Differential Effects of Natural Grazing and Feedlot Feeding on Yak Fecal Microbiota

Abstract

Variation in food and diet shapes the diversity of the gut microbiota of ruminants. The present study investigated the microbial diversity in the fecal microbiota of yaks reared under natural grazing and feedlot system. A total of 48 domestic yaks with an average age of 7.5 years were selected from two different grazing habitats: one group grazed on natural pasture (grazing yaks—GY) while the other group was fed fodder and concentrate (feedlot yaks—FY). Crude protein, non-fiber carbohydrate, hemicelluloses, and digestible dry matter contents of natural pastures were higher than those in the feedlot. The lower insoluble fiber contents were found in grazing land. The 16S rRNA gene sequencing revealed 675 and 348 unique operational taxonomic units (OTUs) in the GY and FY, respectively, in addition to 1,778 common OTUs. Overall, a total of 9,891 OTUs were identified as a whole, of which 6,160 OTUs were from GY and 3,731 were from FY. Shannon index analysis revealed a higher bacterial diversity in GY than FY. At the phylum level, Firmicutes were dominant bacterial taxa in both groups. The relative abundance of Firmicutes in GY (56% ± 0.05) was higher than in FY (41% ± 0.08). At the family level, GY had a significantly higher abundance of Ruminococcaceae (p < 0.001) and Rikenellaceae (p < 0.001) than FY, but FY had a significantly higher abundance of Prevotellaceae than GY (p < 0.001). At the genus level, abundances of Faecalibacterium, Alloprevotella, and Succinivibrio were higher in FY than in GY. This study presents novel information on fecal bacterial composition and diversity in yaks reared under two different production systems.

Microbiota and Serum Metabolic Profile Changes in Korean Native Hanwoo Steer in Response to Diet Feeding Systems

“…GS had higher Firmicutes content ( p < 0.05) and lower Bacteroidetes content ( p < 0.009) in fecal samples compared with HS. This is consistent with what has been previously reported for other animals, including Angus steer [ 17 , 33 ] and yaks [ 16 ]. As compared with what we reported in the current study regarding other animals, there is a large variation in the ratio of Firmicutes to Bacteroidetes in cattle reported in previous studies [ 16 , 17 , 33 ].…”

“…This is consistent with what has been previously reported for other animals, including Angus steer [ 17 , 33 ] and yaks [ 16 ]. As compared with what we reported in the current study regarding other animals, there is a large variation in the ratio of Firmicutes to Bacteroidetes in cattle reported in previous studies [ 16 , 17 , 33 ]. According to these previous studies, the dominance of Firmicutes or Bacteroidetes is due to variations in diets, breed types, climate, and forming practices across a wide geographical range [ 34 ].…”

“…The fiber-based diet contains several secondary metabolites that can act as prebiotics and contribute to the improvement of bacterial diversity [ 29 , 30 ]. During this study, animals grazed a variety of pastures containing large amounts of non-structural carbohydrates (NSC) and non-fiber carbohydrates (NFC) in tall fescue orchard grass, perennial ryegrass, Kentucky bluegrass, and white clover [ 16 , 31 ]. Microbial diversity depends on both NSCs and NFCs.…”

“…The majority of pyrotags in the fecal samples of GS and HS belong to the Bacteroidetes (49.90 ± 4.31 vs. 57.23 ± 4.4%, respectively; p < 0.047) and Firmicutes (40.85 ± 2.99 vs. 34.5 ± 2.4% respectively; p < 0.09). These phyla have previously been demonstrated to constitute the major gut-associated phylotypes in a variety of different mammalian species [ 16 , 17 , 19 ], suggesting that Firmicutes and Bacteroidetes (more than 90% of all high-quality bacterial pyrotags) are critical to the microbial ecology of mammalian guts. Phyla such as Spirochaetes and Verrucomicrobia accounted for less than 2% of the total sequences, while unclassified bacteria accounted for less than 1%.…”

“…Moreover, recent next-generation sequencing (NGS) studies have demonstrated that the enteric microbiota shifts in response to animal performance across multiple species. Particularly in cattle, diets/feed additives/feed methods contribute to changes in rumen and fecal microbial communities [ 16 , 17 , 18 , 19 ], as well as animal welfare. Nonetheless, potential changes in the microbial communities of grazing cattle, including orchard grass, perennial ryegrass, Kentucky bluegrass, white clover, and tall fescue have not been thoroughly studied.…”