Table 2. Effect of bacteria-based products on ruminant performance.

Animal/study design	Diet	Product	Dose	Effects†	Reference
Rumen-fistulated dairy cows	F:C was 60:40	Prevotella bryantii (25A)	2 × 1011 cells/dose per animal daily	↕ Feed intake. ↕ Milk production. ↕ Rumen pH. ↓ Ruminal lactate concentration. ↑ Ruminal concentration of NH3-N. ↑ Acetate, butyrate, and branched-chain C4 fatty acid concentrations. ↕ Acidosis.	[37]
Holstein cows	Corn and ryegrass silages	Combination of Lactobacillus acidophilu NP51 and Propionibacterium freudenreichii NP24	4 × 109 CFU/h per day	↕ Feed intake. ↑ Milk yield. ↑ Energy-corrected milk. ↕ Milk fat and protein percentages. ↑ Milk protein yield. ↕ Respiratory rate, skin temperature, body temperature. ↑ Apparent digestibility.	[75]
Male and female Holstein calves	Calf starter feed	Megasphaera elsdenii	50 mL oral dose of M. elsdenii NCIMB 41125 (108 CFU/mL) per calf daily	↑ Starter DM intake. ↑ Weaning body weight. ↑ Plasma β-hydroxybutyrate concentration. ↑ Reticulo-rumen weight. ↑ Papillae width and papillae density. ↕ Total VFA, acetate and propionate production. ↑ Butyrate production.	[34]
Crossbreed of Japanese black cattle and Red Angus cattle	Total mixed ration	Bacillus amyloliquefaciens C-1 and B. subtilis	4 × 1010 CFU/calf daily	↑ Body weight gain. ↑ Feed intake. ↑ Efficient feed conversion rate. ↑ Proteobacteria, Rhodospirillaceae, Campylobacterales, and Butyricimonas. ↓ Pathogens. ↑ Akkermansia.	[40]
Murrah buffalo calves	Total mixed ration	Lactobacillus acidophilus	Fermented milk containing 200 mL/calf/day (108 CFU/mL)	↑ Final body weight. ↑ DM intake. ↑ Average daily gain. ↑ Feed conversion efficiency. ↑ Digestibility of fiber. ↑ The fecal lactobacilli and bifidobacterium population. ↓ Fecal coliform count. ↑ The fecal VFA.	[20]
Murrah buffalo calves	Total mixed ration	Lactobacillus acidophilus	Fermented milk containing 200 mL/calf/day (108 CFU/mL)	↑ Final body weight. ↑ DM intake. ↑ Average daily gain. ↑ Feed conversion efficiency. ↑ Digestibility of fiber. ↑ The fecal lactobacilli and bifidobacterium population. ↓ Fecal coliform count. ↑ The fecal VFA.	[20]
Saanen dairy goats	Total mixed ration	Bacillus subtilis and Enterococcus faecalis	5 g per goat daily (5 × 1,011 CFU/goat per day)	↑ DM intake. ↑ milk yield. ↑ Protein and lactose percentage with B. subtilis. ↕ Bacterial abundance and diversity. ↑ Succinivibrionaceae.	[76]
Lactating Friesian cows	F:C was 50:50	Lactiplantibacillus plantarum, Lactobacillus gasseri, Leuconostoc mesenteroides and Bifidobacterium breve	20 g/kg silage	↓ Silage contents of oxalic acid and fibers. ↑ Silage content non-structural carbohydrate and calcium. ↕ Milk production. ↑ Energy-corrected milk. ↕ Feed efficiency. ↓ Feed intake. ↓ Total ruminal VFA, acetate and propionate concentrations. ↑ Milk total solids, fat, protein and energy.	[77]
Farafra lambs	F:C was 40:60	Bacillus subtilis and Phanerochaete chrysosporium	2 and 4 g per lamb daily	↑ Live-weight gain. ↓ Roughage and total feed intake. ↑ Feed efficiency. ↑ Serum total protein, globulin, urea-N, aspartate aminotransferase and alanine aminotransferase. ↑ Hot carcass weight and dressing percentage. ↓ Tail fat and all fat levels.	[39]
