Effects of Compound Microecological Preparation Supplementation on Production Performance and Nutrient Apparent Digestibility in Hu Sheep from the Rumen Perspective

Abstract

This study evaluates the effects of a compound microecological preparation named ATABG, which is composed of antimicrobial peptide ID13 and Saccharomyces boulardii, on Hu sheep's growth performance, feed digestibility, and rumen parameters. A total of 40 three-month-old Hu sheep (21.65 ± 0.33 kg) were randomly assigned to two groups: the control group (Con), which received a basal diet, and the experimental group (ATABG), which received the same diet supplemented with 1 g/kg ATABG on a dry matter basis. After a 10-day pre-feeding period to adapt the animals to the experimental diet, dry matter intake and weight gain were recorded during the subsequent 63-day trial period. Body weight was measured on days 1, 21, 42, and 63 of the trial, and animals were slaughtered on day 63 to collect rumen fluid and tissue. Results indicated that ATABG supplementation significantly increased the apparent digestibility of crude protein, neutral detergent fiber, acid detergent fiber, and organic matter (p < 0.05). Rumen fluid analysis revealed increased microbial protein concentration and cellulase activity (p < 0.05) in the ATABG group. Microbiota analysis indicated that ATABG increased the relative abundance of Ruminococcus and Proteobacteria, elevated Firmicutes, and reduced Bacteroidota (p < 0.05). Correlation analysis showed Ruminococcus was positively associated with crude protein digestibility, while Quinella correlated with growth-related indices (r > 0.4, p < 0.05). In conclusion, ATABG supplementation improves protein digestibility and rumen microbial protein synthesis by enriching Ruminococcus and enhancing cellulase activity, potentially optimizing nitrogen utilization in Hu sheep.

Keywords: Ruminococcus; Saccharomyces boulardii; antimicrobial peptides; enzyme activity; rumen microorganisms.

Figure 1

Schematic diagram of the experimental process.

Figure 2

Rumen tissue morphology of two groups. Rumen tissue morphology of the Con group at (A) 4.0× and (C) 10.0×; Rumen tissue morphology of the ATABG group at (B) 4.0× and (D) 10.0×.

Figure 3

Correlation matrix plot of rumen fluid indicators and rumen histomorphology. The Pearson correlation between two indicators is represented by a graph or a number at the intersection of the two indicators. The size of the circle in the lower left corner indicates the magnitude of the correlation between the indicators. Warm colors represent positive correlations, while cold colors represent negative correlations. Additionally, an asterisk (*) is used to denote a significant correlation (p < 0.05). In the upper right corner of the figure, corresponding to each graphic, the Pearson’s correlation coefficient is presented to indicate the correlation value between the two indicators. TVFA, total volatile fatty acids; AA, acetic acid; PA, propanoic acid; BA, butyric acid; A/P, acetic acid to propionic acid ratio; MCP, microbial protein; LPS, lipase; UE, urease; CL, cellulase; BAM, β-Amylase; RPL, rumen papillae length; RPW, rumen papillae width; RMT, rumen muscular layer thickness.

Figure 4

Average relative abundance of rumen microbial taxa and community diversity. (A) and (B) display the columnar composition plots of the average relative abundance of rumen bacteria at the phylum and genus levels. (C) presents the analysis of alpha diversity in the microbial composition of the two groups, with the asterisk (*) denoting a significant difference (Wilcoxon rank-sum tests, n = 20, p < 0.05). (D) shows the PCA analysis and (E) the NMDS analysis of the ruminal microbial composition of sheep based on the Bray–Curtis distance matrix analysis in the two groups.

Figure 5

LEfSe analysis of rumen bacterial composition. (A) displays LDA analysis, the vertical coordinates as the categorical units with significant differences between groups, and the horizontal coordinates display the logarithmic score values of the LDA analysis for each categorical unit. Longer lengths on the horizontal axis indicate more significant differences. The threshold for LDA is set to 4. The distribution of the relative abundance of differential categories across different phylum levels and genus level is shown (B), where solid and dashed lines represent the mean and median relative abundance of each categorical unit in each subgroup. The asterisk (*) denotes a significant difference (Wilcoxon rank-sum tests, n = 20, p < 0.05).

Figure 6

Correlation matrix plot presenting the associations between the indicators. (A) displays the Pearson correlation between the combined group of rumen fluid indicators and rumen histomorphology, and the combined group of growth performance and the apparent digestibility of nutrients. (B) displays the Spearman correlation between the combined group of rumen fluid indicators and rumen histomorphology, and the combined group of growth performance and the apparent digestibility of nutrients. Warm colors represent positive correlations, while cold colors represent negative correlations. Additionally, an asterisk (*) is used to denote a significant correlation (p < 0.05). EED, ether extract digestibility; BW, Body weight; ADG, average daily gain; DMI, dry matter intake; RFI, residual feed intake; MCP, microbial protein; LPS, lipase; CL, cellulase; RPL, rumen papillae length; RPW, rumen papillae width; RMT, rumen muscular layer thickness.