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Assessing the impact of biotics on the ruminal microbiome to enhance sustainability, welfare, and performance in beef cattle: highlighting the omics approach

Italian Journal of Animal Science

February 2025
24(1):660-676

DOI:10.1080/1828051X.2025.2465703

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CC BY 4.0

Authors:

Stefano Bettini

University of Perugia

Francesco Perini

University of Perugia

Daniele Colombi

University of Perugia

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Italian Journal of Animal Science

ISSN: (Print) (Online) Journal homepage: www.tandfonline.com/journals/tjas20

Assessing the impact of biotics on the ruminal

microbiome to enhance suﬆainability, welfare, and

performance in beef cattle: highlighting the omics

approach

Stefano Bettini, Francesco Perini, Daniele Colombi, Marco Ghilardi, Massimo

Trabalza-Marinucci & Emiliano Lasagna

To cite this article: Stefano Bettini, Francesco Perini, Daniele Colombi, Marco Ghilardi,

Massimo Trabalza-Marinucci & Emiliano Lasagna (2025) Assessing the impact of biotics

on the ruminal microbiome to enhance sustainability, welfare, and performance in beef

cattle: highlighting the omics approach, Italian Journal of Animal Science, 24:1, 660-676, DOI:

10.1080/1828051X.2025.2465703

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REVIEW ARTICLE

Assessing the impact of biotics on the ruminal microbiome to enhance

sustainability, welfare, and performance in beef cattle: highlighting the

omics approach

Stefano Bettini

, Francesco Perini

, Daniele Colombi

, Marco Ghilardi

Massimo Trabalza-Marinucci

and Emiliano Lasagna



Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, University of Perugia, Perugia, Italy;

Dipartimento di Agronomia,

Animali, Alimenti, Risorse naturali e Ambiente, University of Padova, Legnaro, Italy;

Dox-al Italia S.p.A, Sulbiate, Italy;

Dipartimento

di Medicina Veterinaria, University of Perugia, Perugia, Italy

ABSTRACT

Enhancing the development of the microbiome is a key strategy for modulating ruminal fermen-

tation and improving production efficiency in ruminants. The inclusion of probiotics, prebiotics,

synbiotics, and postbiotics (biotics) in animals’ feeds has become a common method to reach

these goals. The proven benefits of these additives in human health have helped their increased

application in livestock to enhance overall health and reduce reliance on medications, particu-

larly antibiotics. Recent scientific research has focused on elucidating the mechanisms of how

these additives impact ruminants’ performance and health. Advances in Next Generation

Sequencing and the decrease in associated costs have made -omics technologies more access-

ible. These technologies provide valuable insights into how dietary biotics influence gastrointes-

tinal microbiota and their effects on ruminant performance and health. This review highlights

recent advancements in the application of biotics in beef production, and assesses their impact

on modifying the ruminal environment, fermentation, and microbiota, along with their implica-

tions for cattle health and productivity.

HIGHLIGHTS

The mechanisms of biotic feed supplementation in improving beef cattle performance and

welfare are not fully understood.

The use of genetic tools is crucial to study microbiome and host interactions affecting biotic

effectiveness.

Improving animal efficiency and health through biotic administration is a valid strategy to

enhance economic viability and sustainability.

ARTICLE HISTORY

Received 14 October 2024

Revised 20 January 2025

Accepted 5 February 2025

KEYWORDS

Probiotics; prebiotics;

synbiotic; postbiotic;

metagenomics

Introduction

Due to the expected increase in the world population,

the agricultural sector must improve production effi-

ciency while maintaining sustainability. While the

debate on the contribution of livestock farming to

greenhouse gas (GHG) emissions is still ongoing, con-

sumer concern regarding livestock resource consump-

tion and GHG emissions has been increasing in recent

years (Tedeschi et al. 2015; Correddu et al. 2023).

To achieve this goal, researchers in animal science

must focus on developing viable, safe, natural, and

sustainable strategies to improve production efficiency

and sustainability. The use of probiotics, prebiotics,

synbiotics and postbiotics (hereafter collectively

referred to as “biotics”) has gained extensive recogni-

tion as safe and sustainable additives, offering benefits

in enhancing animal performance, fortifying immune

responses, modulating metabolic patterns, and foster-

ing overall well-being (Uyeno et al. 2015; Khan et al.

2016; Ogbuewu et al. 2019; Adli et al. 2023).

Several studies have exploited the high throughput

of Next Generations Sequencing (NGS) to characterise

microbial communities by sequencing phylogenetic

markers and to shed light on the complex microbial

processes in the rumen (Henderson et al. 2015; Kim

et al. 2017; Scicutella et al. 2023). The NGS techniques

CONTACT Stefano Bettini stefano.bettini@dottorandi.unipg.it; Francesco Perini francesco.perini@unipd.it

These authors equally contributed to this work.

� 2025 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits

unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the

posting of the Accepted Manuscript in a repository by the author(s) or with their consent.

ITALIAN JOURNAL OF ANIMAL SCIENCE

2025, VOL. 24, NO. 1, 660–676

https://doi.org/10.1080/1828051X.2025.2465703

enable researchers to identify specific microbial strains

and functions. By elucidating the complex interactions

between host and microbiota, these studies can

inform the development of targeted biotics that opti-

mise the gut environment, enhance feed efficiency,

and improve growth performance in livestock

(Mamuad et al. 2019; Vasta et al. 2019).

Materials and methods

An extensive analysis of the existing literature on the

use of biotics in beef cattle has been conducted, with a

focus on their impacts on the gastrointestinal tract to

enhance performance and health. The scientific litera-

ture reviewed in this article was retrieved from the

Scopus and Google Scholar databases using the key-

words “probiotics”, “prebiotics”, “synbiotic”, “postbiotic”,

“beef cattle”, “rumen”, “microbiota”, “health”, and

“performance”. Given the lack of studies that simultan-

eously evaluate both performance and effects on

gastrointestinal microbiota and environment, we identi-

fied articles that examined either performance or

gastrointestinal effects while focusing on similar ani-

mals and biotic products. This review aims to explore

the efficacy of administering biotics to modulate micro-

biota and rumen ecosystem, using insights from

molecular genetics studies to investigate the key mech-

anisms of their positive impacts on animal health and

productivity.

Probiotics, prebiotics, synbiotics and

postbiotics: general definitions

The concept of probiotics was first described as sub-

stances that improve the health of malnourished

patients. In 2014, the World Health Organisation

(WHO) and the Food and Agriculture Organisation

(FAO) defined probiotics as "live microorganisms that,

when administered in adequate amounts, confer a

health benefit on the host" (Food and Agricultural

Organization of the United Nations and World Health

Organization 2002; Hill et al. 2014). For probiotics to

be effective, they should benefit the host, be non-

pathogenic and non-toxic, resist the gut environment,

and effectively colonise the gastrointestinal tract

(Fuller 1992).

Gibson and Roberfroid introduced prebiotics con-

cepts in 1995, defining them as non-digestible food

ingredients that selectively stimulate the growth and/or

activity of specific microbes in the gut (Gibson and

Roberfroid 1995). The International Scientific Association

of Probiotics and Prebiotics (ISAPP) later defined

prebiotics as "a substrate that is selectively utilised by

host microorganisms, conferring a health benefit" (Gibson

et al. 2017). Prebiotics must resist gastric acidity, pro-

mote fermentation by beneficial microbes, and select-

ively stimulate beneficial intestinal bacteria (Callaway

and Ricke 2023).

Synbiotics, combining probiotics and prebiotics,

were also defined by Gibson and Roberfroid in 1995.

ISAPP updated the definition in 2019 to "a mixture com-

prising live microorganisms and substrate(s) selectively

utilised by host microorganisms that confers a health

benefit on the host". Therefore synbiotics should show

superior benefits over individual probiotics or prebiotics

(Markowiak and 

Sli_

zewska 2017; Swanson et al. 2020).

In a recent study by Pimentel et al. (2023), the term

"postbiotics" was introduced. Unlike probiotics, postbi-

otics involve non-viable microbial elements like cell

lysates, microbial fractions, or non-viable microbial cells

to enhance health. ISAPP defines a postbiotic as "a prep-

aration of inanimate microorganisms and/or their compo-

nents that confers a health benefit on the host". The

inactivated form of postbiotics provides better stability,

extending their shelf life (Salminen et al. 2021).

In animal nutrition, these additives are often classi-

fied as "direct-fed microbials" (DFM) (Khan et al. 2016).

DFMs include a variety of microorganisms, such as

yeasts, bacteria, cell fragments, and filtrates (Oetzel

et al. 2007; Elghandour et al. 2015).

Inside the microbiome studies

Given the considerable variability of microbiomes,

determining the optimal sample size and analysis

power remains a challenge (Pollock et al. 2018).

Mixing samples within similar animal groups can offer

a better microbiome representation (Ray et al. 2019).

