Transfer / Q000379:methods / Q000662:veterinary*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005307:Fertilization in Vitro / Q000379:methods / Q000662:veterinary*; D008098:Litter Size; D053652:Nuclear Transfer Techniques / Q000662:veterinary*; D011247:Pregnancy; D013552:Swine