For the ex-situ conservation of giant pandas, both collecting and preserving semen are important methods. The seminal plasma is rich in nutrients and bioactive substances, such as proteins, carbohydrates, lipids, amino acids, and hormones, which play an important role in the reproduction and reproductive health of the species. This is the first study to analyze the seminal plasma proteins of giant pandas through proteomics and identified 1125 proteins. These proteins are related to protein turnover, translation, and metabolism. The seminal plasma proteins of giant pandas were then compared to those of humans, pigs and sheep, with many unique proteins found in giant panda samples. Among these proteins, the WD40 repeat-containing proteins have been identified and implicated in sperm function and fertility. Understanding the composition and function of proteins in the giant panda seminal plasma proteome can provide valuable insights into their reproductive biology and help develop strategies to improve their reproductive success in captivity, which is essential for giant panda conservation.

To contribute to the conservation of endangered animals, the utilization of model systems is critical to analyze the function of their gut microbiota. In this study, the results of a fecal microbial transplantation (FMT) experiment with germ-free (GF) mice receiving giant panda or horse fecal microbiota showed a clear clustering by donor microbial communities in GF mice, which was consistent with the results of blood metabolites from these mice. At the genus level, FMT re-established approximately 9% of the giant panda donor microbiota in GF mice compared to about 32% for the horse donor microbiota. In line with this, the difference between the panda donor microbiota and panda-mice microbiota on whole-community level was significantly larger than that between the horse donor microbiota and the horse-mice microbiota. These results were consistent with source tracking analysis that found a significantly higher retention rate of the horse donor microbiota (30.9%) than the giant panda donor microbiota (4.0%) in GF mice where the microbiota remained stable after FMT. Further analyses indicated that the possible reason for the low retention rate of the panda donor microbiota in GF mice was a low relative abundance of Clostridiaceae in the panda donor microbiota. Our results indicate that the donor microbiota has a large effect on GF mice microbiota after FMT.

Different responses of gut microbiota diversity affect host health in term of nutrient metabolism and disease immunity, the reason and the impact of low diversity level of giant panda needs to be studied. Therefore, to explore the impact of intestinal type and diet on gut microbiota diversity of giant pandas, we conducted a multi-species comparison (n=73), and the effects of different diets on gut microbiota function of giant panda were analyzed by PICRUSt method. The gut microbiota of giant panda was significantly lower than the same diets type herbivores and the same intestinal type carnivores. High-fiber bamboo culm diet significantly reduced the gut microbiota diversity of giant panda than bamboo shoot and leaf. The low diversity of gut microbiota led to the low nutritional metabolic function of giant panda, including energy metabolism and amino acid metabolism. These results showed that the short intestinal tract and high fiber diet caused the decrease of gut microbiota diversity of giant pandas.