The sampling technique is a critical point since both

timing and sampling area can affect the results (Zhu et al.

2021). Faecal samples are commonly collected via rectal

exploration or swabs (Weese and Jelinski 2017; Huang

et al. 2020; Massot et al. 2020). For rumen microbiome

studies, the oesophageal probe is commonly used but

has limitations such as contamination by saliva, inability

to select the sampling zone, and collection of only the

liquid fraction (Ramos-Morales et al. 2014). Cannulation

provides access to solid fractions but faces ethical con-

cerns, limiting this approach (Hagey et al. 2022). Buccal

swabs, although fast, have limitations due to buccal

microbiota contamination and the partial missing of spe-

cific rumen bacteria communities. For this reason, they

cannot be used for microbiota characterisation but show

potential as a proxy to evaluate other metabolic aspects

ITALIAN JOURNAL OF ANIMAL SCIENCE 661

(Kittelmann et al. 2015; Young et al. 2020; Miura et al.

2022).

The proper sample storage recommendation for

microbiome studies is to rapidly freeze at least at

−20 C (Song et al. 2016; Knight et al. 2018; Budel et al.

2022; Weinroth et al. 2022). Particularly for rumen sam-

ples, −20 C storage during sampling, freeze-drying,

homogenisation, and storage −80 C are recommended

(Henderson et al. 2015). When rapid freezing is not

available, storage commercial conservation media can

be used for a variable period depending on the sample

(Song et al. 2016). The cell lysis step in DNA extraction is

crucial for high-quality DNA. According to Mott et al.

(2022), bead-beating combined with recommended

methods enhances DNA quantity and quality in rumen

liquor for microbiome analyses (Figure 1).

Sequencing techniques have expanded our ability to

investigate microbiome biodiversity and unknown spe-

cies. With the development of NGS technologies, Illumina

sequencing (sequencing by synthesis, SBS), has become

the gold standard for microbiome studies due to its effi-

ciency and cost-effectiveness. However, Illumina

sequencing typically generates reads that target only

parts of the full 16S gene (maximum read length of

300 bp), leading to lower resolution (McGovern et al.

2018). Third-generation sequencing (TGS) platforms, such

as MinION and PacBio Sequel II, provide full-length 16S

gene reads, offering higher resolution and better taxo-

nomic detail although at a higher cost and lower accur-

acy (Myer et al. 2016; Miura et al. 2022). Consequently,

targeting partial regions of the 16S gene with Illumina

remains the preferred and most common method in

microbiota studies (Santos et al. 2020). The hypervariable

regions commonly used are V3–V4 for bacteria, V6–V8 for

Archaea, and ITS regions 1 and 2 for fungi (Li et al. 2016).

Despite improvements in sequencing depth and read

length, the highest quality results for bacterial taxa iden-

tification are achieved with metagenomic analyses using

TGS technologies (Jovel et al. 2016; Li et al. 2016; Bukin

et al. 2019; Weinroth et al. 2022).

Following sequencing, two critical quality control

steps are essential, removing low-quality sequences and

chimaeras and the removal of host DNA/RNA (Li et al.

2018). A crucial aspect of microbiome studies is differenti-

ating sequences that are classified as unknown. Reads

can be clustered into molecular operational taxonomic

units (OTUs) based on a set dissimilarity threshold, or into

Amplicon Sequence Variants (ASV), which assumes bio-

logical sequences are more likely to be observed repeat-

edly than error-containing ones (Schloss 2021).

The impacts of utilisation of probiotics,

prebiotics and postbiotics in beef cattle diets

Impact of biotics on immunity and general health

In livestock management, dietary shifts are common.

Even when introduced gradually, these adaptation peri-

ods may not fully prevent microbiota imbalances, result-

ing in health declines (Lourenco and Welch 2022).

Figure 1. Mind map of the principal factors to consider during sampling in microbiome studies.

662 S. BETTINI ET AL.

Biotics administration can be a useful strategy to help

maintain gut and microbiota equilibrium thereby

enhancing both animal health and performance and

reducing the need for antibiotics (Donovan et al. 2002).

One mechanism of action is the proliferation of beneficial

microbes that compete with pathogens for epithelium

colonisation. Beneficial bacteria utilise nutrients and

modify the microenvironment, making it hostile to

pathogens (Forestier et al. 2001). Additionally, some bac-

terial strains synthesise molecules with antibacterial

properties such as bacteriocins and organic acids, that

act against the pathogen (Cull et al. 2022). Regarding

non-viable biotics, prebiotics and postbiotics promote a

more stable environment in the rumen and gut, enhanc-

ing the production of key metabolites, such as volatile

fatty acids (VFAs), and promoting microbial growth. In

the rumen, cellulolytic bacteria, lactic acid bacteria (LAB),

and lactate-utilising bacteria (LUB) are particularly stimu-

lated by biotics administration, which can help to reduce

the risk of acidosis and dysbiosis (Retta 2016). Synbiotics,

which combine probiotics and prebiotics, work synergis-

tically to improve microbial diversity and colonisation in

the rumen and gastrointestinal tract. Additionally, postbi-

otic containing bioactive molecules, such as exopolysac-

charides, short-chain fatty acids, enzymes, cell-free

supernatants, cell wall fragments, and bacterial lysates,

contribute to better animal health by stimulating micro-

biota activity, increasing the synthesis of immunoglobu-

lins, increasing macrophage and lymphocyte activity,

inhibiting pathogens, and reinforcing the intestinal bar-

rier (Liu et al. 2023). Furthermore, interactions between

beneficial microflora and pathogens, such as quorum

sensing, can influence the pathogenicity of bacteria

(Medellin-Pe~

na and Griffiths 2009). Indeed the beneficial

effects on rumen and gut health optimise the production

of VFAs, improve digestibility, immunity and reduce

inflammation, collectively improving feed efficiency,

nutrient utilisation, and potential animal growth (Uyeno

et al. 2015; Sousa et al. 2018).

During stressful periods, the administration of

biotics has shown positive results in improving faecal

scores and reducing intestinal pathogens, which

has impacts on animals’ morbidity and mortality

(Tables 1–4). Kelsey and Colpoys (2018) found that a

LAB mix improved performance in calves but had no

significant effects on growth, stress, and health in

female cattle. The authors suggested that the different

results could be attributed to the calves growing

phase which made the use of probiotics meaningful.

Mansilla et al. (2023) observed a significant reduction

of Escherichia coli in cattle faeces using different LAB

strains but no significant effects on performance were

recorded. Sequencing the 16s gene V3–V4 region of

the microbial DNA extracted from the faeces they

found that treated animals showed a greater presence

of the bacterial families Ruminococcaceae,

Lachnospiraceae, and Bifidobacteriaceae (Mansilla et al.

2022). Specifically, Ruminococcaceae and

Lachnospiraceae are key contributors to the break-

down of complex polysaccharides and production of

butyrate, an anti-inflammatory agent and energy

source for intestinal epithelium cells (G

orka et al.

2018). Similarly, Bifidobacteriaceae support gut homeo-

stasis and pathogen resistance, while Lactobacillaceae

promotes a balanced microbiota by regulating intes-

tinal pH (Reuben et al. 2022). McDaniel (2009) found

no health effects in steers fed a LUB probiotic based

on Megasphaera elsdenii when introduced to a high-

grain diet. In the study of Ogunade et al. (2019a) the

metabarcoding analysis of the 16S rRNA gene revealed

no presence of Salmonella in the gut of beef steers

treated with live S. cerevisiae probiotic. The authors

attributed this antimicrobial effect to the mannan oli-

gosaccharides (MOS) produced by S. cerevisiae, which

can act as a high-affinity ligand that binds gram-nega-

tive bacteria. Masanetz et al. (2010) reported improved

performance and gastrointestinal development in

calves supplemented with prebiotic products based

on lactulose or inulin. Fleige et al. (2007) found that a

synbiotic composed of lactulose and Enterococcus fae-

cium administered to calves tended to improve intes-

tinal development and reduce the size of the lymph

follicles due to its role in promoting intestinal health

and in minimising pathogen colonisation.

Furthermore, the authors attributed to lactulose an

influence on apoptosis, a process in the GIT that main-

tains the balance between cell proliferation and death,

ensuring normal structure and function. Ghosh and

Mehla (2012) found improved faecal scores in calves

supplemented with mannan oligosaccharides (MOS)

from Saccharomyces cerevisiae. Magalh~

aes et al. (2008)

observed a tendency to reduce morbidity in calves fed

fructooligosaccharides (FOS). Xiao et al. (2016) and

Alugongo et al. (2017) reported improved gut effi-

ciency, rumen epithelium development, and faecal

scores in calves receiving a postbiotic based on S.

cerevisiae.

In older animals, it is common to observe a decline

in performance and health following transportation.

