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Ovulation Statuses of Surrogate Gilts Are Associated with the Efficiency of Excellent Pig Cloning.

Huan Y, Hu K, Xie B, Shi Y, Wang F, Zhou Y, Liu S, Huang B, Zhu J, Liu Z, He Y, Li J, Kong Q, Liu Z - PLoS ONE (2015)

Bottom Line: When estrus stage of surrogate gilts was compared, group of embryo transfer on Day 2 of estrus showed significantly higher pregnancy rate, delivery rate, average number of piglets born, average alive piglet number or cloning efficiency than group on Day 1, Day 3, Day 4 or Day 5, respectively (P<0.05).And, in comparison with the preovulation and postovulation groups, group of surrogate gilts during periovulation displayed a significantly higher overall cloning efficiency (P<0.05).This work would have important implications in preserving and breeding excellent livestock and improving the overall cloning efficiency.

View Article: PubMed Central - PubMed

Affiliation: College of Life Science, Northeast Agricultural University, Harbin, Heilongjiang Province, China.

ABSTRACT
Somatic cell nuclear transfer (SCNT) is an assisted reproductive technique that can produce multiple copies of excellent livestock. However, low cloning efficiency limits the application of SCNT. In this study, we systematically investigated the major influencing factors related to the overall cloning efficiency in pigs. Here, 13620 cloned embryos derived from excellent pigs were transferred into 79 surrogate gilts, and 119 live cloned piglets were eventually generated. During cloning, group of cloned embryos derived from excellent Landrace or Large white pigs presented no significant differences of cleavage and blastocyst rates, blastocyst cell numbers, surrogate pregnancy and delivery rates, average numbers of piglets born and alive and cloning efficiencies, and group of 101-150, 151-200 or 201-250 cloned embryos transferred per surrogate also displayed a similar developmental efficiency. When estrus stage of surrogate gilts was compared, group of embryo transfer on Day 2 of estrus showed significantly higher pregnancy rate, delivery rate, average number of piglets born, average alive piglet number or cloning efficiency than group on Day 1, Day 3, Day 4 or Day 5, respectively (P<0.05). And, in comparison with the preovulation and postovulation groups, group of surrogate gilts during periovulation displayed a significantly higher overall cloning efficiency (P<0.05). Further investigation of surrogate estrus stage and ovulation status displayed that ovulation status was the real factor underlying estrus stage to determine the overall cloning efficiency. And more, follicle puncture for preovulation, not transfer position shallowed for preovulation or deepened for postovulation, significantly improved the average number of piglets alive and cloning efficiency (P<0.05). In conclusion, our results demonstrated that ovulation status of surrogate gilts was the fundamental factor determining the overall cloning efficiency of excellent pigs, and follicle puncture, not transfer position change, improved cloning efficiency. This work would have important implications in preserving and breeding excellent livestock and improving the overall cloning efficiency.

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Ovulation statuses of surrogate gilts when cloned embryos transferred.A, preovulation, follicles large developed but not ovulated; B, periovulation, follicles partly ovulated; and C, postovulation, follicles all ovulated. Surrogate gilts during periovulation were suitable for pig cloning.
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pone.0142549.g003: Ovulation statuses of surrogate gilts when cloned embryos transferred.A, preovulation, follicles large developed but not ovulated; B, periovulation, follicles partly ovulated; and C, postovulation, follicles all ovulated. Surrogate gilts during periovulation were suitable for pig cloning.

Mentions: Generally, ovulation status of surrogates is associated with estrus stage. When cloned embryos were transferred (Fig 2), the Day 1 group, 18 h after estrus, showed 90.00% surrogates under preovulation and 10% periovulation, the Day 2 or Day 3 group (42 h or 66 h after estrus) displayed 40.00% or 11.76% surrogates preovulation, 56.00% or 29.41% periovulation and 4.00% or 58.82% postovulation, respectively, and the Day 4 and Day 5 groups (90 and 114 h after estrus) were all under postovulation, indicating that ovulation status could be a factor related to the overall cloning efficiency. When the effect of ovulation statuses was investigated (Table 4 and Fig 3), significantly higher rates of pregnancy and delivery, numbers of born and live piglets per surrogate and cloning efficiency were observed in the periovulation group compared with the preovulation or postovulation group (P<0.05), and the postovulation group displayed the lowest overall cloning efficiency, suggesting that ovulation status could be also an important factor determining the overall cloning efficiency. Further investigation of the mixed effects of estrus stage and ovulation status displayed that ovulation status was the real factor underlying estrus stage to determine the overall cloning efficiency (Table B in S1 File). And, for surrogates under periovulation in the Day 2 group (Table C in S1 File), both the rates of pregnancy and delivery were 100%, numbers of piglets born and alive per surrogate was 5.00 and 3.50, respectively, and cloning efficiency reached 2.20%. In all, surrogate ovulation status was the fundamentally decisive factor influencing the overall cloning efficiency, and selecting gilts during periovulation as surrogates to transfer cloned embryos can facilitate the synchronization of cloned embryos and surrogates, thereby, resulting in the high overall cloning efficiency.


