Effects of probiotic formulations on GIT morphological changes and gut microbiota in Hu lambs

Gut microbiota plays an important role in the digestive system of ruminants. It affects the health status of Hu sheep and their development and production rates. However, its composition may be influenced by several factors such as gender, age, and diet. In the animal husbandry industry, probiotic formulations have been widely used as alternatives to antibiotics, offering advantages such as non-toxicity, non-residue, and non-pathogenicity. This study aimed to investigate the morphological changes in the gastrointestinal tract and dynamics of gut microbiota during postnatal development of Hu lambs, and evaluated the effects of dietary supplementation with probiotic formulations on gut microbiota. Fifteen male Hu lambs were randomly divided into five groups, with three lambs per group. One blank control group did not receive food postnatally, while two control groups were fed according to standard farm practices with milk and a basic diet. Two experimental groups were administered 10 mL of probiotic formulations within 2 hours after birth, followed by the same feeding regimen as the controls. During the 60-day experiment, samples were collected from the rumen, duodenum, jejunum, and ileum at 2 hours, 20 days, and 55 days after birth. The collected samples included digestive tract tissues and their contents. High-throughput 16S rRNA gene sequencing was employed to identify and analyze microbial diversity, and morphological analysis was conducted to compare differences in the surface tissues of the digestive tract. The results indicated that, with increasing age, the length of the rumen papillae and the height of the villi in the jejunum and ileum of both control and experimental groups continued to increase. Additionally, the overall diversity of the gut microbiota exhibited a gradual upward trend. The microbial diversity indices in the rumen, duodenum, jejunum, and ileum of the experimental group were higher than those of the control group at corresponding time points, although the differences were not statistically significant ( p  > 0.05). The number of beneficial bacteria, such as Ruminococci , in the gastrointestinal tract of Hu lambs in the experimental group increased, while the number of potentially pathogenic bacteria, such as Escherichia spp ., relatively decreased. The results suggest that the supplementation of probiotic formulations promotes early gastrointestinal tract development, enhances the colonization of beneficial bacteria, and improves microbial diversity in Hu lambs. This result provides valuable insights into the gastrointestinal development and microbial dynamics of Hu lambs, as well as the production of probiotic formulations for sheep.