Several studies have investigated the use of biotics to

prevent these negative impacts. Finck et al. (2014)

administered various biotics derived from S. cerevisiae

to receiving cattle. Both the probiotic and the pre-

biotic reduced rectal temperature and the number of

ITALIAN JOURNAL OF ANIMAL SCIENCE 663

Table 1. Probiotics and their effects.

Substance Dose Effects Animals and duration References

LUB (M. elsdenii) 10–1000 mL/head daily

containing 1.62 10

CFU/mL of M. elsdenii

;

100 mL/head daily

containing 1.62 10

cfu/mL of M. elsdenii

#Lactate; "lactate utilising bacteria

population and pH levels

;

No effect on growth performance

and health

n. 20 steers finishing

phase

n. 3179 steers and heifers

finishing phase

McDaniel

(2009)

110

CFU/animal daily

of M. elsdenii "Longissimus dorsi area and #

marbling scores; no effect on

ADG, feed efficiency, and DMI;

n. 384 steers

42 days

De Aguiar

Veloso et al.

(2021)

110

CFU/animal daily

of M. elsdenii

No effect on ADG, BW, feed

efficiency, ruminal pH, and

fermentations; #DMI and less

time in acidosis condition.

n. 435 steers

fattening phase

Ellerman (2017)

L. plantarum 10 mL/daily (concentration

of 1.8 10

CFU/mL) #pH level; #of protozoa in the

rumen; tendence to "the LAB in

the rumen; no significance effect

on rumen bacteria population;

n. 3 Cannulated heifers Astuti et al.

(2022)

LAB mixture (strains of E.

faecium, L. acidophilus, L.

casei, and L. plantarum)

10 g/head daily "BW, ADG and feed efficiency

; no

effect on growth performance

n. 7 calves

n. 33 heifers

42 days

Kelsey and

Colpoys

(2018)

LAB mixture (L. acidophilus,

L. fermentum and L.

mucosae)

Between 10

and 10

CFU/

animal/daily

No effect on final BW and health;

increase lymphocytes and

neutrophils; #pathogen bacteria

in the faeces.

n. 126 cattle

163 days

Mansilla et al.

(2023)

LAB mixture (L. plantarum,

E.faeciums, C. butyricus)

20, 50, or 100 g daily "Rumen pH level and NH

-N

concentrations; #lactic acid

concentration; no effect on VFA

concentration.

n. 4 heifers cannulated with

acidosis

7 days

Goto et al.

(2016)

LAB

1,2

and LAB/LUB

mix (L.

acidophilus, E. faecium

and Propionibacterium)

CFU/ head daily No effect on DMI, ADG, growth

performance, and carcase

characteristic

No effect on total VFA; tendence to

increase the rumen pH

n. 72 steers

153 days

n. 12 cannulated steers

28 days

Kenney et al.

(2015)

C. butyricum 2.5 10

CFU/kg on DMI "NH

-N, butyrate propionate, and #

acetate rumen concentrations; "

proportion of Firmicutes and #

Bacteroidota; "Christensenellaceae,

Methanobrevibacter,

Oscillospiraceae, Desulfovibrio,

Streptococcus, and C. butyricum; "

Prevotella, Christensenellaceae

Blautia, and M. elsdenii in faeces; #

E. coli and Salmonella.

n. 20 beef steers

n. 40 days

He et al. (2024)

Active Chordicoccus

furentiruminis, Prevotella

albensis, and Succinivibrio

dextrinosolvens (native

rumen microbes)

5 g head daily #CH

yield (g/kg of DMI) by 20%;

last finishing period "ADG

(p¼0.02) and DMI (p¼0.10); "

unclassified Lactobacillus,

unclassified Clostridia, Prevotella

multisaccharivorax, unclassified

Erysipelotrichia, unclassified

Saccharibacteria genera incertae

sedis, and Prevotella copri; #

Anaeroplasma abactoclasticum,

unclassified Bacteroidaceae,

unclassified Clostridiales, and

unclassified Bacteroidetes.

n. 80 beef cattle

n. 124 ±27 days

Pittaluga et al.

(2023)

Active dry yeast S. cerevisiae 15 g/ head daily "relative abundance

Ruminococcaceae, aerovorax; "

Christensenellaceae R-7 group and

Candidatus saccharimonas and

Bacteroidales BS11 correlated to

amino acid and energy

metabolism; #Salmonella

presence

n. 8 rumen-cannulated

steers;

25 days

Ogunade et al.

(2019a)

15 g/ head daily -"Ruminococcus albus, R.

champanellensis, R. bromii, R.

obeum, M. elsdenii, Desulfovibrio

desulfuricans, D. vulgaris; "

carbohydrate-active enzymes in

the rumen.

n. 8 rumen-cannulated

steers;

25 days

Ogunade et al.

(2019b)

(continued)

664 S. BETTINI ET AL.

cattle requiring more than one antibiotic treatment.

The synbiotic, a mix of the previous biotics, showed

similar results on antibiotic treatment needs but it did

not have positive effects on morbidity. However, all

biotics reduced numerically animals’ mortality. The

benefits on health derive from the MOS ability to

reduce pathogens and the stimulation of antimannan

antibodies. He et al. (2024) found an enhanced health

status in cattle treated with Clostridium butyricum and

a reduced concentration of pathogens in the intestine,

particularly Salmonella and E. coli. The authors justified

this result with an increased SCFA content in faeces. That

could be due to the increased population of C. butyricum,

which can improve the production of SCFA and affect

the pH, making the environment hostile to pathogens.

He et al. (2024) found that C. butyricum administration

improved the concentration of NH

–N, propionate and

butyrate and decreased the acetate:propionate ratio

Table 1. Continued.

Substance Dose Effects Animals and duration References

510

CFU/ head daily "DMI; #antibiotic treatment needs;

greater serum concentrations of

IFN-c; no effect on BW and ADG.

n. 60 cattle

56 days

Finck et al.

(2014)

0.1% on DM "pH level and acetate and

propionate production in the

rumen; #lactate and propionate

acetate ratio; #S. bovis population

and "M. elsdenii and S.

ruminantium.

n. 6 steers cannulated

30 days

Zhang et al.

(2022)

1 g/head daily (8.0 10

CFU/g) "The DMI; #corticotropin-releasing

hormone and "ghrelin O-acyl

transferase, Cu and Zn in the

blood; no effect on final BW, ADG,

feed efficiency, or rumen fatty

acids concentration.

n. 20 bulls

100 days

Luan et al.

(2023)

0.8 g/head daily "BW, DMI, ADG, carcase weight; "

% blood triglycerides and free

fatty acids; "meat tenderness.

n. 45 bulls

112 days

Geng et al.

(2016)

0.8 g/head daily No effect on rumen pH, no effect on

the molar portion of VFA and

total production; "% palmitoleic

acid (C16:1n7) in meat lipid

profile.

n. 45 bulls

112 days

Geng et al.

(2018)

Superscript numbers indicate an exclusive effect obtained on a specific group of animals when multiple animal categories or biotics products were used

in the same study. ADG: average daily gain; BW: body weight; DM: dry matter; DMI: dry matter intake; VFA: volatile fatty acids, LAB: lactic acid bacteria;

LUB: lactate utilising bacteria; #: decrease; ": increase.

Table 2. Prebiotics and their effects.

Substance Dose Effects Animals and duration References

Alfa-amylase from A. oryzae

and S. cerevisiae

The activity of 950

dextrinizing units/kg

of DM

"ADG, DMI, BW, and carcase weight

1,2

; no

effect on growth performance

n. 120 steers

112 days

;

n. 96 heifers

70–90 days

n. 64 steers

56 days (DMI limited)

Tricarico et al.

(2008)

Enzymatic extract from A.

oryzae and Trichoderma

viride

10 g/head daily "ADG, DM apparent digestibility, and carcase

characteristics.

n. 36 bulls

84 days

Neumann et al.

(2018)

Mannan

oligosaccharides (MOS)

4 g/head daily "ADG, DMI, feed efficiency, and faecal score;

#faecal Coliform counts.

n. 36 Calves

55 days

Ghosh and

Mehla

(2012)

S. cerevisiae cell wall

fragments

5 g/ head daily "DMI; #antibiotic treatment needs; no effect

on BW and ADG.

n. 60

56 days

Finck et al.

(2014)

Fructooligosaccharides (FOS) 2% inulin on DM No effect on DMI; "feed efficiency, ADG, and

rumen development.

N. 42 calves

140 days

Masanetz et al.

(2010)

Lactulose 2% lactulose on DM #DMI; "GIT development; no effect on

growth performance.

N. 42 calves

140 days

Masanetz et al.

(2010)

Niacin 1000 mg/head daily #Relative abundance Fibrobacter spp,

Ruminococcus spp, S. ruminantium, and

Succinivibrio; "relative abundance of

Butyrivibrio fibrisolvens and Roseburia "

butyrate production; "Carbohydrate lipid

and protein digestion and absorption;

"intramuscular fat;

N. 16 steers

120 days

Yang et al.