Sheep and lambs	Concentrate with freely available bean and cereal hay	Bacillus subtilis B-2998D, B-3057D, and Bacillus licheniformis B-2999D	1 and 3 g per animal daily	↑ Body weight gain. ↑ Blood total protein, globulins, and urea. ↓ Bilirubin and cholesterol. ↑ Bactericidal and phagocytic index. ↑ Fecal Lactobacillus and Bifidobacterium. ↓ Fecal Escherichia coli, Enterococcus, and yeast.	[43]
Farafra male lambs	F:C was 30:70	2 × 1011 CFU of Bacillus subtilis/g or 1 × 1012 CFU of Lactobacillus acidophilus/g or 6 × 108 CFU of Ruminococcus albus/g	4 g product per lamb daily	↑ Growth performance and feed efficiency. ↑ Concentrations of albumin, triiodothyronine, thyroxine, hemoglobin and red blood cells. ↓ Globulin and urea-N. ↑ Hot carcass. ↑ Longissimus dorsi with B. subtilis. ↕ Water holding capacity. ↑ Digestibility of crude protein with B. subtilis. ↑ Digestibility of DM, OM, and fiber with B. subtilis and R. albus. ↕ N intake and urinary N. ↓ Fecal N. ↑ N balance. ↑ Ruminal VFA with B. subtilis and R. albus.	[78]
Lactating Farafra ewes	F:C at 40:60	Bacillus subtilis and Bacillus lichenifomis	4 g product/kg DM feed (each g of the product contained 1.75 × 1012 CFU B. subtilis and 1.75 × 1012 CFU B. lichenifomis)	↑ Total intake. ↑ Digestibility of all nutrients. ↑ Concentrations of ruminal ammonia ↑ Concentration of total VFA, acetate and propionate. ↑ Milk production. ↑ Concentrations of milk fat, lactose and energy. ↑ Concentrations of total n3, n6 fatty acids, PUFA and CLA. ↓ Aatherogenicity.	[79]
In vitro (Rumen inoculum was collected from sheep)	F:C was 50:50	Bacillus subtilis and Bacillus lichenifomis	4 g product/kg DM feed (each g of the product contained 1.75 × 1012 CFU B. subtilis and 1.75 × 1012 CFU B. lichenifomis)	↓ Asymptotic production of total gas, CH4 and CO2. ↓ Rate of CH4 and CO2. ↑ Lag time of CH4 and CO2 production. ↑ Total bacterial count. ↑ Fermentation pH and VFA. ↓ Protozoal count.	[80]
Ongole breed cattle		Lactiplantibacillus plantarum (1.8 × 1010 CFU/mL)	10, 20 and 30 mL/cow daily	↓ Ruminal acetate. ↑ Ruminal propionate. ↓ Ruminal protozoal number. ↕ Ruminal L. plantarum. ↕ Ruminal Ruminococcus flavefaciens. ↕ Ruminal Treponema bryantii. ↑ Ruminal Ruminococcus albus.	[41]
A meta-analysis study	Different diets	Megasphaera elsdenii	Different doses	↑ Ruminal propionate, butyrate, isobutyrate, and valerate. ↓ Ruminal lactic acid concentration, acetate proportion. ↓ Ruminal total bacterial population. ↓ CH4 emission. ↑ Average daily gain and body condition score. ↑ Carcass quality. ↑ Hot carcass weight. ↑ Carcass gain. ↓ Diarrhea, bloat incidences and liver abscess.	[33]

CFU = colony forming unit, CLA = conjugated linoleic acids, DM = dry matter, F:C = Forage:concentrate ratio, PUFA = polyunsaturated fatty acids, VFA = volatile fatty acids, UFA = unsaturated fatty acids, ↑ = increased, ↓ = decreased, ↕ = no effect. ^†Effect is relative to control.