title: Influence of embryo handling and transfer method on pig cloning efficiency.
abstract: The somatic cell nuclear transfer (SCNT) technique could be used to produce genetically superior or genetically engineered cloned pigs that have wide application in agriculture and bioscience research. However, the efficiency of porcine SCNT currently is very low. Embryo transfer (ET) is a key step for the success of SCNT. In this study, the effects of several ET-related factors, including cloned embryo culture time, recipient's ovulation status, co-transferred helper embryos and ET position, on the success rate of pig cloning were investigated. The results indicated that transfer of cloned embryos cultured for a longer time (22-24h vs. 4-6h) into pre-ovulatory sows decreased recipient's pregnancy rate and farrowing rate, and use of pre-ovulatory and post-ovulatory sows as recipients for SCNT embryos cultured for 22-24h resulted in a similar porcine SCNT efficiency. Use of insemination-produced in vivo fertilized, parthenogenetically activated and in vitro fertilized embryos as helper embryos to establish and/or maintain pregnancy of SCNT embryos recipients could not improve the success rate of porcine SCNT. Transfer of cloned embryos into double oviducts of surrogates significantly increased pregnancy rate as well as farrowing rate of recipients, and the developmental rate of transferred cloned embryos, as compared to unilateral oviduct transfer. This study provided useful information for optimization of the embryo handling and transfer protocol, which will help to improve the ability to generate cloned pigs.
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China.
authors: Junsong
authors: J
authors: Shi
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China.
authors: Rong
authors: R
authors: Zhou
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China.
authors: Lvhua
authors: L
authors: Luo
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China.
authors: Ranbiao
authors: R
authors: Mai
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China.
authors: Haiyu
authors: H
authors: Zeng
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China; College of Animal Science, South China Agricultural University, Guangdong, PR China.
authors: Xiaoyan
authors: X
authors: He
authors: College of Animal Science, South China Agricultural University, Guangdong, PR China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangdong, PR China.
authors: Dewu
authors: D
authors: Liu
authors: College of Animal Science, South China Agricultural University, Guangdong, PR China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangdong, PR China.
authors: Fang
authors: F
authors: Zeng
authors: College of Animal Science, South China Agricultural University, Guangdong, PR China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangdong, PR China.
authors: Gengyuan
authors: G
authors: Cai
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China.
authors: Hongmei
authors: H
authors: Ji
authors: College of Animal Science, South China Agricultural University, Guangdong, PR China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangdong, PR China.
authors: Fei
authors: F
authors: Tang
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China.
authors: Qinglai
authors: Q
authors: Wang
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China; College of Animal Science, South China Agricultural University, Guangdong, PR China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangdong, PR China. Electronic address: wzfemail@163.com.
authors: Zhenfang
authors: Z
authors: Wu
authors: National Engineering Research Center for Breeding Swine Industry, South China Agricultural University and Guangdong Wen's Foodstuff Group, Guangdong, PR China; College of Animal Science, South China Agricultural University, Guangdong, PR China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangdong, PR China. Electronic address: lizicong@scau.edu.cn.
authors: Zicong
authors: Z
authors: Li
mesh_terms: D000818:Animals; D019976:Cloning, Organism / Q000379:methods / Q000662:veterinary*; D046149:Embryo Culture Techniques / Q000662:veterinary; D004624:Embryo Transfer / Q000379:methods / Q000662:veterinary*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary; D010312:Parthenogenesis; D011247:Pregnancy; D013552:Swine / Q000196:embryology* / Q000502:physiology*
keywords: Cloned pigs; Embryo transfer; SCNT