(2024)

Superscript numbers indicate an exclusive effect obtained on a specific group of animals when multiple animal categories were used in the same study.

ADG: average daily gain; BW: body weight; DM: dry matter; DMI: dry matter intake; GIT: gastrointestinal tract; #: decrease; ": increase.

ITALIAN JOURNAL OF ANIMAL SCIENCE 665

which could enhance both protein and energy supply.

Through metabarcoding, they also found a reduction of

Prevotella concentration in the treated group. The

decrease in the proportion of Prevotella could be attribu-

ted to the higher rumen pH. This increase in pH might be

linked to Desulfovibrio, a lactate-utilising bacterium. The

proportion of Desulfovibrio increased with the addition of

C. butyricum. Moreover, microbial diversity increased in

the treated group. This was confirmed by the increased

Firmicutes to Bacteroidota (F/B) ratio, which is an indica-

tor of the microbiota efficiency energy absorption.

Colombo et al. (2021) found lower mortality and

improved immunity in cattle treated upon arrival with a

synbiotic based on a yeast-derived prebiotic and Bacillus

subtilis, compared to cattle receiving antibiotics.

Moreover, cattle treated with the synbiotic demonstrated

Table 3. Synbiotics and their effects.

Substance Dose Effects Animals and duration References

Lactulose þE. faecium 3% lactulose on DM þ10

CFU E. faecium kg

of DM

"DMI and GIT epithelium

development; Increasing dose

of lactulose tended (p>0.1) to

increase ADG.

n. 42 calves

days approx. 135

Fleige et al.

(2007)

S. cerevisiae extract and active dry

yeast þE. lactis, B.

licheniformis and B. subtilis

fermentation

product þchromium

propionate

6–8% of DM No effect on BW, DMI, and feed

efficiency; no effect on

mortality and antibiotic

treatment needs; no effect on

carcase quality

n. 240 crossbreed cattle

21 or 42 days post transport

Homolka et al.

(2023)

Yeast derived prebiotic þB.

subtilis þL. plantarum

18 g prebiotic þ28 g

probiotic/ head daily "DMI and ADG for the first

3 weeks; no effect on BW and

overall ADG; #number of

second antibiotic treatment

and mortality; M. haemolytica

antibodies.

n. 256 steers

46 days post 2–8 h of

transport

Colombo et al.

(2021)

Active dried S. cerevisiae þ

Mannan Oligosaccharides þ

Selenium

5 g/head daily of active

form, 10 g/head daily of

MOS, and 3 mg/head

daily of Selenium

"Final BW and ADG 0–30 days;

no effect on carcase weight; "

nutrients digestibility; #bovine

respiratory diseases and relapse

rates; no effect on mortality; "

serum bactericidal activity and

the immunity response; no

significant effect on

c-interferon levels and

inflammatory status.

n. 1036

n. 186 days post transport

Grossi et al.

(2021)

Active dry and culture of S.

cerevisiae "DMI; #antibiotic treatment

needs; no effect on BW

and ADG.

n. 60

56 days

Finck et al.

(2014)

ADG ¼average daily gain; BW ¼body weight; DM ¼dry matter; DMI¼dry matter intake; GIT ¼gastrointestinal tract; # ¼ decrease; " ¼ increase.

Table 4. Postbiotics and their effects.

Substance Dose Effect

Animal and

duration References

S. cerevisiae fermentation

products (SCFP)

1 g/L milk þ0.5–1% in the

starter "Butyrate rumen;

"Butyrivibrio and #Prevotella; "

development GIT epithelium.

n. 30 Calves

30 days

Xiao et al.

(2016)

1 g/L milk þ0.5–1% in the

starter #Diarrhoea episodes; No effect on growth

performance.

n. 60 Calves

30 days

Alugongo et al.

(2017)

2% of DM No effect on growth performance, DMI;

#mortality, the risk of diseases, and the

use of antibiotics. No effects on the

number of antibodies and functional

neutrophils.

n. 512 calves

70 days

Magalh~

aes

et al. (2008)

50 g/head daily No effect on BW, DMI, ADG, and carcase

weight; "% blood triglycerides and

meat tenderness.

n. 45 bulls

112 days

Geng et al.

(2016)

50 g/head daily No effect on rumen pH, no effect on total

VFA, #valerate molar percentage, "

acetate molar percentage, and acetate

to propionate ratio.

n. 45 bulls

112 days

Geng et al.

(2018)

Lactobacillus fermentation

product

5 mL/head daily "DMI, ADG, and rumen butyrate; #rumen

propionate; no effect on feed efficiency

and DM digestibility.

n. 160 steers

42 days

Hall et al.

(2018)

ADG ¼average daily gain; BW ¼body weight; DM ¼dry matter, DMI ¼dry matter intake; GIT¼gastrointestinal tract; VFA ¼volatile fatty acids;

# ¼ decrease; " ¼ increase.

666 S. BETTINI ET AL.

a reduced need for a second antibiotic treatment. The

authors attributed the results to the synergistic anti-

inflammatory and immune-stimulating effects of yeast-

derived beta-glucans and MOS, as well as the ability of B.

subtilis to stimulate the synthesis of immunoglobulins

and Th1 cytokines. Grossi et al. (2021) found reduced

mortality and morbidity rates, with a significant reduction

in the incidence of BRD, by adding to the diet of trans-

ported cattle a synbiotic based on S. cerevisiae, MOS, and

organic selenium. In contrast, in a study by Homolka

et al. (2023), no difference in health benefits was

observed in cattle transported and treated with a yeast-

bacteria synbiotic when compared to animals receiving

antibiotics. Biotics can modulate the immune system by

stimulating the activity of immune cells and the produc-

tion of immunoglobulins and cytokines. In addition, they

can stimulate the c-interferon production and inflamma-

tory status in ruminants (Reuben et al. 2022; Liu et al.

2023). It must be said that differences in results obtained

in these studies can be attributed to various factors influ-

encing the risk of health decline, including initial disease

risk upon arrival, method of administration, type of

biotics used, and presence of antibiotics in the feed.

In conclusion, biotics are especially beneficial dur-

ing stressful periods, dietary shifts, and environment

adaptation. Their positive effects on the intestinal and

rumen environment and development, and the reduc-

tion of pathogenic bacteria are crucial for maintaining

animal performance. However, due to the complex

variables that can influence biotics effects, establishing

the most efficacy product is still a challenge.

Impact of biotics on the ruminal ecosystem

Ruminal ecosystem

Ruminants have a complex stomach with four compart-

ments: rumen, reticulum, omasum, and abomasum. The

rumen is an anaerobic fermentation chamber with

temperatures around 39 C and a pH between 5.6 and

7.0, highly influenced by diet (Membrive 2016). In beef

cattle, high-grain diets decrease rumen pH often below

5.6 after feeding, leading to acidosis and affecting micro-

bial activity, rumen function, and cattle health with reper-

cussions on feed intake and diet digestibility

compromising performance (Nagaraja and Titgemeyer

2007). The rumen microbiota breaks down ingesta into

nutrients and maintaining optimal rumen conditions is

essential for animal productivity (Ahlawat et al. 2021).

The rumen microbiota includes bacteria, archaea, fungi,

protozoa, and bacteriophages (Agarwal et al. 2015).

Bacteria represent the majority of live cells in the rumen,

comprising between 40% and 50% of the total mass

(Agarwal et al. 2015). Biotics can significantly alter the

microbiota, particularly bacteria involved in carbohydrate

and lactic acid metabolism, affecting rumen pH and

digestibility (Zhou et al. 2015; Bandarupalli and St-Pierre

2023). The major mechanism by which biotics enhance

nutrient digestibility and feed intake is likely attributable

to their support of the growth of ruminal cellulolytic bac-

teria and those involved in lactate metabolism. This helps

prevent ruminal acidosis while stimulating bacterial activ-

ity and increasing the production of volatile fatty acids

(VFAs) that can contribute to improve beef performance

(Reuben et al. 2022; Liu et al. 2023).

Impact of biotics on rumen microbiota and

fermentations products

Changes in microbiota composition can modulate the

presence of acids in the rumen. Acetate, butyrate, and

propionate are the principal volatile fatty acids (VFA) pro-

duced by bacterial fermentation and they play an essen-

tial role in satisfying the ruminants’ nutritional

requirements and stabilise the rumen environment and

thus promoting animal performance. Zhang et al. (2022),

during an in vitro ruminal fermentation trial with different

doses of S. cerevisiae, found a higher acetate and propi-

onate production and a lower acetate:propionate ratio in

treated samples. The higher acetate concentration

observed with yeast administration could be due do a

more favourable environment for the growth of cellulo-

lytic. These bacteria are more efficient in acetate produc-

tion explaining the change in volatile fatty acids

production (Pinloche et al. 2013). In the in vivo trials, they

found a reduction of Streptococcus bovis and an increased

presence of M. elsdenii and Selenomonas ruminantium,

concurrently to a higher pH and a lower lactate rumen

concentration, which reduces the risk of acidosis and pre-

vents negative repercussions on performance and health.

