Effects of mannan-oligosaccharides and Lactobacillus acidophilus supplementation on growth performance, nutrient utilization and faecal characteristics in Murrah buffalo calves

Early life supplementation with mannan-rich fraction to regulate rumen microbiota, gut health, immunity and growth performance in dairy goat kids

Enhancing gastrointestinal health, immunity, and digestion are key factors to support dairy goat kid performance. Several additives have been studied in relation to these actions. This study investigated the impact of mannan-rich fraction (MRF) inclusion in goat milk on the growth performance, gut health, rumen fermentation and microbial profiles of Xinong Saanen dairy goat kids. Eighty kids aged 14 d and 4.72 ± 0.33 kg body weight (BW) were randomly assigned into 2 groups: Control and MRF (1g/d MRF mixed into milk), each group consisted of 40 kids with 10 kids per pen. All kids were given milk individually and fed starter diet by pen, with the trial lasting 10 weeks. BW and blood samples were collected on the 7th day at 2, 6, 10 and 12 weeks of age, and feed intake was determined daily. From the 1st to 7th day at 12 weeks of age, fecal samples were collected on 4 kids from each group to analyze nutrient digestibility. On the 7th day of 12 weeks of age, 4 kids from each group were slaughtered for evaluation of rumen fermentation, rumen microbiota and gut morphology. The results indicated that MRF supplementation led to greater overall BW (P < 0.01), overall starter dry matter intake (DMI) (P < 0.01) and overall average daily gain (ADG) (P = 0.021), while showing lower overall diarrhea rate (P < 0.01). However, no difference in overall feed efficiency (FE) (P = 0.063) and apparent digestibility of nutrients was observed (P > 0.05). Furthermore, MRF supplementation resulted in increased ileal villus height (P = 0.05), and higher RNA expression of Claudin-1 and Occuldin in the duodenum (P < 0.05), ZO-1, JAM-2, and Occuldin in the jejunum (P < 0.05), and Claudin-1, JAM-2, and Occuldin in the ileum (P < 0.05). Additionally, the concentrations of overall IgA, overall IgM and overall IgG were higher in the MRF group (P < 0.01). The concentrations of ruminal acetate and total volatile fatty acid (TVFA) were higher with MRF supplementation (P < 0.05). Meanwhile, supplementation with MRF resulted in higher abundance of Bacteroidetes and Succinivibrio, but lower abundance of Firmicutes and Succiniclasticum in the rumen. In conclusion, growth performance, gut health, immunity, and ruminal microbial structure of dairy goat kids benefited from MRF supplementation.

Non-encapsulated, encapsulated, and lyophilized probiotic Limosilactobacillus reuteri SW23 influenced the growth and gut health in calves

The present study was conducted to assess the impact of non-encapsulated, air-dried microencapsulated, and lyophilized microencapsulated probiotics in indigenous cattle calves (Bos indicus). Twenty-four (5-7 days old) indigenous cattle calves were selected and assigned into four groups, with six calves in each as follows: control (CON), fed milk and basal diet alone, and treatment groups supplemented with non-encapsulated (NEC), air-dried microencapsulated (AEC) and lyophilized microencapsulated (LEC) probiotic L. reuteri SW23 at 108 CFU/head/day in skim milk as a carrier provided for 60 days. The animals were divided into four groups, adopting a complete randomized design, and the effects were considered significant at p ≤ 0.05. Probiotics supplementation increased (p < 0.05) body weight gain (kg), average daily gain, and structural growth measurements in calves of all treatment groups. Dry matter intake (g/d), feed conversion efficiency, and fecal counts of Lactobacilli and Bifidobacteria were also increased in the treatment groups compared to CON. The fecal consistency index was highest in CON (0.70 ± 0.03), followed by NEC (0.68 ± 0.01), AEC (0.66 ± 0.02), and LEC (0.65 ± 0.02). Fecal pH and ammonia levels were reduced (p < 0.05) in the probiotic-fed groups compared to CON, with a concomitant increase in fecal lactate, acetate, and propionate levels. In addition, cell-mediated and humoral immunity were significantly increased in supplemented groups as compared to CON. Thus, it can be concluded that supplementation of the probiotics in microencapsulated/non-encapsulated forms to neonatal calves had a variety of positive effects on their health, including better performance, improved gut health, and a lower fecal consistency index. Moreover, among all supplemented groups, the lyophilized microencapsulated group outperformed air-dried microencapsulated and non-microencapsulated groups in terms of ADG, DMI, and gut health.

Yeast cell wall mannan structural features, biological activities, and production strategies

Mannan and outer structural yeast cell wall polysaccharides have recently garnered attention for their health defense and cosmetic applications. In addition, many studies have confirmed that yeast cell wall mannans exhibit various biological activities, such as antioxidant, immune regulation, reducing hyperlipidemia, and gut health promotion. This paper elucidates yeast cell wall mannan structural features, biological activities, underlying molecular mechanisms, and biosynthesis. Moreover, mannan-overproducing strategies through yeast strain engineering are emphasized and discussed. This review will provide a scientific basis for yeast cell wall mannan research and industrial applications.

