Epizootic rabbit enteropathy (ERE) is reproduced successfully in the present study by feeding rabbits a low-fibre diet, and high-throughput sequencing and quantitative real-time PCR (qPCR) analysis were applied to examine the microbial variations in the stomach, small intestine and caecum. The evenness was disturbed and the richness was decreased in the ERE groups. When the rabbits were suffering from ERE, the abundance of the Firmicutes was decreased in three parts of the digestive tract, whereas the Proteobacteria was increased in the stomach and caecum, the Bacteroidetes and Verrucomicrobia were increased in the small intestine. Correlation analysis showed that the reduced concentrations of TVFA and butyrate in the caeca of the ERE group were attributed to the decreased abundances of genera such as Lactobacillus, Alistipes and other fibrolytic bacteria and butyrate- producing bacteria such as Eubacterium and Faecalibacterium. It is concluded that, in terms of microorganisms, the overgrowth of Bacteroides fragilis, Clostridium perfringen, Enterobacter sakazakii and Akkermansia muciniphila and inhibition of Bifidobacterium spp. and Butyrivibrio fibrisolvens in the stomach, small intestine and caecum resulted in a decrease in butyrate yield, leading to the incidence of ERE, and the probability of developing ERE could be manipulated by adjusting the dietary fibre level.

The aim of the current research was to investigate the effects of betaine (Bet) supplementation on the production performance, rumen fermentation, digestibility, and serum indexes of dairy cows. Thirty healthy Holstein cows with the same parity (milk production = 22 ± 2.5 kg) were randomly selected and divided into three groups. One group served as a control group (CON; no betaine); the other two groups were Bet1 (15 g/d per cow) and Bet2 (30 g/d per cow). All cows were fed regularly three times a day at 06:00, 14:00, and 22:00 h. Cows received the formulate diet, and water was provided ad libitum. The experiment lasted for 60 days during the summer season. Results showed that the dry matter intake, milk protein, and fat of Bet1 cows was significantly higher (p < 0.05) than that in other groups. The content of volatile fatty acid (VFA) in Bet1 was significantly higher (p < 0.05) than CON. Consistent with VFA, a similar trend was found in acetate, while propionate exhibited an opposite trend. Compared to other groups, the microbial protein (MCP) concentrations of Bet1 increased (p < 0.05). The apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) of Bet1 was significantly higher (p < 0.05) than CON. The serum concentration of total antioxygenic capacity (T-AOC) in Bet1 and Bet2 was significantly increased (p < 0.05). Furthermore, the contents of malonaldehyde (MDA) and superoxide dismutase (SOD) in Bet2 were higher (p < 0.05) than that in other groups. Compared to CON and Bet2, Bet1 significantly increased (p < 0.05) the serum concentrations of glucose. Therefore, it is practicable to feed betaine to lactating cows to improve their performance in heat stress.

The intensity and specialization of beef cattle production make off-site fattening, and introduce new breeds need transportation to achieve the goals. The present study was aimed to investigate effects of land transport stress on hormones levels, microbial fermentation, microbial composition, immunity and correlation among them among Simmental Crossbred Cattle (SC), Native Yellow Cattle (NY), and Cattle Yak (CY). High-throughput sequencing was used to investigate the rumen microbial diversity. After transport stress cortisol (COR), adrenocorticotropic hormone (ACTH) and pro-inflammatory cytokines IL-6, TNF-α, and IL-1β were increased (p < 0.05) in all groups. Rumen lipopolysaccharide (LPS) was increased (p < 0.05) in SC and CY groups. Total volatile fatty acids were increased (p < 0.05) in all groups. The ruminal microbiota about OTUs, Chao1, and Shannon in SC and CY groups were higher than before transport. Prevotella1 in NY group was higher (p < 0.05) than other groups before transport; after transport Firmicutes and Lactobacillus were increased (p < 0.05) than other groups in CY. Lactobacillus was positively correlated with IL-6 and IL-4. Under transport stress, cattle may suffer from inflammatory response through modulating HPA axis and microbiota metabolite affects the secretion of hormone levels and immune function and breeds factor affect the performance of stress resistance.

Yak suffers severe starvation and body weight reduction in the cold season and recovers relatively rapid growth in the warm season every year. Herein, we investigated the effects of starvation and refeeding on the growth, feed efficiency, blood biochemistry and rumen microbial community as well as functions of yaks. The results showed that starvation significantly reduced the body weight of yaks. Serum glucose and triglyceride concentrations significantly decreased, and β-hydroxybutyric acid and non-esterified fatty acid levels were significantly increased during the starvation period. Starvation also dramatically inhibited rumen microbial fermentations. Whereas, refeeding with the same diet significantly increased the feed efficiency, nutrient digestibility together with rumen acetate, propionate and microbial protein productions compared with those before starvation. The 16S rDNA sequencing results showed that starvation mainly decreased the ruminal protein-degrading bacteria Prevotella and propionate-producing bacteria Succiniclasticum populations and dramatically increased the denitrifying bacteria Thauera populations. Refeeding reduced the Euryarchaeota population and increased propionate-producing bacteria Succinivibrionaceae UCG-002 and starch-degrading bacteria Ruminobacter populations when compared with those before starvation. The predicted microbial metabolic pathways, related to amino acid and starch metabolisms, were also significantly altered during the starvation and refeeding. The results indicated that the rumen microorganisms and their metabolism pathways changed with feed supply, and these alterations in part contributed to yak adaption to starvation and re-alimentation. This study is helpful for enhancing the understanding and utilization of this natural character of yaks to explore and improve their growth potential.

The yak rumen microflora has more efficient fiber-degrading and energy-harvesting abilities than that of low-altitude cattle; however, few studies have investigated the effects of dietary energy levels on the rumen bacterial populations and the relationship between rumen bacteria and the intramuscular fatty acid profile of fattening yaks. In this study, thirty yaks were randomly assigned to three groups. Each group received one of the three isonitrogenous diets with low (3.72 MJ/kg), medium (4.52 MJ/kg), and high (5.32 MJ/kg) levels of net energy for maintenance and fattening. After 120 days of feeding, results showed that increasing dietary energy significantly increased ruminal propionate fermentation and reduced ammonia concentration. The 16S rDNA sequencing results showed that increasing dietary energy significantly increased the ratio of Firmicutes to Bacteroidetes and stimulated the relative abundance of Succiniclasticum, Saccharofermentans, Ruminococcus, and Blautia populations. The quantitative real-time PCR analysis showed that high dietary energy increased the abundances of Streptococcus bovis, Prevotella ruminicola, and Ruminobacter amylophilus at the species level. Association analysis showed that ruminal acetate was positively related to some intramuscular saturated fatty acid (SFA) contents, and Prevotella was significantly positively related to intramuscular total polyunsaturated fatty acid content and negatively related to intramuscular total SFA content. This study showed that high dietary energy mainly increased ruminal amylolytic and propionate-producing bacteria populations, which gave insights into how the effects of dietary energy on rumen bacteria are related to intramuscular fat fatty acids of fattening yaks.

In vivo rumen fermentation. Rumen content from each steer was collected at 0, 3, 6, 9, and 12 h after morning feeding through the ruminal cannula on the last day of in vivo treatment period (30 d) and filtered by four layers of gauze. pH was measured immediately. Samples were then stored at −20°C for analysis of VFA concentration using the same instrument described above. Ruminal lactate was detected by a commercial kit purchased from Nanjing Jiancheng Biochemical Reagent Co., (Nanjing, China). Another aliquot of rumen fluid was transferred into −80°C for microbial population analysis.