Ogunade et al. (2019a), using both metabarcoding and

metabolomics approaches, evaluated the impact of a live

S. cerevisiae probiotic on rumen microbiota composition

and functionality in beef steers. They identified correla-

tions between changes in the metabolomic rumen profile

and specific microbial species, including Candidatus

saccharimonas, Christensenellaceae R-7 group, and

Bacteroidales BS11 bacterium linked to amino acid metab-

olism and reduced ammonia levels. The probiotic

enhanced microbial protein synthesis, likely due to

improved carbohydrate metabolism and cellulose deg-

radation, as evidenced by increased acetate levels and

cellulose-degrading bacteria (Ruminococcaceae). They

identified unique OTU in the untreated animals belong-

ing to aerobic (Comamonas and Arcticibacter), ruminal

ITALIAN JOURNAL OF ANIMAL SCIENCE 667

lactic acid producers (Lactococcus), saccharolytic

(Mogibacterium), and amino acid fermenters

(Proteiniclasticum). Additionally, they found a higher rela-

tive abundance of Anerovorax in the treated group that

supports the improved anaerobic status of the rumen,

facilitated by the oxygen-scavenging activity of live yeast.

They did not find any effect on the lactate production. In

a similar work, they use metagenomic to evaluate the

effect of S. cerevisiae probiotic on the rumen microbiome.

The authors found an increase in abundance of carbohy-

drate-fermenting bacteria (such as Ruminococcus albus,

Ruminococcus champanellensis, Ruminococcus bromii, and

Ruminococcus obeum) and lactate-utilising bacteria (such

as M. elsdenii, Desulfovibrio desulfuricans, and

Desulfovibrio vulgaris). Additionally, they found enhanced

pathways related to carbohydrates and amino acids.

Astuti et al. (2022) observed higher propionate and lower

acetate levels in cannulated beef cattle fed Lactobacillus

plantarum and a higher presence of LAB. However, no

significant changes were observed in the total number of

bacteria. The shifts to propionate production reduce H

availability for methane production which contributes to

energy lost. Reducing methane production will increase

energy availability for the animal supporting the perform-

ance. A meta-analysis by Susanto et al. (2023) indicated

that M. elsdenii supplementation increases propionate

production and reduces lactic acid and acetate concen-

trations in the rumen due to microbiota modulation. Hall

et al. (2018) found decreased propionate and increased

butyrate levels in steers fed a Lactobacillus postbiotic.

Propionate has an effect on satiety, and therefore its

reduction can increase feed intake in certain cases. Geng

et al. (2018) observed a higher acetate:propionate ratio in

bulls fed with a synbiotic derived from S. cerevisiae. Xiao

et al. (2016) reported increased levels of butyrate treated

with an S. cerevisiae postbiotic. Through metabarcoding

of the 16S rRNA gene’s V3 region, they observed

increased bacterial richness and a lower abundance of

the Prevotella genus and a higher abundance of the

genus Butyrivibrio. Prevotella mainly produces acetate

and propionate, thus its reduction along with the

increase of the genus Butyrivibrio contributes to elevated

butyrate levels in the rumen of treated calves. According

to the authors, butyrate plays a crucial role in rumen pap-

illae development providing energy for epithelial cells.

Additionally, the ability of postbiotic bioactive com-

pounds to bind pathogens may explain the improved

rumen morphology of treated animals.

The VFA modulation influences GHG emissions

since the Archaea population present in the rumen

can produce methane, a climate-altering gas (Haque

2018). VFA production affects substrates for Archaea,

with propionate reducing H

presence in the rumen

and acetate production releasing H

. The presence of

levels can affect methane emissions (Beauchemin

et al. 2020). Biotics administration can affect methane

emissions by altering fermentation products, although

studies on beef cattle remain scarce. Jeyanathan et al.

(2016) found a 13% reduction in vitro CH

emissions

with Lactobacillus pentosus in sheep, attributed to

changes in the microbial community. A later study on

cows did not replicate the same results (Jeyanathan

et al. 2019). Chen et al. (2020) found that several pro-

biotics derived from propionic acid bacteria probiotic

reduced CH

synthesis in vitro, linked to specific bac-

terial groups’ growth and metabolic shifts. A meta-

analysis by Darabighane et al. (2019) concluded that S.

cerevisiae supplementation does not affect CH

emis-

sions in beef and dairy cows. Susanto et al. (2023)

reported that M. elsdenii reduces methane by lowering

hydrogen and increasing propionate production, align-

ing with Ncho et al. (2024), who found no overall

effect of probiotics but observed significant methane

emissions reductions when combining acetogenic and

propionate-producing bacteria.

Impact of biotics on rumen pH

Several studies have evaluated the impacts of biotics

administration on the ruminal ecosystem (Tables 1–4).

These nutritional strategies can enhance animal per-

formance and health by promoting a better rumen

environment, increasing fibre digestion, and support-

ing the proliferation of targeted microbial species

(Uyeno et al. 2015). In beef cattle, the administration

of biotics based on yeast, LAB, and LUB has been

shown to prevent acidosis (Nagpal et al. 2015).

McDaniel (2009) observed a reduction in low rumen

pH occurrences in steers treated with a LUB probiotic

based on M. elsdenii, corresponding to higher percen-

tages of LUB and decreased lactate concentration.

Ellerman (2017) did not find significant differences in

rumen pH or lactate percentage with the same pro-

biotic product. Both studies indicated that LUB probi-

otics help prevent rumen acidosis during diet

transitions modulating the microbiota. M. elsdenii

administration modified microbiota composition and

fermentation product increasing the presence of LUB

and protozoa and decreasing the percentage of S.

bovis (Arik et al. 2019). Goto et al. (2016) found that

administering a LAB mixture to cattle fed with a high-

grain diet, increases pH levels reducing lactic acid con-

centration. In contrast, Astuti et al. (2022) observed a

significant pH reduction with Lactobacillus plantarum

administration to cannulated beef cattle. However, the

668 S. BETTINI ET AL.

authors reported that the pH values were always higher

than 6.2, which was considered an acceptable range.

Through the characterisation of bacterial populations

and their fermentation products, they observed

increased total VFA production and fibrinolytic bacteria

abundance, such as Ruminococcus albus, which are clear

indicators of effective ruminal activity. Ensuring the

presence of LAB and their metabolites, stimulates the

growth of LUB, enhancing the host microbiota’s ability

to maintain optimal rumen pH (Chiquette 1995).

Similarly, yeast probiotics when administered in the

diet can affect rumen pH (Tables 1–4). One potential

mechanism is their superior sugar affinity, which

reduces substrates for lactate synthesis. Additionally,

yeasts stimulate the growth of lactate-utilising bacteria

through direct microbial feeding (Chaucheyras-Durand

et al. 2012; Ding et al. 2014), and promote protozoa

that engulf sugar particles, slowing fermentation

(Retta 2016). Zhang et al. (2022) observed increased

rumen pH and reduced lactic acid levels in cannulated

steers fed with a probiotic based on S. cerevisiae.

Quantitative PCR identified a reduction in

Streptococcus bovis and an increase in M. elsdenii and

S. ruminantium, likely due to an increase in fibre-

degrading bacteria (Zhu et al. 2021). A study by Geng

et al. (2018) found similar results in bulls treated with

a dried probiotic or a synbiotic based on S. cerevisiae.

In the study of Ogunade et al. (2019b), the administra-

tion of S. cerevisiae probiotic to steers improved

rumen function. They found enriched genes in treated

rumen bacteria involved in carbohydrate, energy, and

amino acid metabolism simultaneously to increase

carbohydrate-active enzymes.

In conclusion, biotics based on LAB and LUB, due

to their key roles in lactate metabolism, and yeasts,

for their role in enhancing fibre degradation and

improving pH, have shown promising results.

However, due to the lack of studies comparing differ-

ent categories of biotics, it is not possible to defini-

tively determine the most effective type or category.

Impact of biotics on nutrient digestibility

Biotics and their metabolites, mostly yeast, stimulate

rumen fungi enhancing their colonisation and releas-

ing fermentable carbohydrates for cellulolytic bacteria

growth. Yeast probiotics sequester oxygen in the

rumen, promoting an anaerobic environment (Marden

et al. 2008). This and the higher pH promote a favour-

able habitat for fibre-degrading bacteria, linked to a

higher nutrient digestibility (Chaucheyras-Durand et al.