Impact of synbiotics on growth performance and gut health in Murrah buffalo calves

Synbiotics have been used as biotherapeutic supplements for prevention of new-born calf gastrointestinal disorders. Present study was conducted to evaluate the impact of fructo-oligosaccharide, mannan-oligosaccharide and inulin along with Lactobacillus plantarum CRD-7 and Lactobacillus acidophilus NCDC15 on the nutrient digestibility, growth performance and faecal microbial population of pre-ruminant buffalo calves. Twenty-four Murrah calves (5 days old) were randomly assigned to four groups of six calves in each using randomized block design. Calves in Group I (control) received only a basic diet of milk, calf starter and berseem with no additives. Calves in Group II (SYN1) were fed 6 g fructo-oligosaccharide (FOS) + Lactobacillus plantarum CRD-7 (100 ml). Calves in Group III (SYN2) were fed 9 g inulin + L. plantarum CRD-7 (50 ml), while calves in Group IV (SYN3) received 4 g MOS + L. acidophilus NCDC15 (200 ml) as fermented milk having 108 CFU/ml/calf/day in addition to the basal diet. The results revealed that digestibility of dry matter, crude protein, ether extract and average daily gain were all higher (P < 0.05) in SYN1 as compared to control group. The antioxidant enzyme activity, humoral and cell mediated immunity performed well in SYN1, SYN2 and SYN3 as compared to control. Diarrhoea and faecal scouring were lower (P < 0.05) in all supplemented groups than control. Faecal Lactobacilli and Bifidobacterium counts were also higher in SYN1 group followed by SYN2 and SYN3. Faecal ammonia, lactate, pH, and volatile fatty acids level were increased in SYN1 supplemented groups. The synbiotic combination of 6 g FOS + L. plantarum CRD-7 had better response on digestibility, average daily gain, antioxidant enzymes, immune response, faecal microbiota and metabolites and also reduce the faecal score and diarrhoea incidence. Therefore, supplementation of 6 g FOS + L. plantarum CRD-7 can be advised for general use in order to promote long-term animal production.

Autochthonous buffalo-gut origin Pediococcus pentosaceus RM119 decreased diarrhea and enhanced gut health, immunity in neonatal Murrah calves

This study assessed the effect of autochthonous probiotic Pediococcus pentosaceus RM119 on gut health, growth, and nutrient utilization in calves. Twelve buffalo calves (<15 d) were divided into two groups, control without probiotics, and probiotic group with P. pentosaceus RM119 @ 108 CFU/calf/d. The probiotic group showed a reduction (p < 0.05) in fecal score, diarrhea episodes and duration of diarrhea. The fecal pH, fecal ammonia was lower, whereas lactate was higher in probiotic group than control. There was a significant increase (p < 0.01) in the concentration of fecal acetate, propionate and butyrate levels in the probiotic supplemented group. The fecal lactobacilli and bifidobacterium were higher (p < 0.01), whereas, fecal coliform and clostridial count were lower (p < 0.01) in P. pentosaceus RM119 supplemented group. There was an improvement in reduced glutathione anti oxidant. Overall, buffalo-gut origin P. pentosaceus RM119 reduced the frequency and severity of diarrhea in neonatal buffalo calves and improved the gut health.

Screening and characterization of Sahiwal cattle calves-origin lactic acid bacteria based on desired probiotic attributes for potential application

Probiotics are living microorganisms that confer health benefits to host when administered in adequate amounts. To develop novel host-specific probiotic for their application as feed additive, the present study was undertaken to isolate and characterize probiotic strains of indigenous cattle-calves origin. A total of 55 colonies were isolated from 12 healthy calves, with 34 of the isolates being Gram-positive, catalase-negative and vancomycin-resistant. Furthermore, eleven isolates showed tolerance to acid (pH 2.0) and thirteen isolates tolerated bile salts (0.3%). Seven common acid and bile tolerance strains were further investigated for other probiotic attributes and displayed higher (p< 0.05) auto-aggregation and cell surface hydrophobicity values. Moreover, all seven isolates had potent antibacterial activity against pathobiont E. coli as well as significant co-aggregation capacity and enzyme activity. In vitro biosafety assessment revealed that all seven isolates were non-hemolytic, negative for mucin degradation and susceptible to most of the antibiotics. Based on the obtained findings, heatmap and principal component analysis identified four highly effective probiotic candidates confirmed by 16S rDNA sequencing as Limosilactobacillus reuteri SW23, Limosilactobacillus reuteri SW26, Limosilactobacillus reuteri SW27 and Enterococcus faecium SW28, respectively. Further studies on biosafety aspect are warranted for the application of these strains in animal as potential probiotics.HIGHLIGHTSL. reuteri SW23, L. reuteri SW26, L. reuteri SW28 and Enterococcus faecium SW28 were successfully isolated and identified from indigenous calves' feces.These microbes were characterized for potential probiotics attributes.Heatmap analysis and principal component analysis (PCA) was used along with probiotic attributes to select highly effective probiotic candidates.

Techno-functional characterization of fecal lactobacilli isolates of Bos indicus calves for probiotic properties

In this study, 105 bacterial colonies were isolated from the feces of newborn healthy Bos indicus calves and 37 isolates were confirmed using morphological, biochemical tests, and genus-specific PCR as lactobacilli. 11 isolates were then short-listed for in vitro probiotic testing based on their ability to dwell under acid and bile stress. Species-level identification using 16S rRNA gene sequencing revealed that they were Ligilactobacillus salivarius. These isolates flourished in 0.4% phenol, depicting resistance in adverse conditions encountered in the gastrointestinal tract. The results of cell surface hydrophobicity were found to be 74.50% for RBL12 and 62.62% for RBL09 in hexadecane and xylene, respectively, and that of auto-aggregation was highest in RBL26 (58.92%). These isolates also produced digestive enzymes like amylase, protease, and β-galactosidase. Further assays reiterated their antimicrobial and coaggregation potential against diarrhea-causing pathogens like Escherichia coli ATCC-25922 and Salmonella arizonae ATCC-13314. Biosafety assessment revealed that none of the tested isolates were hemolytic and mucinolytic in nature. Furthermore, the antioxidant potential of the isolates was also confirmed using 1,1‑diphenyl‑2‑picrylhydrazyl (DPPH) and ferric ion-reducing antioxidant power (FRAP) assay. Along with efficient utilization of inulin, isolates showed promising adhesion ability to the HT-29 cell line. The current findings hence conclude that these Lactobacillus isolates can be exploited as animal probiotics for potential application in young calves to foster gut health and immunity.

