Effect of calf death loss on cloned cattle herd derived from somatic cell nuclear transfer: Clones with congenital defects would be removed by the death loss

Abstract

To increase public understanding on cloned cattle derived from somatic cell nuclear transfer (SCNT), the present review describes the effect of calf death loss on an SCNT cattle herd. The incidence of death loss in SCNT cattle surviving more than 200 days reached the same level as that in conventionally bred cattle. This process could be considered as removal of SCNT cattle with congenital defects caused by calf death loss. As a result of comparative studies of SCNT cattle and conventionally bred cattle, the substantial equivalences in animal health status, milk and meat productive performance have been confirmed. Both sexes of SCNT cattle surviving to adulthood were fertile and their reproductive performance, including efficiency of progeny production, was the same as that in conventionally bred cattle. The presence of substantial equivalence between their progeny and conventionally bred cattle also existed. Despite these scientific findings, the commercial use of food products derived from SCNT cattle and their progeny has not been allowed by governments for reasons including the lack of public acceptance of these products and the low efficiency of animal SCNT. To overcome this situation, communication of the low risk of SCNT technology and research to improve SCNT efficiency are required.

Artificial cloning of domestic animals

“…Other work has focused on the health of clones: these studies suggest that clones that survive the critical neonatal period are generally normal physiologically. Cattle clones surviving greater than 200 d were found to be essentially equivalent in terms of animal health and milk and meat production performance as conventionally bred cattle (66). These studies support the feasibility of using clones in various comparative studies.…”

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

“…Steatosis may also have contributed to the nuclear alterations we observed, since lipid vesicles compress the nucleus at the periphery of the hepatocyte, leading to its deformation. A Japanese survey of the necropsy findings relative to clones at various postnatal stages reported hepatic lesions in 14 out of 38 neonatal deaths, whereas this number dropped to two out of 25 at later stages of life27. This survey, together with the present study, both support the idea that pathological clones are characterized by an improper reprogramming of liver functions, which impairs their ability to adapt to postnatal life.…”

“…Episodic losses are still reported up to six months of age, after which the health of clones is compatible with reproduction, lactation and meat production in most animals22232425. To date, adult clones have been considered as being free of major abnomalities26, suggesting a selection of normal individuals through the gradual loss of pathological clones during development27. The large number of abnormalities observed in perinatal clones, and the clinically normal phenotype of adult clones arising from the same donor cells, thus provide an unique opportunity to explore the DNA sequence-independent mechanisms underlying perinatal mortality in cattle.…”

The complex relationship between welfare and reproduction in cattle

“…To the authors’ best knowledge, production of cloned calves through somatic cell nuclear transfer (SCNT) is not currently used commercially as some challenges remain: for example, pregnancy rates and full‐term development rates are relatively low (see Akagi, Geshi, & Nagai, ). Additionally, abnormally high birthweight and congenital defects lead to higher mortality rates, which are clear risks to welfare (see Watanabe, ). Furthermore, there are risks that these advanced reproduction technologies may fail to resonate with societal values given that they may be perceived as unnatural and thus, negatively influence public attitudes towards food animal production (e.g., Pieper, Doherr, & Heuwieser, ).…”