2012; Sousa et al. 2018). Ding et al. (2014) found

increased dry matter (DM) and neutral detergent fibre

(NDF) digestibility in steers fed with S. cerevisiae probi-

otics. Rumen fluid microbiota revealed higher amounts

of fungi and protozoa, with increased copies of S.

ruminantium and fewer copies of Ruminococcs amylo-

philus, attributed to S. cerevisiae’s ability to compete

with starch-degrading bacteria and stimulate the

growth of LUB. The increase in digestibility could be

due to a better rumen environment, especially rumen

pH, and the stimulation effect on fibre degrading bac-

teria. Ogunade et al. (2019b) reveal by metagenomic

analyses important changes after the administration of

an S. cerevisiae probiotic in the ability of the micro-

biome to enhance carbohydrate and cellulose degrad-

ation. Zapata et al. (2021), noticed reduced Clostridium

amilophilus concentrations and improved DM, N, and

energy digestibility in animals fed with a synbiotic

based on S. cerevisiae, MOS, and beta-glucans.

Neumann et al. (2018) reported improved DM digest-

ibility in bulls fed a yeast-based prebiotic. Grossi et al.

(2021) found a decrease in the percentage of NDF,

acid detergent fibre (ADF), and starch in the faeces of

treated animals with a synbiotic based on S. cerevisiae,

MOS, and selenium. The authors justified this result

with the increased gastrointestinal digestibility. Hall

et al. (2018) found increased dry matter intake (DMI)

and average daily gain (ADG) but no effects on DM

digestibility in steers fed a postbiotic based on

Lactobacillus.

Impact of biotics on growth performance

Key indicators of beef production are tied to the ani-

mals’ muscle growth potential. Growth is assessed

using ADG, body weight (BW), and carcase yield. ADG

reflects daily weight gain, indicating growth rate and

health status, while BW is crucial for evaluating devel-

opment and calculating carcase yield, the proportion

of muscle processable into the meat (Hoz

akov

a 2020).

Numerous studies have evaluated the effect of

biotics on the growth performance of beef cattle.

These products in certain cases can improve ADG, BW,

DMI, and feed efficiency due to their effects on nutri-

ent digestibility, health, rumen, and gut microbiota

stimulation explained in the previous chapters (Tables

1–4). Luan et al. (2023) found that bulls receiving

active dried cells of S. cerevisiae in the diet showed

increased DMI but no significant effects on perform-

ance. The probiotic was shown to elevate levels of

ghrelin O-acyl transferase, a regulator of satiety and,

consequently, DMI. However, the exact mechanism

behind this increase remains unclear. Additionally, the

rise in fibre-degrading bacteria may help improve fibre

ITALIAN JOURNAL OF ANIMAL SCIENCE 669

digestion, contributing to enhanced fibre passage

rates. Tricarico et al. (2008) reported improved per-

formance traits in calves, steers, and heifers on a high-

concentrate diet supplemented with prebiotic feeds

based on S. cerevisiae and/or Aspergillus oryzae.

Additionally, Geng et al. (2016) added to feed of fin-

ishing bulls a probiotic or a synbiotic based on S. cere-

visiae. Only the active form showed significant positive

results on BW, DMI, ADG, carcase yield, and increased

fat content in the meat compared to untreated ani-

mals. There was also a tendency to improve perform-

ance in the bulls treated with the synbiotic. The

authors justified these results by the increase of DMI

and changes in fat metabolism. The need for integra-

tion of metagenomics in studies on rumen microbiota

manipulation through potential biotics in beef cattle is

highlighted in a recent study by Yang et al. (2024).

Similar to Geng et al. (2016), they observed improve-

ments in intermuscular fat in cattle treated with

1,000 mg/d of niacin. Niacin could be categorised as a

prebiotic due to its role in stimulating the microbiota

(Bedani et al. 2024). Through metagenomic analysis of

the rumen microbiome, they identified microbial taxa

and functional pathways influenced by dietary niacin.

They also examined correlations between niacin-

modulated microbial species and the functional

capacities of the rumen microbiome, specifically in

relation to intramuscular fat (IMF) content and nutrient

metabolism. Nine microbial species were enriched nia-

cin-treated group and positively correlated with IMF,

while six species were decreased and negatively corre-

lated with IMF. Additionally, they found a decrease in

fibre-degrading bacteria, such as Fibrobacter spp. and

Ruminococcus spp., concomitant with an increase in

butyrate-producing bacteria like Butyrivibrio fibrisolvens

and Roseburia intestinalis. Additionally, they found an

increase in Succinivibrio species and S. ruminantium,

which improved dietary protein utilisation. Moreover,

they found a decrease in Methanocorpusculum, a

genus associated with methane emissions, in niacin-

treated animals, which, combined with an increased

ability to utilise carbohydrates and improved nutrient

digestion, could have contributed to a reduction in

methane production. These results suggest that niacin

supplementation modifies the microbial population,

enhancing its capacity for nutrient digestion and

absorption, which is beneficial for meat production

and IMF accumulation. Also, Grossi et al. (2021) found

performance traits increased in newly feedlot cattle

fed with a synbiotic based on S. cerevisiae probiotic,

MOS, and selenium. Contrary, Finck et al. (2014) found

significantly increased DMI but no effect on BW or

ADG in receiving cattle fed with biotics based on S.

cerevisiae. Similarly, Homolka et al. (2023) did not find

any positive result in BW, ADG, feed efficiency, and

DMI administering a synbiotic based on S. cerevisiae

probiotic, Enterococcus and Bacillus prebiotic, and

chromium propionate to newly feedlot cattle. Similar

results have been found by Colombo et al. (2021) in

steers treated with synbiotics based on yeast ingre-

dients and Bacillus probiotics. Magalh~

aes et al. (2008)

observed no significant effect on growth performance

and DMI in calves administered a synbiotic based on

S. cerevisiae. These results are consistent with studies

by Xiao et al. (2016) and Alugongo et al. (2017), which

found no treatment effects on BW, ADG, or feed effi-

ciency in calves treated with a postbiotic based on S.

cerevisiae. Notably, the active form shows more prom-

ising results in improving performance during the fin-

ishing phase of beef livestock due to its role in

structural carbohydrate digestion (Torres et al. 2022).

According to Ghazanfar et al. (2017), yeast-based

biotics tend to show better results in adult animals,

while bacteria-based biotics are more effective in

young animals due to their role in improving ruminal

and intestinal development and immunity systems.

McDaniel (2009) found no effects on the growth per-

formance of 3179 steers and heifers receiving different

doses of LUB in the finishing phase, a finding sup-

ported also by De Aguiar Veloso et al. (2021) and

Ellerman (2017). Kelsey and Colpoys (2018) observed

increments in BW, ADG, and better feed conversion

ratios in calves receiving LAB mix probiotics, but no

effects were seen in older animals. Similarly, Mansilla

et al. (2023) reported no effects on growth perform-

ance in cattle administered an LAB mix, and Kenney

et al. (2015) concluded that LAB and LAB/LUB mix pro-

biotics do not improve growth performance in beef

cattle. Pittaluga et al. (2023) found increased ADG in

beef cattle fed with native rumen microbes

(Chordicoccus furentiruminis, Prevotella albensis, and

Succinivibrio dextrinosolvens). They justified by a higher

feed efficiency related to changes in microbiota com-

position. The unclassified Clostridia, P. copri, P. multi-

saccharivorax, and unclassified Saccharibacteria genera

incertae sedis. These bacteria can utilise multiple poly-

saccharides and their increase can improve the rumen

environment, stabilising the pH and promoting VFA

production. Moreover, they found a reduction in CH

emission that is associated with a higher feed effi-

ciency. Masanetz et al. (2010) found no effects on

growth performance in calves given a lactulose-based

prebiotic, contrarily. Fleige et al. (2007) observed

increased DMI and a tendency for higher ADG in

670 S. BETTINI ET AL.

calves receiving a synbiotic based on lactulose and E.

faecium, suggesting that the interaction between pre-

biotic and probiotic could be the cause of the differ-

ent results obtained. Hall et al. (2018) reported

increased DMI and ADG in steers supplied with a post-

biotic based on Lactobacillus fermentation products,

but no impact on feed efficiency.

Feed efficiency is commonly used to measure the

conversion of feed consumption into animal products

and is correlated with animal performance and dry

matter intake. Numerous factors influence DMI, like

diet energy content, forage and concentrate ratio,

gastrointestinal tract passage rate, and health condi-

tions. Consequently, it is difficult to identify a single

mechanism of action for DMI modification following

biotics supplementation. Potential mechanisms of

action include improved forage retention time in the

rumen, increased NDF digestibility stimulation micro-

biota, providing enzymes, and altered satiety signals

(Boyd et al. 2011; Ding et al. 2014; Retta 2016). Luan

et al. (2023) observed increased DMI and higher blood

ghrelin levels in bulls receiving S. cerevisiae active dry

yeast, although no effects on performance were

recorded. They attributed the increased DMI to circu-

lating ghrelin, a hormone that influences eating dur-

ation and meal size (Wertz-Lutz et al. 2006). Hall et al.