Effect of synbiotics on growth performance, gut health, and immunity status in pre-ruminant buffalo calves

Synbiotics are employed as feed additives in animal production as an alternate to antibiotics for sustaining the gut microbiota and providing protection against infections. Dairy calves require a healthy diet and management to ensure a better future for the herd of dairy animals. Therefore, the present study was carried out to investigate the effect of synbiotics formulation on growth performance, nutrient digestibility, fecal bacterial count, metabolites, immunoglobulins, blood parameters, antioxidant enzymes and immune response of pre-ruminant Murrah buffalo calves. Twenty-four apparently healthy calves (5 days old) were allotted into four groups of six calves each. Group I (control) calves were fed a basal diet of milk, calf starter and berseem with no supplements. Group II (SYN1) calves were fed with 3 g fructooligosaccharide (FOS) + Lactobacillus plantarum CRD-7 (150 ml). Group III (SYN2) calves were fed with 6 g FOS + L. plantarum CRD-7 (100 ml), whereas calves in group IV (SYN3) received 9 g FOS + L. plantarum CRD-7 (50 ml). The results showed that SYN2 had the highest (P < 0.05) crude protein digestibility and average daily gain compared to the control. Fecal counts of Lactobacilli and Bifidobacterium were also increased (P < 0.05) in supplemented groups as compared to control. Fecal ammonia, diarrhea incidence and fecal scores were reduced in treated groups while lactate, volatile fatty acids and antioxidant enzymes were improved compared to the control. Synbiotic supplementation also improved both cell-mediated and humoral immune responses in buffalo calves. These findings indicated that synbiotics formulation of 6 g FOS + L. plantarum CRD-7 in dairy calves improved digestibility, antioxidant enzymes, and immune status, as well as modulated the fecal microbiota and decreased diarrhea incidence. Therefore, synbiotics formulation can be recommended for commercial use in order to achieve sustainable animal production.

Using probiotics to improve the utilization of chopped dried date palm leaves as a feed in diets of growing Farafra lambs

The study determined the ability of three probiotics to improve the nutritional value of date palm leaves in diets of growing lambs. Twenty male Farafra lambs (26 ± 0.33 kg) were randomly allocated to one of four treatments (n = 6) and fed: a control or basal diet (C; 70% concentrate + 30% date palm leaves without additives) and supplemented with Bacillofort containing 2 × 1011 CFU of Bacillus subtilis/g (BAC treatment), Lacotpro containing 1 × 1012 CFU of Lactobacillus acidophilus/g (LAC treatment) or ZAD containing 6 × 108 CFU of R. albus/g (ZAD treatment) at 4 g of all additives for 150 days. As a result of this study, LAC improved (P < 0.05) growth performance and feed efficiency compared to control. Additives increased (P = 0.001) concentrations of albumin, triiodothyronine, and thyroxine, hemoglobin concentration and red blood cells and decreased (P = 0.001) globulin and urea-N. Additives increased hot carcass (P = 0.040) while BAC increased Longissimus dorsi, meat and fat without affecting water holding capacity compared to other treatments. In the metabolism experiment, BAC increased the digestibility of crude protein, while BAC and ZAD increased the digestibility of dry matter, organic matter, and neutral detergent fiber. Additives did not affect nitrogen (N) intake and urinary N; however, decreased fecal N and increased N balance compared to the control. BAC and ZAD increased ruminal volatile fatty acids concentration compared to the control. Based on our results, Lacotpro could be used to improve growth performance and feed efficiency, while Bacillofort could be used to improve meat quality of in lambs.

Host-specific probiotics feeding influence growth, gut microbiota, and fecal biomarkers in buffalo calves

The current study is aimed to evaluate the effect of host-specific probiotics on the gut microbiome, performance, and select fecal biomarkers of gut health in preruminant buffalo calves. Eight Murrah buffalo calves (3–5 days old; 32.52 ± 0.43 kg average body weight (BW)) were randomly allocated into two groups as follows; 1) Group I (n = 4) fed basal diet alone (CON); 2) Group II (n = 4) supplemented with a lyophilized probiotic formulation at a dose rate of 1 g/day/head (1 × 10⁹ CFU/g) having Limosilactobacillus reuteri BF-E7 and Ligilactobacillus salivarius BF-17 along with basal diet (PF) for 30 days. Results revealed that final BW (kg), average daily gain (g/day), average dry matter intake (g/day), and structural growth measurements were significantly (P < 0.05) increased in the probiotics supplemented group (PF) compared to the control (CON). Fecal pH, fecal moisture, and fecal score were reduced (P < 0.05) in PF than in CON. Moreover, levels of fecal propionate, lactate, and ammonia altered positively in PF compared with CON. The relative abundance of Firmicutes tended to be higher (P = 0.10) in the probiotics fed group than CON. However, the relative abundance of Proteobacteria was significantly lower (P = 0.03) for calves fed probiotics on day 15. A trend was observed in Bacteroides (P = 0.07) and Lactobacillus (P = 0.08) abundances in the feces of the PF than in CON. Overall, it can be concluded that the administration of probiotic formulations significantly improved the performance and gut health of buffalo calves via modulating the gut microbiota composition.

Effects of dietary supplementation with multispecies probiotics on intestinal epithelial development and growth performance of neonatal calves challenged with Escherichia coli K99

BACKGROUND

Probiotics exhibit antibiotic properties and are capable of treating certain bacterial infections, including diarrhea. Therefore, the aim of this study is to investigate the effects of dietary supplementation with multispecies probiotic (MSP) on diarrhea, average daily gain (ADG) and intestinal development of neonatal calves challenged with Escherichia coli K99.

