House feeding pattern increased male yak fertility by improving gut microbiota and serum metabolites

Abstract

Yaks usually live in an extremely harsh natural environment resulting in low reproductive performance, so the production of yak cannot meet local demand in China. In order to solve this problem, the experiment aims to explore the effect of different feeding modes on the semen quality of male yaks, so as to provide a theoretical basis for improving the yield of yaks in Tibet. We used the combined analysis of metabolomics and microbial sequencing to explore the underlying mechanisms that affect the differences in semen quality between the house feeding (HF) system and the free range (FR). The results showed that the sperm motility (P < 0.001) and sperm concentration (P < 0.05) in the HF group were significantly higher than the FR group, and the abnormal sperm rate (P < 0.01) in HF was significantly lower compared to FR. House feeding modes increased some beneficial materials in blood and testis especially some antioxidants, unsaturated fatty acids, and amino acids. House feeding group increased some gut microbiota at genus level namely Rikenellaceae, Bacteroides, Prevotellaceae_UCG-004, Bacteroidales_RF16, and Alloprevotella, DgA-11. It was interesting that blood metabolites, testicular metabolites, and fecal microbiota were well-correlated with sperm parameters. Meanwhile, the blood metabolites and testicular metabolites were well-correlated with microbes. The result indicated that the HF model was beneficial for yak semen quality by improving the gut microbiota and blood metabolism to increase yak fertility.

Keywords: free range; house feeding; metabolome; microbiota; reproductive performance; semen quality; yaks.

Figure 1

House feeding modes benefit yak semen quality. (A) Experimental design. (B) Sperm motility is determined by CASA, Y-axis = % of total sperm, X-axis = feeding modes. n = 10. ***P < 0.001. (C) Sperm concentration, Y-axis = sperm concentration (10⁸/ml), X-axis = feeding modes n = 10. *P < 0.05. (D) Abnormal sperm rate. Y-axis = % of abnormal sperm, X-axis = feeding modes. **P < 0.01.

Figure 2

(A,B) H&E-stained sections of yak testis in free range group under 10x microscope. The arrow in (A) means part of the connective tissue was broken in the FR group. The arrow in (B) means the space between the seminiferous tubules was enlarged, and the seminiferous tubules were also loosely arranged and structurally disordered. (C,D) H&E-stained sections of yak testis in house feeding group under 10x microscope.

Figure 3

House feeding modes benefited yak blood metabolome. (A–L) Increased blood metabolites Y-axis = relative amount, X-axis = feeding modes **P < 0.01. (M) Correlation of blood metabolites and sperm concentration, motility, and abnormal sperm rate. *P < 0.05.

Figure 4

House feeding modes benefited yak testicular metabolome. (A–O) Increased testicular metabolites Y-axis = relative amount, X-axis = feeding modes **P < 0.01; *P < 0.05.

Figure 5

(A) Correlation between testicular metabolites and sperm parameters. (B) Correlation between blood metabolites and testicular metabolites. *P < 0.05.

Figure 6

House feeding modes improved yak gut microbiota. (A) The Wayne figures of fecal microbiota. (B) The Chao 1 index of fecal microbiota. (C) PC analysis of fecal microbiota at the OUT level. (D) Difference bacterial abundance at the phylum level. (E) The relative abundances of fecal microbiota at the genus level. (F–K) The relative abundances of six different microbes in the genus level, which were increased in house feeding modes. **P < 0.01; *P < 0.05.

Figure 7

(A) Correlation between gut microbes and sperm parameters. (B) Correlation between blood metabolites and gut microbes. (C) Correlation between testicular metabolites and gut microbes. *P < 0.05.