Perinatal Physiology in Cloned And Normal Calves: Physical And Clinical Characteristics

Abstract

The period immediately after birth is a vital time for all newborn calves as the cardiovascular, respiratory, and other organ systems adapt to life ex utero. Reported neonatal mortality rates suggest this period to be especially critical in cloned calves; yet prospective, controlled studies on the physiological status of these calves are lacking. The objectives of this study were to compare neonatal (birth to 48 h of age) physical and clinical characteristics and placental morphology of cloned and embryo transfer control calves delivered by cesarean section after induced labor. All calves were raised under specialized neonatal-care protocols at a large-animal veterinary research and teaching hospital. Cloned calves were similar to controls for many parameters studied. Notable exceptions included developmental delays of important physical adjustment parameters and enlargement of the umbilical region. Placentas associated with cloned calves contained fewer total placentomes, a twofold increase in surface area and mass per placentome, and a shift in placentome morphology toward larger, flatter placentomes. The most striking clinical variations detected in clones were hypoglycemia and hyperfructosemia, both measures of carbohydrate metabolism. Because the placenta is known to be the source of plasma fructose in newborn calves, increased fructose production by the cloned placenta may be an important factor in the etiology of umbilical and cardiac anomalies in clones observed in this and other studies.

Aberrant gene expression patterns in placentomes are associated with phenotypically normal and abnormal cattle cloned by somatic cell nuclear transfer

“…For example, in IVF placentas glucose and fructose levels are higher than in AI placentas, whereas in SCNT placentas lactate and fructose levels are higher than in AI placentas (8,58,70). Recently, it was also shown that neonatal SCNT calves have high fructose levels and low glucose and lactate levels in their blood (3). Glucose, fructose, and lactate serve as energy sources for the placenta and fetus (77), and artificial elevation of lactate levels in the fetal plasma in near-term pregnancies results in polyhydramnios and/or hydrops fetalis (70).…”

Avaliação ultrassonográfica da involução das estruturas umbilicais extra e intracavitárias em bezerros sadios da raça Nelore concebidos naturalmente e produtos de fertilização in vitro

“…Em alguns destes estudos foi observado peso ao nascimento superior em animais concebidos por biotécnicas artificiais (Garry et al 1996, Kruip & den Daas 1997, Jacobsen et al 2000, Batchelder et al 2007, Meirelles et al 2010.…”

“…aliadas ao gigantismo, são bem caracterizadas nos bezerros clonados, assim como o maior tamanho dos vasos umbilicais e a maior incidência de doenças envolvendo essas estruturas (Garry et al 1996, Batchelder et al 2007, Miglino et al 2007, Meirelles et al 2010). Nos produtos de PIVE isso não está bem elucidado.…”

“…Como evidenciado na rotina prática, esses bezerros podem nascer com os vasos umbilicais mais calibrosos, os quais se atrofiam mais lentamente. No caso dos bezerros clonados já está bem caracterizado que nascem com tamanho e peso maiores, com vasos umbilicais de maior diâmetro e apresentam maior chance de desenvolverem doenças umbilicais (Garry et al 1996, Batchelder et al 2007, Miglino et al 2007, Meirelles et al 2010. A ocorrência da síndrome do bezerro grande (Large Offspring Syndrome) é comumente descrita em animais frutos de processos artificiais de fertilização e não somente nos bezerros clonados (Behboodi et al 1995, Kruip & den Daas 1997, Young et al 1998, Jacobsen et al 2000, Bertolini & Anderson 2002, Farin et al 2006.…”

Altered DNA methylation associated with an abnormal liver phenotype in a cattle model with a high incidence of perinatal pathologies

“…As well as the constant developmental waste observed after implantation in cloned pregnancies16, the perinatal period is marked by important foetal and neonatal losses171819. Foetal growth peaks towards the end of pregnancy and makes considerable demands on the maternal nutrient supply.…”