RESULTS

Thirty-six neonatal Holstein calves were randomly assigned to three treatment groups. After E. coli K99 challenge, calves in the control (C) and MSP treatment groups had significantly higher ADG and feed efficiency, and significantly lower fecal scores than those of calves in the diarrhea (D) group. The mean time of diarrhea resolution was 4.5 and 3.1 days for calves in the D and MSP treatment groups, respectively. Furthermore, the structures of the various segments (duodenum, jejunum and ileum) of the small intestine of the calves, activities of several small intestinal enzymes, and expression of several energy metabolism-related genes in the small intestine segments were significantly affected by MSP treatments.

CONCLUSION

Dietary supplementation of MSP had a positive effect in treating calf diarrhea; it improved ADG and feed efficiency and promoted development of the small intestine. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Impact of Probiotics on Dairy Production Efficiency

There has been growing interest on probiotics to enhance weight gain and disease resistance in young calves and to improve the milk yield in lactating animals by reducing the negative energy balance during the peak lactation period. While it has been well established that probiotics modulate the microbial community composition in the gastrointestinal tract, and a probiotic-mediated homeostasis in the rumen could improve feed conversation competence, volatile fatty acid production and nitrogen flow that enhances the milk composition as well as milk production, detailed changes on the molecular and metabolic level prompted by probiotic feed additives are still not understood. Moreover, as living biotherapeutic agents, probiotics have the potential to directly change the gene expression profile of animals by activating the signalling cascade in the host cells. Various direct and indirect components of probiotic approaches to improve the productivity of dairy animals are discussed in this review.

Feeding Date-Palm Leaves Ensiled with Fibrolytic Enzymes or Multi-Species Probiotics to Farafra Ewes: Intake, Digestibility, Ruminal Fermentation, Blood Chemistry, Milk Production and Milk Fatty Acid Profile

The present experiment evaluated the feeding of date palm leaves (DPL) ensiled with fibrolytic enzymes (ENZ) or multi-species probiotics (MSP) on nutrient utilization and lactational performance of ewes. Fifty multiparous lactating Farafra ewes were used in a completely randomized design for 90 d. The treatments consisted of the control diet with a concentrate feed mixture and date palm leaves (at 60:40, DM basis) ensiled without additive (control) or DPL ensiled with ENZ or MSP replacing control DPL at 50 or 100%. Both ENZ and MSP increased (p < 0.01) DPL and total intakes, digestibility of all nutrients, concentrations of ammonia, total volatile fatty acids, acetate and propionate in the rumen. Increased milk production, concentrations of fat, lactose and energy in milk, and feed efficiency were observed with MSP and ENZ compared to the control treatment. Moreover, ENZ and MSP increased (p < 0.05) the concentrations of total n3, n6 fatty acids, polyunsaturated fatty acids and conjugated linoleic acids and decreased (p < 0.001) the atherogenicity. The differences between ENZ and MSP and between the low and high replacement levels were minor for all measured parameters. Ensiling of DPL with MSP or fibrolytic enzymes is recommended to improve feed efficiency and improve lactational performance of ewes.

Effects of Pathogenic Escherichia coli Infection on the Flora Composition, Function, and Content of Short-Chain Fatty Acids in Calf Feces

Simple Summary

Calf diarrhea caused by bacteria usually begins to occur 2–3 d after birth. The main pathogenic bacteria are Escherichia coli, Campylobacter, Salmonella, and Clostridium perfringens. Pathogenic E. coli is the main bacterium that causes diarrhea in calves. It invades the body of calves and releases enteric toxins that cause diarrhea. The incidence of calf diarrhea caused by pathogenic E. coli O1 can reach 60–70%, even as high as 90–100% in large-scale calf farms, and the mortality rate can reach over 50%. Therefore, the prevention and treatment of calf diarrhea are extremely important. We established a calf diarrhea model by artificially intervening in the colonization of intestinal microbial flora and studied the influence of pathogenic E. coli on the composition, function, and short-chain fatty acid content of calf feces. Our research shows that pathogenic E. coli O1 can significantly reduce the abundance and diversity of calf intestinal microflora, increase harmful bacteria, reduce the colonization of beneficial bacteria, and reduce the short-chain fatty acid content in feces.

Abstract

Calf diarrhea caused by pathogenic Escherichia coli is a major cause of death in calves, with a mortality rate of over 50%. It is crucial to understand the pathogenesis and development of calf diarrhea for its prevention and treatment. We aimed to study the effect of pathogenic E. coli on the flora composition, function, and short-chain fatty acid (SCFA) content of calf feces using a calf diarrhea model. Sixty-four newborn Holstein calves (40–43 kg) were divided into a normal group (NG; n = 32) and a test group (TG; n = 32). At the beginning of the experiment, the TG were orally administered pathogenic E. coli O1 (2.5 × 10¹¹ CFU/mL, 100 mL) to establish a calf diarrhea model, and the NG were orally administered the same amount of physiological saline solution. The calves of the two groups were subjected to the same feeding and management. Fresh feces samples were collected at different time points and subjected to 16S rRNA high-throughput sequencing and gas chromatography–mass spectrometry to determine the fecal microbial composition and SCFA content. Pathogenic E. coli O1 significantly altered microbiotas composition in the feces of calves, increasing the relative abundance of Proteobacteria and decreasing that of Firmicutes. It also led to a significant increase in the relative abundance of Escherichia-Shigella and a decrease in Lactobacillus, as well as significantly decreased SCFA content. Therefore, we postulate that pathogenic E. coli induces calf diarrhea by causing intestinal florae imbalance and reducing the content of SCFA.

