This study aims to study the differences in rumen fermentation parameters and microbial communities between Holstein steer and Xiangxi cattle. It provided a reference for exploring the composition and functional characteristics of rumen microbial ecosystems in animals with different genetic backgrounds, and offered a scientific basis for the formulation of breed-specific feeding strategies. Twelve adult Holstein steer (241.3±9.1 kg) and twelve adult Xiangxi cattle (206.0±8.4 kg) with good body condition were selected as experimental subjects and all animals were fed their respective standard diets. The experimental procedure involved the collection of ruminal fluid for the determination of ruminal fermentation parameters. Additionally, 16S rRNA sequencing was applied to analyze the structure and function of the ruminal microbial community. The results showed that: 1) The dry matter digestibility (DMD), organic matter digestibility (OMD), neutral detergent fiber digestibility (NDFD), and acid detergent fiber digestibility (ADFD) in Xiangxi cattle were significantly higher than those in Holstein steer (P<0.001). 2) The ruminal pH in Xiangxi cattle was significantly higher than that in Holstein steer (P<0.001). The concentrations of dissolved hydrogen (dH2), dissolved methane (dCH4), and ammonia nitrogen (NH3-N) in Xiangxi cattle were significantly lower than those in Holstein steer (P<0.001), while the dissolved hydrogen to dissolved methane ratio (dH2/dCH4) was significantly higher in Xiangxi cattle than Holstein steer (P<0.001). In rumen fermentation products, the total volatile fatty acid (TVFA) concentration and molar ratios of propionate, butyrate, iso-butyrate, valerate, and iso-valerate were higher in Holstein steer, while the molar ratios of acetate and acetate to propionate ratio were higher in Xiangxi cattle (P<0.001). 3) The results of α-diversity showed that Xiangxi cattle possessed richer and more diverse rumen microbial communities. In comparison, it was found that Holstein steer were primarily differentially enriched functional bacteria such as Agathobacter, Butyrivibrio and Lachnospira while functional bacteria differentially enriched in Xiangxi cattle included Fibrobacteres, Saccharofermentans, Lentimicrobium, Succiniclasticum and Acetatifactor (P<0.05). 4) The pathways of carbohydrate metabolism and metabolism of other amino acids were significantly enriched in Holstein steer, and the nucleotide metabolism and biosynthesis of other secondary metabolites pathways were significantly enriched in Xiangxi cattle (P<0.05).These results showed that there were significant differences in nutrient digestibility, rumen fermentation parameters and microbial communities between Holstein steer and Xiangxi cattle. Specifically, the rumen of Holstein steer was inclined to propionate-type fermentation mode and was more capable of digesting non-fiber plant polysaccharides and proteins, while the rumen of Xiangxi cattle was inclined to acetate-type fermentation mode and was more capable of digesting fiber.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |