Shrub coverage alters the rumen bacterial community of yaks (Bos grunniens) grazing in alpine meadows
Proliferation of shrubs at the expense of native forage in pastures has been associated with large changes in dry-matter intake and dietary components for grazing ruminants. These changes can also affect the animals’ physiology and metaboli...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Korean Society of Animal Sciences and Technology
2020-07-01
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| Series: | Journal of Animal Science and Technology |
| Subjects: | |
| Online Access: | http://www.ejast.org/archive/view_article?pid=jast-62-4-504 |
| Summary: | Proliferation of shrubs at the expense of native forage in pastures has been
associated with large changes in dry-matter intake and dietary components for
grazing ruminants. These changes can also affect the animals’ physiology
and metabolism. However, little information is available concerning the effect
of pastoral-shrub grazing on the rumen bacterial community. To explore rumen
bacteria composition in grazing yaks and the response of rumen bacteria to
increasing shrub coverage in alpine meadows, 48 yak steers were randomly
assigned to four pastures with shrub coverage of 0%, 5.4%, 11.3%, and 20.1%
(referred as control, low, middle, and high, respectively), and ruminal fluid
was collected from four yaks from each pasture group after 85 days. Rumen
fermentation products were measured and microbiota composition determined using
Ion S5TM XL sequencing of the 16S rRNA gene. Principal coordinates
analysis (PCoA) and similarity analysis indicated that the degree of shrub
coverage correlated with altered rumen bacterial composition of yaks grazing in
alpine shrub meadows. At the phyla level, the relative abundance of
Firmicutes in rumen increased with increasing shrub
coverage, whereas the proportions of Bacteroidetes,
Cyanobacteria and Verrucomicrobia
decreased. Yaks grazing in the high shrub-coverage pasture had decreased species
of the genus Prevotellaceae UCG-001,
Lachnospiraceae XPB1014 group,
Lachnospiraceae AC2044 group,
Lachnospiraceae FCS020 group and
Fretibacterium, but increased species of
Christensenellaceae R-7 group,
Ruminococcaceae NK4A214 group,
Ruminococcus 1, Ruminococcaceae UCG-002,
Ruminococcaceae UCG-005 and
Lachnospiraceae UCG-008. These variations can enhance the
animals’ utilization efficiencies of cellulose and hemicellulose from
native forage. Meanwhile, yaks grazed in the high shrub-coverage pasture had
increased concentrations of ammonia nitrogen (NH3-N) and
branched-chain volatile fatty acids (isobutyrate and isovalerate) in rumen
compared with yaks grazing in the pasture without shrubs. These results indicate
that yaks grazing in a high shrub-coverage pasture may have improved dietary
energy utilization and enhanced resistance to cold stress during the winter. Our
findings provide evidence for the influence of shrub coverage on the rumen
bacterial community of yaks grazing in alpine meadows as well as insights into
the sustainable production of grazing yaks on lands with increasing shrub
coverage on the Qinghai-Tibet Plateau. |
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| ISSN: | 2672-0191 2055-0391 |