Dynamic Changes in the Crop Milk and Salivary Microbiota of Breeding Pigeons During the Raising Brooding Period

The microbiota within crop milk not only participates in the physiological regulation of parent pigeons but also promotes the healthy growth of squabs. Consequently, microbial sequencing of both crop milk and the saliva through which it passes is essential to elucidate microbial changes in both compartments during the raising brooding period. This study sampled crop milk and saliva of Mimas at three distinct time points corresponding to Days 1, 4, and 7 of raising brooding, and collected samples from three pairs of healthy breeding pigeons with similar body weights at each time point. The results demonstrated that α diversity increased in both the crop milk and salivary microbiota over time, surpassing the levels observed at the initial secretion stage. Compared to R1, the Simpson index of the salivary microbiome was significantly higher at R7 (p < 0.05). Ligilactobacillus constituted the most abundant genus in crop milk, whereas saliva harbored a greater diversity of potentially pathogenic bacteria. Phylogenetic analysis revealed a close evolutionary relationship between Ligilactobacillus and Enterococcus in crop milk, suggesting potential functional synergy. Furthermore, functional prediction indicated that ABC transporter-related genes presented the lowest expression in the crop milk microbiota during its peak secretion period. Notably, Pearson correlation analysis revealed a significant negative correlation between Ligilactobacillus abundance in crop milk and Psittacicella abundance in saliva. In summary, the crop milk and salivary microbiota exhibit distinct temporal dynamics, and their specific microbial compositions and functions can provide new research directions for the healthy breeding of squabs.