Effects of Different Oligosaccharides on Growth Performance and Intestinal Function in Broilers

Objective

This study was conducted to investigate the effects of different oligosaccharides on the growth performance and intestinal function in broilers.

Methods

A total of 360 1-day-old yellow-feather chickens were randomly divided into 5 groups and fed with a basal diet supplemented with 50 mg/kg chlortetracycline (ANT), 3 g/kg isomalto-oligosaccharide (IMO), 3 g/kg raffinose oligosaccharide (RFO), and 30 mg/kg chitooligosaccharide (COS). The experiment lasted for 56 days, with 1–28 days as the starter phase and 29–56 days as the grower phase.

Results

The results showed that dietary supplementation with RFO and COS significantly improved average daily gain (ADG) and average daily feed intake (ADFI) (p &lt; 0.05). Relative to the control group, diets supplemented with oligosaccharides dramatically increased the level of serum IgM (RFO, COS), T-SOD (COS), and GSH-Px (IMO and RFO) and the expression of ZO-1(IMO) and claudin-1 (RFO) (p &lt; 0.05). Adding antibiotics or oligosaccharides to the diet could remarkedly increase the villus height and villus height (VH)/crypt depth (CD) ratio of each group (p &lt; 0.05). Through the ileum α-diversity analysis and comparison of OTU number in each group showed that the microbial richness of the IMO group increased in the starter phase, and that of the RFO and CSO group increased in the grower phase. Additionally, compared with the control group, IMO supplementation increased the level of ileum sIgA (p &lt; 0.05) and the content of valeric acid (p &lt; 0.05) in the cecum.

Conclusions

In summary, the addition of oligosaccharides in diet can improve the immune function and antioxidant capacity and improve intestinal health of broilers.

Role of probiotics in ruminant nutrition as natural modulators of health and productivity of animals in tropical countries: an overview

Given the ever-growing population in the developing countries located in the tropics of Asia, Africa, South America, and the Caribbean, the demand for products of animal origin has increased. Probiotics have proven to be a substantial substitute for antibiotics used in the animal diet and thus gained popularity. Probiotics are live and non-pathogenic microbes commercially utilized as modulators of gut microflora, hence exerting advantageous effects on the health and productivity of animals in tropical countries. Probiotics are mainly derived from a few bacterial (Lactobacillus, Enterococcus, Streptococcus, Propionibacterium, and Prevotella bryantii) and yeast (Saccharomyces and Aspergillus) species. Numerous studies in tropical animals revealed that probiotic supplementation in a ruminant diet improves the growth of beneficial rumen microbes, thus enhancing nutrient intake and digestibility, milk production, and reproductive and feed efficiency, along with immunomodulation. Furthermore, probiotic applications have proven to minimize adverse environmental consequences, including reduced methane emissions from ruminants' anaerobic fermentation of tropical feedstuffs. However, obtained results were inconsistent due to sources of probiotics, probiotic stability during storage and feeding, dose, feeding frequency, and animal factors including age, health, and nutritional status of the host. Furthermore, the mechanism of action of probiotics by which they exhibit beneficial effects is still not clear. Thus, more definitive research is needed to select the most effective strains of probiotics and their cost-benefit analysis. In this review article, we have briefly explained the impact of feeding probiotics on nutrient intake, digestibility, reproduction, growth efficiency, productivity, and health status of tropical ruminant animals.

Immunomodulation Potential of Probiotics: A Novel Strategy for Improving Livestock Health, Immunity, and Productivity

Over the past decade, the use of probiotics as feed supplements in animal production has increased considerably due to the ban on antibiotic growth promoters in livestock. This review provides an overview of the current situation, limitation, and prospects for probiotic formulations applied to livestock. Recently, the use of probiotics in livestock has been suggested to significantly improve their health, immunity, growth performance, nutritional digestibility, and intestinal microbial balance. Furthermore, it was reported that the use of probiotics in animals was helpful in equilibrating their beneficial microbial population and microbial turnover via stimulating the host immune response through specific secretions and competitive exclusion of potentially pathogenic bacteria in the digestive tract. Recently, there has been great interest in the understanding of probiotics targeted diet and its ability to compete with harmful microbes and acquire their niches. Therefore, the present review explores the most commonly used probiotic formulations in livestock feed and their effect on animal health. In summary, this article provides an in-depth knowledge about the formulation of probiotics as a step toward a better alternative to antibiotic healthy growth strategies.

Autochthonous Limosilactobacillus reuteri BFE7 and Ligilactobacillus salivarius BF17 probiotics consortium supplementation improves performance, immunity, and selected gut health indices in Murrah buffalo calves

Probiotics have emerged as biotherapeutic adjuncts to combat neonatal calf gastrointestinal disorders. Therefore, they are considered a suitable alternative to antibiotics for maintaining a healthy and balanced gut microbiota. Hence, the current investigation was carried out to evaluate the effect of autochthonous probiotics on Murrah buffalo calves. Sixteen calves (5-7 days of age) were randomly divided into four groups. Group I served as control (CT), fed a basal diet with no supplementation. Groups II (LR), III (LS), and IV (CS) were supplemented with Limosilactobacillus reuteri BF-E7, Ligilactobacillus salivarius BF-17, and a consortium of both probiotic strains at a rate of 1x10⁸ CFU/g/calf per day along with the basal diet, respectively. Two previously isolated potential probiotic strains, Limosilactobacillus reuteri BF-E7 and Ligilactobacillus salivarius BF-17, were found to be compatible in vitro. Dietary supplementation of probiotics for sixty days significantly increased (P<0.05) dry matter intake (DMI, g/d), average daily gain (ADG, g/d), net body weight gain (kg), feed conversion efficiency (FCE), and structural growth measurements as compared to control. Furthermore, a considerable (P<0.05) increase in the abundance of beneficial intestinal microbiota (lactobacilli and bifidobacteria) was observed along with improvement in fecal biomarkers like lactate and ammonia, immune status, and reduced fecal score. Upon comparative analysis among treatment groups, the results were found to be better in the probiotic consortium fed group compared to the LR and LS treated groups. The present findings conclusively deduced that autochthonous probiotic consortium might serve as potential candidate for fostering performance, immunity, and gut health biomarkers in Murrah buffalo calves.

Supplement Based on Fermented Milk Permeate for Feeding Newborn Calves: Influence on Blood, Growth Performance, and Faecal Parameters, including Microbiota, Volatile Compounds, and Fatty and Organic Acid Profiles

Simple Summary

Gastrointestinal infections and diarrhoea are the main health issues in young calves. The application of microbial products containing probiotics and prebiotics may lead to better management of the gut microbiome and improved calf health. After fermentation with selected lactic acid bacterial strains, milk permeate (a dairy industry by-product) contains lactic acid bacteria and prebiotics, both of which possess viable antimicrobial properties. We hypothesised that fermented milk permeate could be a prospective feed supplement for newborn calves. A 14-day experiment was conducted in which a group of newborn calves were given a supplement of milk permeate fermented with Lactobacillus uvarum LUHS245. A significantly higher count of lactic acid bacteria, a lower total count of enterobacteria, a higher species variety, and greater concentrations of both propionic acid and dry matter were found in the faeces of the calves fed with fermented milk permeate compared with a control group. Most of the fatty acids and volatile compounds in the faeces differed significantly between the two groups. The results suggest that supplementing the calves’ feed with fermented milk permeate has a positive effect on certain health parameters but no influence on blood parameters and growth performance.

Abstract

The aim of this study was to assess the effect of a feed supplement, namely milk permeate (MP) fermented with Lactobacillus uvarum LUHS245, on the newborn calves’ growth performance and blood and faecal parameters, including microbiota and volatile compound and fatty acid profiles. Ten female Holstein calves in the control group (CON group) were fed with a standard milk replacer diet and colostrum only, from day 2 to 14 of life, while 10 calves of the treated group (MP group) were fed with the same diet supplemented with 50 mL of the fermented MP. After 14 days, there were no significant differences between the groups in blood parameters, growth performance, or faecal pH. There was a significantly higher percentage of live lactic acid bacteria (by 17.02%), a lower percentage of enterobacteria (by 10.38%), a higher overall number of probiotic bacteria, a 1.7-fold higher species variety, and a higher content of dry matter in the faeces of the MP group (p < 0.05). The fatty acid and volatile compound profiles differed significantly between the groups. The results suggest that supplementing calves’ feed with fermented milk permeate has a positive effect on certain health parameters but not on blood parameters or growth performance.

Microencapsulated and Lyophilized Lactobacillus acidophilus Improved Gut Health and Immune Status of Preruminant Calves

The present study was conducted to study the effect of microencapsulated, lyophilized, or fermented milk using Lactobacillus acidophilus NCDC15 as a probiotic to improve gut health, growth, nutrient utilization, and immunity status of young crossbred calves. The viable culture of L. acidophilus was used for preparation of different probiotic forms/products. To compare the efficacy of probiotic products, twenty crossbred calves (3-day old) were divided into four groups (n = 5), control (C), fed only milk and basal diet, and treatment groups, supplemented with microencapsulated, fermented, and lyophilized probiotic at 10⁸ colony-forming units, respectively. Probiotic-supplemented groups showed reduction in faecal score, faecal pH, and ammonia concentration as compared to control indicating decreased diarrheal incidence. There was an increase (P < 0.05) in the concentration of faecal lactate and butyrate in the probiotic-supplemented groups. The faecal count (log10 (CFU)/g of fresh faeces) of lactobacilli and bifidobacteria was higher (P < 0.05), whereas faecal coliforms and clostridia count were reduced (P < 0.001) in all the probiotic fed groups as compared to control. The cell-mediated immunity was improved (P < 0.05) in the microencapsulated and fermented probiotic groups. However, there was no effect on the nutrient utilization, average daily gain, and blood biochemical profile. Therefore, it is concluded that the fermented, microencapsulated and lyophilized probiotic products were superior in improving the gut health in terms of its microbiota and metabolites and cell-mediated immunity response in calves, irrespective of form of probiotic. The increased population of Lactobacillus and Bifidobacterium decreased the colonization of the gut by pathogens such as Escherichia coli and Clostridium by exclusion and production of organic acids in the intestine. This decreased the diarrhoeal incidence (1.3 vs 1.8) and days in diarrhoea (3.9 vs 5.8) in calves in probiotic fed groups as compared to control.

