Prospective study on the excretion of mucous stools and its association with age, gender, and feces output in captive giant pandas

The giant panda (Ailuropoda melanoleuca) has evolved a large number of mucous glands in the intestinal lining to adapt to the digestion of high-fiber foods. However, in captive pandas, excessive mucus might form a mass and then be eliminated, which is often accompanied by discomfort and decreased activity. This event is called ‘mucous excretion’. The causes of mucus excretions in captive pandas, however, remain unknown. The aims of this study were to document the occurrence of mucus excretion and to investigate its possible associations with pandas’ age, gender, and feces output. Eighteen giant pandas were studied at the Beijing Zoo from April 2003 to June 2017, and a total of 900 occurrences of mucous excretion and 32,856 daily defecation outputs in weight were recorded. The likelihood of mucous excretion occurrence decreased by 11.34% for each 1 kg of fecal output (Z = −4.12, p < 0.0001), while it increased by 5.89% per year of age (Z = 4.02, p < 0.0001). However, individual differences in gender had no significant effect on the mucous occurrence (Z = −0.75, p = 0.4508). A monthly change in mucus occurrence was also found. The mean frequency of mucus occurrence was significantly higher in October. In August, time (month) change showed the biggest negative influence on feces output but the biggest positive influence on mucus excretion (seasonal factors were −2.261 and 0.0126, respectively). Our results documented the occurrence of mucous excretions and confirmed their possible associations with the pandas’ age and fecal output based on a 15-year prospective study. This study not only adds to our knowledge of panda physiology but also suggests the need for further studies examining the causes of the excretion of mucous stools in captive pandas. Reducing the incidence of mucous excretion would promote ex situ conservation and enhance panda welfare.