Table 1 Factors that influence the development of gut microbiota of ruminants

Probiotics

Preweaning calves

Calves were inoculated through a rumen cannula with 250 mL of skim milk that contained potential probiotics isolated from the cow intestine (10¹⁰ CFU)

Probiotics reduced the level of carriage of E. coli O157:H7

[105]

Calves at 7–56 d

Lactobacillus acidophilus or Bifidobacterium pseudolongum were administered every morning with milk replacer (3 × 10⁹ CFU)

Body weight was increased, and feed conversion and fecal score were improved

[106]

Newborn Holstein calves

Compound probiotics that contained Bifidobacterium thermophilum (10¹⁰ CFU), Enterococcus faecium (10¹⁰ CFU), and Lactobacillus acidophilu (10⁹ CFU) were administered every morning with milk replacer

Increased body weight and reduced diarrhea incidence

[106]

Newborn Holstein calves

Calves were fed milk daily with compound probiotics that contained Lactococcus lactis, Pediococcus pentosaceus, Lactobacillus plantarum, Saccharomyces cerevisiae, and Kluyveromyces marxianus (at the total dose of 2 × 10¹⁰ CFU)

Calves in the compound probiotic group had closer intestinal microbiota and lower rates of diarrhea than those in the control group

[65]

Weaned calves at 78.3 ± 7.2 d

Calves were fed Lactobacillus plantarum and Bacillus subtilis (0.2 kg/ton feed)

Diarrhea was inhibited

[107]

Newborn Holstein calves

Saccharomyces cerevisiae (2 × 10⁸ CFU), Lactobacillus acidophilus (2 × 10⁸ CFU), Lactobacillus plantarum (2 × 10⁸ CFU), Lactobacillus rhamnosus (2 × 10⁸ CFU), Lactobacillus casei (2 × 10⁸ CFU), Bifidobacterium bifidium (2 × 10⁸ CFU), Pediococcus acidilactici (2 × 10⁸ CFU), Bacillus subtilis (2 × 10⁹ CFU), and Enterococcus faecium (2 × 10⁸ CFU)

Digestion of NDF, growth preference, and rumen fermentation improved

[108]

Diet

Beef steers

Beef steers were fed with the step-up diets that contained grain and hay at ratios of 20:80, 40:60, 60:40, and 80:20

Megasphaera elsdenii, Streptococcus bovis, Selenomonas ruminantium, and Prevotella bryantii increased, while Butyrivibrio fibrisolvens and Fibrobacter succinogenes decreased in the rumen by high-concentrate diet

[109]

Dairy cows

Cows were fed different ratios of fiber (88%, 76%, and 57.5%)

Fiber increased the population of Firmicutes (e.g., Ruminococcus, Butyvibrio, Pseudobutyrivibrio, Oscillibacter, and Eubacterium) and Fibrobacter

[110]

Dairy cows

Cows were fed a low-fiber, high-PUFA (polyunsaturated fatty acid) diet or a high-fiber, low-PUFA diet for 21 d

Prococcus and Filamentous bacilli and increased Rumenomonas, and Megafococcus ellieri decreased by a high-fiber, low-PUFA diet

[111]

Beefs

Beefs were fed different ratios of forage and concentrate (500:500 and 80:920) diets

High forage avoided dysbiosis associated with pathogenic species among Proteobacteria, and high forage increased drug-resistant bacteria and diseased related bacteria in the rumen

[112]

Age

Newborn calves

Newborn calves were fed for 14 or 42 d

Gut microbiome structure was different between the two age groups (14 and 42 d). Oscillibacter and Paraprevotella had a high richness at only 14 d, whereas Porphyromonas had higher richness at 42 d

[113]

Newborn calves

From birth to 7-week-old

Chao1 index of the gut microbiome of calves increased from 0 to 7 weeks. Fusobacteria decreased gradually. Lactobacillus spp. and Bifidobacterium spp. reached a maximum of 15% at 4-week-old, and then decreased to 2%

[114]

Newborn calves

From birth to adulthood

The rumen microbiota had significant age-related changes. Age decreased the diversity of bacteria and increased anaerobic bacteria and aerobic bacteria

[8]

Genotype

Twin and singleton calves

The twin calves had the same microbial community structure

[115]

Herbivorous ruminants and non-ruminants

The community structure of different genotypes was different

[116]

India cattle and buffalo

Indian cattle had a higher abundance of total anaerobic fungi and Ruminococcus flavefaciens. Buffalo had a higher abundance of cellulolytic bacteria Fibrobacter succinogenes and Ruminococcus albus

[117]

Holstein and Jersey cows

Rumen microbiota was influenced by host species

[118]