Age-Associated Differences and Rearing Strategy-Related Alterations in the Gut Microbiome of Captive African...

The gut microbiome is critical for the health and dietary adaptation of African elephants (Loxodonta africana), but how age and rearing strategies influence microbial communities remains unclear. Understanding these factors is essential for improving conservation and captive management practices, particularly given the high mortality rates in formula-fed calves. Using 16S rRNA sequencing and clinical data from 17 African elephants (calves: breastfed n = 3, formula-fed n = 2; adults n = 12), we investigated age-associated differences in gut microbiome composition and explored the potential relationship with rearing practices. Due to the limited sample size, results from formula-fed calves were analyzed as exploratory. Healthy adults were dominated by Bacteroidota, a phylum linked to fiber digestion, and showed higher microbial diversity compared to breastfed calves. Exploratory analysis of formula-fed calves revealed distinct compositional features, including reduced Bacteroidota and Lachnospiraceae and enrichment of Gammaproteobacteria, which co-occurred with clinical signs of diarrhea, growth failure. This study highlights age-associated differences in the gut microbiome of healthy African elephants and suggests that formula-feeding may be associated with altered microbial composition. These findings provide a foundation for future research to optimize rearing protocols for captive elephant calves.