(2018) found decreased propionate production and

increased DMI in steers receiving a prebiotic based on

Lactobacillus. Geng et al. (2018) reported a higher ace-

tate:propionate ratio and increased DMI with a ten-

dency to improve feed efficiency in animals receiving

a synbiotic based on S. cerevisiae. Higher propionate

levels can reduce feed intake in steers by altering

meal size and intermeal intervals; however, the exact

mechanisms remain unclear, necessitating further

research (Allen 2000; Maldini and Allen 2018).

According to Cole et al. (1992), the positive effects

of biotics on growth performance are generally

observed when the health of the animals is compro-

mised. This is further supported by the observation

that these additives are most beneficial in young ani-

mals or those subjected to stressors such as transport,

environmental changes, or diet changes, which make

them more susceptible to metabolic disorders and dis-

ease (Uyeno et al. 2015). Kelsey and Colpoys (2018)

found that reducing stress through E. faecium and

Lactobacillus probiotics administration in calves

resulted in increased ADG, while the same treatment

did not affect heifers due to their stronger immune

systems and fewer stress factors. Similarly, Mansilla

et al. (2023) attributed the trend of increases in BW

and ADG of treated animals to the stimulation of the

immune system and beneficial microflora, promoting a

healthier gut environment and relative VFA produc-

tion. Susanto et al. (2023), evaluating the effects of

LUB supplementation in beef cattle, concluded that

performance improvements in treated animals were

due to a healthier gastrointestinal system.

Conclusions and future perspectives

In conclusion, the administration of biotics represents

a promising approach to improving performance and

health in beef cattle. The choice of the most appropri-

ate type of biotic is crucial to maximise these benefits.

Probiotic bacteria, particularly effective in modulating

gastrointestinal microbiota and ruminal fermentation,

play a crucial role in promoting growth in young ani-

mals and helping adults adapt to dietary changes and

stress events. Yeast probiotics improve digestibility

and gastrointestinal health, due to their role in the

fibre digestive process and pH regulation. Prebiotics

improve nutrient digestibility and gut health especially

in young ruminants, by stimulating the growth of the

host’s microbiota. Synbiotics offer a synergistic effect

that facilitates the implantation of probiotics in the

gastrointestinal tract. Postbiotics, despite limited

research, seem to show a higher stability due to the

inactivation of the microorganism with similar benefits

of viable forms.

However, the current scarcity of studies directly

comparing different categories of biotics in the same

experimental setting makes it difficult to evaluate the

most effective. Moreover, as underlined by the limited

studies currently available, the use of -omics technolo-

gies enables a more in-depth investigation of the rela-

tionships between the microbiota, nutrition, and

performance in beef cattle. Looking to the future,

advanced -omics technologies are crucial to under-

standing the interactions between biotics and micro-

biota. The initial section of this review may provide a

valuable introduction to the -omics approach in this

field. There is an urgent need for standardised and

comprehensive studies, particularly in beef cattle as

compared to dairy cattle. Furthermore, the integration

of nutrition and metagenomics approaches holds

promise for significantly enhancing the sustainable

and effective breeding of beef cattle.

Acknowledgements

The authors confirm that they have no conflicts of interest

to disclose.

ITALIAN JOURNAL OF ANIMAL SCIENCE 671

Author contributions

Stefano Bettini: Conceptualisation; data curation; bibliog-

raphy source; methodology; validation; visualisation; writing

– original draft; Francesco Perini and Daniele Colombi:

Conceptualisation; investigation; methodology; supervision;

writing – review and editing; Massimo Trabalza-Marinucci

and Emiliano Lasagna: Conceptualisation; funding acquisi-

tion; project administration; supervision; writing – review

and editing.

Disclosure statement

The authors declare that there are no conflicts of interest.

Ethics statement

The data for this review were sourced from published scien-

tific papers, so Animal Care and Use Committee approval

was not required.

ORCID

Stefano Bettini http://orcid.org/0009-0005-5665-0007

Francesco Perini http://orcid.org/0000-0003-2235-3926

Daniele Colombi http://orcid.org/0000-0001-5167-0459

Massimo Trabalza-Marinucci http://orcid.org/0000-0001-

9082-0106

Emiliano Lasagna http://orcid.org/0000-0003-2725-2921

Data availability statement

None of the data were deposited in an official repository.

The data that support the findings presented in this study

are available from the corresponding author upon reason-

able request.

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A Meta-analysis of probiotic interventions to mitigate ruminal methane emissions in cattle: implications for sustainable livestock farming

Article

Full-text available

May 2024
ANIMAL

In recent years, the significant impact of ruminants on methane emissions has garnered international attention. While dietary strategies have been implemented to solve this issue, probiotics gained the attention of researchers due to their sustainability. However, it is challenging to ascertain their effectiveness as an extensive range of strains and doses have been reported in the literature. Hence, the objective of this experiment was to perform a meta-analysis of probiotic interventions aiming to reduce ruminal methane emissions from cattle. From 362 articles retrieved from scientific databases, 85 articles were assessed independently by 2 reviewers, and 20 articles representing 49 comparisons were found eligible for meta-analysis. In each study, data such as mean, standard deviation, and sample sizes of both the control and probiotic intervention groups were extracted. The outcomes of interest were methane emission, methane yield, and methane intensity. For the meta-analysis, effect sizes were pooled using a fixed effect or a random effect model depending on the heterogeneity. Afterward, sensitivity analyses were conducted to confirm the robustness of the findings. Overall pooled standardized mean differences (SMD) with their confidence intervals (CIs) did not detect significant differences in methane emission (SMD = -0.04; 95% CI = -0.18 to 0.11; p = 0.632), methane yield (SMD = -0.08; 95% CI = -0.24 to 0.07; p = 0.291), and methane intensity (SMD = -0.22; 95% CI = -0.50 to 0.07; p = 0.129) between cattle supplemented with probiotics and the control group. However, subgroup analyses revealed that multiple-strain bacterial probiotics (SMD = -0.36; 95% CI = -0.62 to -0.11; p = 0.005), specifically the combination of bacteria involved in reductive acetogenesis and propionate production (SMD = -0.71; 95% CI = -1.04 to -0.36; p = 0.001), emerged as better interventions. Likewise, crossbreeds (SMD = -0.48; 95% CI = -0.78 to -0.18; p = 0.001) exhibited a more favorable response to the treatments. Furthermore, meta-regression demonstrated that longer periods of supplementation led to significant reductions in methane emissions (p = 0.001), yield (p = 0.032), and intensity (p = 0.012) effect sizes. Overall, the results of the current study suggest that cattle responses to probiotic interventions are highly dependent on the probiotic category. Therefore, extended trials performed with probiotics containing multiple bacterial strains are showing the most promising results. Ideally, further trials focusing on the use of probiotics to reduce ruminal methane in cattle should be conducted to complete the available literature.

Metagenomic sequencing identified microbial species in the rumen and cecum microbiome responsible for niacin treatment and related to intramuscular fat content in finishing cattle

Article

Full-text available

Mar 2024

Introduction Niacin is one of the essential vitamins for mammals. It plays important roles in maintaining rumen microecological homeostasis. Our previous study indicated that dietary niacin significantly elevated intramuscular fat content (IMF) in castrated finishing steers. Whether niacin affects fat deposition by regulating the microbial composition and functional capacities of gastrointestinal microbiome has been unknown yet. Methods In this study, 16 castrated Xiangzhong Black cattle were randomly assigned into either control group fed with a basal concentrate diet (n = 8) or niacin group fed with a basal concentrate diet added 1000 mg/kg niacin (n = 8). Seven rumen samples and five cecum content samples were randomly collected from each of control and niacin groups for metagenomic sequencing analysis. Results A total of 2,981,786 non-redundant microbial genes were obtained from all tested samples. Based on this, the phylogenetic compositions of the rumen and cecum microbiome were characterized. We found that bacteria dominated the rumen and cecum microbiome. Prevotella ruminicola and Ruminococcus flavefaciens were the most abundant bacterial species in the rumen microbiome, while Clostridiales bacterium and Eubacterium rectale were predominant bacterial species in the cecum microbiome. Rumen microbiome had significantly higher abundances of GHs, GTs, and PLs, while cecum microbiome was enriched by CBMs and AAs. We found a significant effect of dietary niacin on rumen microbiome, but not on cecum microbiome. Dietary niacin up-regulated the abundances of bacterial species producing lactic acid and butyrate, fermenting lactic acid, and participating in lipid hydrolysis, and degradation and assimilation of nitrogen-containing compounds, but down-regulated the abundances of several pathogens and bacterial species involved in the metabolism of proteins and peptides, and methane emissions. From the correlation analysis, we suggested that niacin improved nutrient digestion and absorption, but reduced energy loss, and Valine, leucine and isoleucine degradation of rumen microbiome, which resulted in the increased host IMF. Conclusion The results suggested that dietary manipulation, such as the supplementation of niacin, should be regarded as the effective and convenient way to improve IMF of castrated finishing steers by regulating rumen microbiome.