Ovulation Statuses of Surrogate Gilts Are Associated with the Efficiency of Excellent Pig Cloning.

Huan Y, Hu K, Xie B, Shi Y, Wang F, Zhou Y, Liu S, Huang B, Zhu J, Liu Z, He Y, Li J, Kong Q, Liu Z - PLoS ONE (2015)

Ovulation statuses of surrogate gilts when cloned embryos transferred.A, preovulation, follicles large developed but not ovulated; B, periovulation, follicles partly ovulated; and C, postovulation, follicles all ovulated. Surrogate gilts during periovulation were suitable for pig cloning.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643933&req=5

pone.0142549.g003: Ovulation statuses of surrogate gilts when cloned embryos transferred.A, preovulation, follicles large developed but not ovulated; B, periovulation, follicles partly ovulated; and C, postovulation, follicles all ovulated. Surrogate gilts during periovulation were suitable for pig cloning.
Mentions: Generally, ovulation status of surrogates is associated with estrus stage. When cloned embryos were transferred (Fig 2), the Day 1 group, 18 h after estrus, showed 90.00% surrogates under preovulation and 10% periovulation, the Day 2 or Day 3 group (42 h or 66 h after estrus) displayed 40.00% or 11.76% surrogates preovulation, 56.00% or 29.41% periovulation and 4.00% or 58.82% postovulation, respectively, and the Day 4 and Day 5 groups (90 and 114 h after estrus) were all under postovulation, indicating that ovulation status could be a factor related to the overall cloning efficiency. When the effect of ovulation statuses was investigated (Table 4 and Fig 3), significantly higher rates of pregnancy and delivery, numbers of born and live piglets per surrogate and cloning efficiency were observed in the periovulation group compared with the preovulation or postovulation group (P<0.05), and the postovulation group displayed the lowest overall cloning efficiency, suggesting that ovulation status could be also an important factor determining the overall cloning efficiency. Further investigation of the mixed effects of estrus stage and ovulation status displayed that ovulation status was the real factor underlying estrus stage to determine the overall cloning efficiency (Table B in S1 File). And, for surrogates under periovulation in the Day 2 group (Table C in S1 File), both the rates of pregnancy and delivery were 100%, numbers of piglets born and alive per surrogate was 5.00 and 3.50, respectively, and cloning efficiency reached 2.20%. In all, surrogate ovulation status was the fundamentally decisive factor influencing the overall cloning efficiency, and selecting gilts during periovulation as surrogates to transfer cloned embryos can facilitate the synchronization of cloned embryos and surrogates, thereby, resulting in the high overall cloning efficiency.

Bottom Line: When estrus stage of surrogate gilts was compared, group of embryo transfer on Day 2 of estrus showed significantly higher pregnancy rate, delivery rate, average number of piglets born, average alive piglet number or cloning efficiency than group on Day 1, Day 3, Day 4 or Day 5, respectively (P<0.05).And, in comparison with the preovulation and postovulation groups, group of surrogate gilts during periovulation displayed a significantly higher overall cloning efficiency (P<0.05).This work would have important implications in preserving and breeding excellent livestock and improving the overall cloning efficiency.

View Article: PubMed Central - PubMed

Affiliation: College of Life Science, Northeast Agricultural University, Harbin, Heilongjiang Province, China.

ABSTRACT
Somatic cell nuclear transfer (SCNT) is an assisted reproductive technique that can produce multiple copies of excellent livestock. However, low cloning efficiency limits the application of SCNT. In this study, we systematically investigated the major influencing factors related to the overall cloning efficiency in pigs. Here, 13620 cloned embryos derived from excellent pigs were transferred into 79 surrogate gilts, and 119 live cloned piglets were eventually generated. During cloning, group of cloned embryos derived from excellent Landrace or Large white pigs presented no significant differences of cleavage and blastocyst rates, blastocyst cell numbers, surrogate pregnancy and delivery rates, average numbers of piglets born and alive and cloning efficiencies, and group of 101-150, 151-200 or 201-250 cloned embryos transferred per surrogate also displayed a similar developmental efficiency. When estrus stage of surrogate gilts was compared, group of embryo transfer on Day 2 of estrus showed significantly higher pregnancy rate, delivery rate, average number of piglets born, average alive piglet number or cloning efficiency than group on Day 1, Day 3, Day 4 or Day 5, respectively (P<0.05). And, in comparison with the preovulation and postovulation groups, group of surrogate gilts during periovulation displayed a significantly higher overall cloning efficiency (P<0.05). Further investigation of surrogate estrus stage and ovulation status displayed that ovulation status was the real factor underlying estrus stage to determine the overall cloning efficiency. And more, follicle puncture for preovulation, not transfer position shallowed for preovulation or deepened for postovulation, significantly improved the average number of piglets alive and cloning efficiency (P<0.05). In conclusion, our results demonstrated that ovulation status of surrogate gilts was the fundamental factor determining the overall cloning efficiency of excellent pigs, and follicle puncture, not transfer position change, improved cloning efficiency. This work would have important implications in preserving and breeding excellent livestock and improving the overall cloning efficiency.

Show MeSH
Related in: MedlinePlus