Pigs have been considered as a valuable animal model because of their genetic homology and immunological, anatomical, and physiological similarities with humans [1,2]. Because of these characteristics, they are mainly used in various biomedical research fields. However, their rapid growth rate and large size represent challenges in their use in specific studies, such as xenotransplantation [3,4]. To address these issues, various miniature pig breeds, such as Yucatan, Hanfrod, and Göttingen pigs, have been developed and are increasingly used as model animals for experiments [5,6].

The Yucatan miniature pig (YMP), which originated from the Yucatan Peninsula of Mexico, was established as an experimental animal at Colorado State University [7,8]. Their most significant advantages over domestic pigs (DPs) pertain to their growth rate, adult body weight, and size, which render them well suited for biomedical research [9]. These characteristics have led to their application in various studies, including those on ethology [4] and toxicology [10]. Using gene editing technology, transgenic YMPs are used in xenotransplantation via the ablation of xeno-reactive antigen-related genes [11] the expression of immunological regulatory-related human genes [12,13]; as well as in studies of human disease, such as hypercholesterolemia, via the targeted disruption of lipid-metabolism-related genes [14]. Although various methods are available for producing transgenic pigs, somatic cell nuclear transfer (SCNT) is the most widely adopted approach, which allows the production of transgenic pigs with consistent genotypes, thus minimizing the occurrence of mosaicism [15].

After the successful production of the first cloned pigs using SCNT in 2000 [16], various other types of transgenic pigs have been produced. However, the low production efficiency remains a significant challenge that warrants resolution [17,18]. Previous experiments have mainly used female DPs as surrogate mothers for the production of cloned pigs, including YMPs [19]. Previous studies have reported that the pregnancy and delivery rates in surrogate mothers can be affected by factors such as the ovulation status [20], the duration of in vitro culture (IVC) [21]. A subsequent study showed that the number of piglets produced is affected by the number of SCNT embryos that are transferred [22]. In addition, a previous study reported that the delivery rates were higher when using miniature pigs as surrogate mothers for the production of cloned miniature pigs compared with DPs [23]. As mentioned previously, the production of cloned pigs is affected by various factors, and YMPs probably represent a better surrogate mother vs. DPs. However, the detailed efficiency of the cloning of transgenic YMPs according to various factors and using different recipient breeds has not been examined. Here, we used YMPs and DPs as surrogate mothers for SCNT embryo transfer under various conditions and statistically analyzed results to evaluate production efficiency from multiple perspectives.