Effect of a Multispecies Probiotic Mixture on the Growth and Incidence of Diarrhea, Immune Function, and Fecal Microbiota of Pre-weaning Dairy Calves

The effects of different doses of a multispecies probiotic (MSP) mixture on growth performance, the incidence of diarrhea rate and immune function, and fecal microbial diversity and structure were evaluated in pre-weaning Holstein dairy calves at WK2, WK4, WK6, and WK8. Forty Chinese Holstein female newborn calves were randomly assigned to four treatments with 10 calves in each group, C (control group), T1 (0.5 g MSP/calf/day, T2 (1 g MSP/calf/day), and T3 (2 g MSP/calf/day) groups. The experimental period was 56 days. Feed intake and health scoring were recorded every day until the end of the experiment. Fecal contents and blood samples were sampled at WK2, WK4, WK6, and WK8. Growth performance, incidence of diarrhea, and total serum concentrations (IgA, IgG, and IgM) were analyzed. Bacterial 16S rRNA and fungal ITS genes were high-throughput sequenced for fecal microbiota. The relationships among the populations of the principal fecal microbiota at WK2 and the growth performance or serum immunoglobulin concentrations were analyzed using Pearson's rank correlation coefficients. The MSP supplementation reduced the incidence of diarrhea in the first 4 weeks of life, and serum IgA, IgG, and IgM concentrations increased between WK2 and WK8 in the T3 group. There was an increase in growth performance and reduction in the incidence of diarrhea until WK4 after birth in T3 group, compared with the control, T1, and T2 groups. The results of fecal microbiota analysis showed that Firmicutes and Bacteroides were the predominant phyla, with Blautia, Ruminococcaceae_UCG-005, norank_f__Muribaculaceae, Bacteroides, Subdoligranulum, and Bifidobacterium being the dominant genera in calf feces. Aspergillus, Thermomyces, and Saccharomyces were the predominant fungal phyla. Compared with the control, in T1 and T2 groups, the MSP supplementation reduced the relative abundance of Bacteroidetes and increased the relative abundance of Bifidobacterium, Lactobacillus, Collinsella, and Saccharomyces at WK2 in group T3. Thus, the fecal microbial composition and diversity was significantly affected by the MSP mixture during the first 2 weeks of the calves' life. MSP mixtures reduced the incidence of diarrhea in pre-weaning calves (during the first 4 weeks of life). There was a significant improvement in growth performance, reduction in calf diarrhea, balance in the fecal microbiota, and an overall improvement in serum immunity, compared with the control group. We, therefore, recommend adding 2 g/day of multispecies probiotic mixture supplementation in diets of dairy calves during their first 4 weeks of life before weaning.

Mannan oligosaccharide attenuates cognitive and behavioral disorders in the 5xFAD Alzheimer's disease mouse model via regulating the gut microbiota-brain axis

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by cognitive deficits and psychiatric symptoms. The gut microbiota-brain axis plays a pivotal role during AD development, which could target nutritional intervention. The prebiotic mannan oligosaccharide (MOS) has been reported to reshape the gut microbiome and enhanced the formation of the neuroprotective metabolites short-chain fatty acids (SCFAs). Here, we found that an 8-week treatment of MOS (0.12%, w/v in the drinking water) significantly improved cognitive function and spatial memory, accompanied by attenuated the anxiety- and obsessive-like behaviors in the 5xFAD transgenic AD mice model. MOS substantially reduced the Aβ accumulation in the cortex, hippocampus, and amygdala of the brain. Importantly, MOS treatment significantly balanced the brain redox status and suppressed the neuroinflammatory responses. Moreover, MOS also alleviated the HPA-axis disorders by decreasing the levels of hormones corticosterone (CORT) and corticotropin-releasing hormone (CRH) and upregulated the norepinephrine (NE) expressions. Notably, the gut barrier integrity damage and the LPS leak were prevented by the MOS treatment. MOS re-constructed the gut microbiota composition, including increasing the relative abundance of Lactobacillus and reducing the relative abundance of Helicobacter. MOS enhanced the butyrate formation and related microbes levels. The correlation analysis indicated that the reshaped gut microbiome and enhanced butyrate formation are highly associated with behavioral alteration and brain oxidative status. SCFAs supplementation experiment also attenuated the behavioral disorders and Aβ accumulation in the AD mice brain, accompanied by balanced HPA-axis and redox status. In conclusion, the present study indicated that MOS significantly attenuates the cognitive and mental deficits in the 5xFAD mice, which could be partly explained by the reshaped microbiome and enhanced SCFAs formation in the gut. MOS, as a prebiotics, can be translated into a novel microbiota-targeted approach for managing metabolic and neurodegenerative diseases.

Synbiotic formulation of Cichorium intybus root powder with Lactobacillus acidophilus NCDC15 and Lactobacillus reuteri BFE7 improves growth performance in Murrah buffalo calves via altering selective gut health indices

The objective of this study was to evaluate the effects of synbiotic formulation of Cichorium intybus root powder (C) with Lactobacillus acidophilus NCDC15 (LA) and Lactobacillus reuteri BFE7 (LR) on growth performance in Murrah buffalo calves via monitoring selective gut health indices. Twenty-four Murrah buffalo calves of 5-7 days old and 33 ± 2.0 kg of body weight were distributed randomly into three groups adopting complete randomized design (CRD) as follows: (1) group I served as control (CON) provided with a basal diet alone; (2) group II supplemented with synbiotic formulation of 200 mL L. acidophilus NCDC15 fermented milk with 8 g of Cichorium intybus root powder (LAC) along with basal diet; (3) group III supplemented with synbiotic formulation of 200 mL L. reuteri BFE7 fermented milk with 8 g of Cichorium intybus root powder (LRC) along with basal diet. The final body weight (BW), average dry matter intake (DMI) and structural body measurements were significantly increased (P < 0.05) in LAC and LRC groups by synbiotic as compared to the CON. No effect was registered on apparent nutrient digestibility coefficient of various nutrients in supplemented groups. Faecal score was reduced by the supplementation of synbiotic being lowest in LRC followed by LAC and CON. Calves supplemented synbiotic showed lower (P < 0.05) faecal pH and ammonia with a concomitant increase in faecal lactate levels and faecal short chain fatty acids (SCFA) as compared to control. The faecal Lactobacillus and Bifidobacterium population was increased (P < 0.05) in synbiotic fed groups as compared to control. Additionally, coliform and clostridia count was decreased (P < 0.05) in treatment groups compared to CON. Overall, it may be concluded that synbiotic supplementation was effective in improving the growth performance in Murrah buffalo calves via altering selective gut health indices.

