Postmortem findings in cloned and transgenic piglets dead before weaning

Area of Science:

• Veterinary Medicine
• Developmental Biology
• Genetics

Background:

• Somatic cell nuclear transfer (SCNT) in pigs is associated with high pre-weaning mortality.
• Gross malformations of vital organs are a primary contributor to this mortality.
• Understanding these malformations is crucial for improving SCNT efficiency and animal welfare.

Purpose of the Study:

• To retrospectively describe the types and prevalence of malformations in cloned piglets (transgenic and non-transgenic).
• To analyze malformation rates across different pig breeds (Large White, Göttingen, Yucatan) and transgenic status.
• To identify specific organ systems most affected by malformations in cloned piglets.

Main Methods:

• Retrospective analysis of cloned piglet data from SCNT procedures.
• Embryo transfer into Large White recipients.
• Data collection on pregnancy rates, abortions, stillbirths, and post-weaning mortality.
• Detailed examination and classification of malformations in born piglets.

Main Results:

• Overall pre-weaning mortality reached 58%, with 21% stillborn and 48% mortality post-birth.
• Malformations were observed in 29.5% of all born piglets, with 7.4% showing multiple defects.
• Transgenic Göttingen and Yucatan piglets exhibited higher malformation rates (32% and 46%) than non-transgenic Large White piglets (17%).
• Digestive, reproductive, circulatory, and musculoskeletal systems were most commonly affected.
• Musculoskeletal defects were highest in Göttingen, while cardiopulmonary defects were most frequent in Yucatan piglets.

Conclusions:

• Pig cloning results in substantial piglet loss, largely due to diverse malformations.
• Many observed malformations are also present in non-cloned piglets.
• Despite challenges, cloned pigs remain viable models for human disease research, provided malformation rates are further reduced.