Effects of Dietary Supplementation with Clostridium butyricum on Rumen Fermentation, Rumen Microbiota and Feces in Beef Cattle

Article

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Jan 2024
KAFKAS UNIV VET FAK

From probiotics to postbiotics: Concepts and applications

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Full-text available

Jul 2023

In recent years, the important role of gut microbiota in promoting animal health and regulating immune function in livestock and poultry has been widely reported. The issue of animal health problems causes significant economic losses each year. Probiotics and postbiotics have been widely developed as additives due to their beneficial effects in balancing host gut microbiota, enhancing intestinal epithelial barrier, regulating immunity, and whole‐body metabolism. Probiotics and postbiotics are composed of complex ingredients, with different components and compositions having different effects, requiring classification for discussing their mechanisms of action. Probiotics and postbiotics have considerable prospects in preventing various diseases in the livestock industry and animal feed and medical applications. This review highlights the application value of probiotics and postbiotics as potential probiotic products, emphasizing their concept, mechanism of action, and application, to improve the productivity of livestock and poultry.

Metagenomics-Based Analysis of Candidate Lactate Utilizers from the Rumen of Beef Cattle

Article

Full-text available

Mar 2023

In ruminant livestock production, ruminal acidosis is an unintended consequence of the elevated dietary intake of starch-rich feedstuffs. The transition from a state of subacute acidosis (SARA) to acute acidosis is due in large part to the accumulation of lactate in the rumen, which is a consequence of the inability of lactate utilizers to compensate for the increased production of lactate. In this report, we present the 16S rRNA gene-based identification of two bacterial operational taxonomic units (OTUs), Bt-01708_Bf (89.0% identical to Butyrivibrio fibrisolvens) and Bt-01899_Ap (95.3% identical to Anaerococcus prevotii), that were enriched from rumen fluid cultures in which only lactate was provided as an exogenous substrate. Analyses of in-silico-predicted proteomes from metagenomics-assembled contigs assigned to these candidate ruminal bacterial species (Bt-01708_Bf: 1270 annotated coding sequences, 1365 hypothetical coding sequences; Bt-01899_Ap: 871 annotated coding sequences, 1343 hypothetical coding sequences) revealed genes encoding lactate dehydrogenase, a putative lactate transporter, as well as pathways for the production of short chain fatty acids (formate, acetate and butyrate) and for the synthesis of glycogen. In contrast to these shared functions, each OTU also exhibited distinct features, such as the potential for the utilization of a diversified set of small molecules as substrates (Bt-01708_Bf: malate, quinate, taurine and polyamines) or for the utilization of starch (Bt-01899_Ap: alpha-amylase enzymes). Together, these results will contribute to the continued characterization of ruminal bacterial species that can metabolize lactate into distinct subgroups based on other metabolic capabilities.

B-Group Vitamins as Potential Prebiotic Candidates: Their Effects on the Human Gut Microbiome

Article

Jan 2024
J NUTR

Postbiotics: An overview of concepts, inactivation technologies, health effects, and driver trends

Article

Jun 2023
TRENDS FOOD SCI TECH

Rumen microbial community and milk quality in Holstein lactating cows fed olive oil pomace as part in a sustainable feeding strategy

Article

Apr 2023
ANIMAL

The use of alternative feed ingredients from the Agro-industry could be an efficient tool to improve the sustainability of dairy cow production. Since the richness in polyphenols, olive oil pomace (OOP), produced during olive oil milling, seems a promising by-product to ameliorate milk’s nutritional value. The aim of this study was to test the use of OOP produced by means of a new technology (biphasic with stone deprivation) in dairy cow feeding strategy to evaluate the effect on animal performances, rumen microbiota, biohydrogenation processes and milk quality by a multidisciplinary approach. Forty multiparous Italian-Friesian dairy cows, at middle lactation, were randomly allotted into two homogenous groups and fed respectively a commercial diet (CON) and the experimental diet (OOPD) obtained by adding OOP to CON as partial replacement of maize silage. The two diets were formulated to be isoproteic and isoenergetic. The same diets were tested also in an in vitro trial aimed to evaluate their rumen degradability (% DEG). The dietary supplementation with OOP did not affect DM intake, rumen % DEG and milk production. The milk’s nutritional quality was improved by increasing several important functional fatty acids (FAs; i.e., linoleic acid, conjugated linoleic acid, oleic acid, vaccenic acid). This finding was related to a decrease in rumen liquor biohydrogenation rate of unsaturated FAs. The stochiometric relation between volatile FA production in the rumen and methanogenesis suggested that OOP lowers the methane potential production (CON = 0.050 mol/L vs OOPD = 0.024 mol/L, SEM = 0.005, P = 0.0011). Rumen microbiota and fungi community did not be strongly altered by OOP dietary inclusion because few bacteria were affected at the genus level only. Particularly, Acetobacter, Prevotellaceae_UCG-004, Prevotellaceae_UCG-001, Eubacterium coprostanoligenes, Lachnospira, Acetitomaulatum, Lachnospiraceae_NK3A20 group were more abundant with OOPD condition (P

The effects of lactic acid bacteria and yeast as probiotics on the performance, blood parameters, nutrient digestibility, and carcase quality of rabbits: a meta-analysis

Article

Feb 2023
Ital J Anim Sci

A meta-analysis was conducted to determine the effects of probiotics on the performance, blood parameters, nutrient digestibility and carcase quality of domesticated rabbits. A dataset was constructed based on relevant published papers. An algorithm was constructed from 2004 to 2022, with a search in Scopus, Web of Science, Pub Med, and Medline using the MESH terms ‘probiotics’, ‘rabbit’, ‘performance’, ‘blood parameters’, ‘nutrient digestibility’, and ‘carcasses’. After carefully evaluation, the final dataset consisted 35 in-vivo studies comprising 964 treatment units. The data analysis and coding were performed using software R version 4.2.1 ‘Funny-looking kid’ computing with library mode (cowplot); (tidyverse); and (viridis); and (nlme). The results showed the level of probiotics increased body-weight gain with a linear pattern (p < 0.001). With regard to blood parameters, probiotics decreased triglycerides (p < 0.001) and concomitantly decreased albumin (p < 0.01) in domesticated rabbits. In conclusion, probiotics positively affect parameters for production performance and blood metabolites in domesticated rabbits. • Highlights • Probiotics helps to increased body-weight gain, suppressed triglycerides and albumin • Elevated to carcase yield after exposure to probiotics • Probiotic showed protective effects and enhanced immune systems in domesticated rabbit

Recalculating the global warming impact of italian livestock methane emissions with new metrics

Article

Jan 2023
Ital J Anim Sci

The warming impact of methane (CH4) emissions calculated using the metrics proposed by the Intergovernmental Panel on Climate Change (IPCC), which measure its global warming potential in 100 years (GWP100) expressed as carbon dioxide equivalents (CO2e), accounts for the greatest impact in animal production chains. This work uses the new metrics, proposed to consider the difference between short living climate pollutants (SLCP), such as CH4, and long living climate pollutants (LLCP), such as carbon dioxide (CO2), which measure the warming equivalent (we) effect relative to that of CO2 in a given time frame (GWP*) and expressed as CO2we. The GWP* was applied to CH4 emissions from all Italian livestock supply chains and compared with GWP100 for annual and cumulative assessment from 2010 to 2020 of the impact of this gas on climate change. Using official data published by Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA) from 1990 to 2020, almost all species, except for buffalo (+272.6% of emissions calculated with the new metrics), revealed lower CH4 emissions with the greatest re-dimensioning for non-dairy cattle (-53786 kt of CO2we of calculated with GWP* compared to +66437 kt of CO2e estimated with the GWP100 method). The total cumulative contribution of Italian livestock production to global warming over the past 10 years, including the nitrous oxide (N2O) emissions, has been greatly negative (-48759 kt of CO2we) compared to the data calculated using the GWP100 method (+206091 kt of CO2e). In conclusion, the application of GWP* metric to CH4 emissions of all Italian livestock supply chains allowed to better identify the role of Italian livestock on climate change. Over the 2010–2020 time frame, the Italian animal supply chains reduced the warming impact related to its CH4 emission, with the ruminants (expect buffaloes) being the major contributor to this positive effect. • HIGHLIGHTS • The application of GWP* metric reduced the warming impact of CH4 emissions of Italian dairy cattle, non-dairy cattle, sheep, goats, poultry and rabbits. • The reduction of CH4 emission from the major ruminant species is the major contributor to the positive effect on climate change detected over 2010–2020 time frame. • The application of GWP* metric to CH4 emissions of all Italian livestock supply chains allowed to better identify the role of Italian livestock on climate change.

Assessing the impact of biotics on the ruminal microbiome to enhance sustainability, welfare, and performance in beef cattle: highlighting the omics approach

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