Prebiotic mannooligosaccharides: Synthesis, characterization and bioactive properties

Functional oligosaccharides are non-digestible food ingredients that confer numerous health benefits. Among these, mannooligosaccharides (MOS) are emerging prebiotics that have characteristic potential bio-active properties. Microbial mannanases can be used to break down mannan rich agro-residues to yield MOS. Various applications of MOS as health promoting functional food ingredient may open up newer opportunities in food and feed industry. Enzymatic hydrolysis is the widely preferred method over chemical hydrolysis for MOS production. Presently, commercial MOS is being derived from yeast cell wall mannan and is widely used as prebiotic in feed supplements for poultry and aquaculture. Apart from stimulating the growth of probiotic microflora, MOS impart anticancer and immunomodulatory effects by inducing different gene markers in colon cells. This review summarizes recent developments and future prospects of enzymatic synthesis of MOS from various mannans, their structural characteristics and their potential health benefits.

Systematic review of an intervention: the use of probiotics to improve health and productivity of calves

The aims of this study were to undertake a systematic review and meta-analysis of the types of probiotic formulations that are commercially available and to critically appraise the available evidence for the effectiveness of probiotics in improving the health and productivity of calves. Relevant papers were identified to answer the question: 'In calves aged between birth to one year, is the use of probiotics associated with changes in haematological or biochemical parameters, faecal bacteria counts, average daily live weight gain, dry matter intake, or feed conversion ratio?' The search of the literature yielded 67 studies that fit the primary screening criteria. Included studies were assessed for bias and confounding using a predefined risk assessment tool adapted from the Cochrane Collaboration's tool for assessing risk of bias in randomised trials and GRADE guidelines. Meta-analysis was performed using Review Manager and R. Random sequence generation was low in more than 59 % of studies. Risk of allocation concealment and performance bias were largely unclear in over 68 % of studies. Calves fed probiotics had increased average daily live weight gains (ADG) from birth to weaning (mean difference [MD] = 83.14 g/d 95 % CI = 58.36-107.91, P < 0.001) compared with calves on a control diet. Calf age reduced the level of heterogeneity of the effect of probiotics on ADG for calves between one to three weeks of age (τ² = 73.15; I² = 4%; P = 0.40) but not for calves older than three weeks of age (τ² = 2892.91; I² = 73 %; P < 0.001). Feed conversion ratio (FCR) was lower for calves on probiotics (MD = -0.13 kg of dry matter intake (DMI) to kg of live weight (LW) gain, 95 % CI = -0.17 to -0.09, P < 0.001), and the heterogeneity of effect was large in younger aged calves (τ² = 0.05; I² = 78 %; P = 0.03). The risk of bias regarding the methodology in the included studies was high. The quality of evidence for each outcome was categorised as moderate. There is sufficient data to support the effectiveness of probiotic use in some applications such as for the improvement of performance and productivity parameters of calves. However, the evidence is weak for other potential probiotic uses in calves such as improved health and reduced risk of disease. Therefore, the existing data are inconclusive and do not support the use of probiotics as an alternative to antimicrobials to improve calf health and productivity.

Supplementation of Lactobacillus plantarum or Macleaya cordata Extract Alleviates Oxidative Damage Induced by Weaning in the Lower Gut of Young Goats

Weaning usually leads to stress in livestock, which has a negative impact on their growth and development. Research on oxidative stress and inflammation induced by weaning has not been reported in goats. Here, we focused on oxidative stress profile and inflammation status of the lower gut (jejunum, ileum, and colon) of goats. First, we illustrated the status of antioxidant activity and inflammation in the intestine of young goats on pre-(2 weeks postnatal, 2 wk^pn) or post-(11 wk^pn, weaning at day 45 postnatal)-weaned period of young goats. Malondialdehyde (MDA) was higher (p < 0.0001) in jejunum and ileum of the young goats in 11 wk^pn than that in 2 wk^pn, whereas superoxide dismutase (SOD) activity was lower (p = 0.012) in the lower gut of the young goats with 11 wk^pn than that in 2 wk^pn. Furthermore, we intended to explore the protective influence of a probiotic additive (Lactobacillus plantarum (LAC) P-8, 10 g/d) and a prebiotic additive (Sangrovit^®, Macleaya cordata (MAC) extract 3.75% w/w premix, 0.3 g/d) on intestinal oxidative stress and inflammation status of early-weaned young goats (average weights of 5.63 ± 0.30 kg, weaned on d 45 postnatal). We observed that LAC reduced MDA in jejunum and ileum (p < 0.0001), increased SOD activity in ileum (p < 0.01), and increased glutathione peroxidase (GSH-Px) activity in jejunum (p < 0.05). Similarly, MAC reduced MDA contents (p < 0.0001), increased SOD activities (p < 0.01) in both of ileum and jejunum, and increased GSH-Px activity (p < 0.05) in jejunum. However, there were no differences in feed intake, average daily gain, inflammation parameters (interleukin 2 and interleukin 6), and colon oxidative stress profile (MDA, SOD, or GSH-Px) among treatments. These results provide evidence that weaning induces oxidative damage in the lower gut of young goats, and the oxidative damage in the small intestine can be reduced by adding the addition of LAC or MAC in diets depending on the region of the lower gut.

Effects of Mannan Oligosaccharides on Gas Emission, Protein and Energy Utilization, and Fasting Metabolism in Sheep

Simple Summary

Mannan oligosaccharides (MOS) are a promising feed additive to improve animal health, immune capacity, and antioxidation. Based on the previous studies, we carried out three experiments to investigate the effects of MOS on the gas emission, protein and energy utilization, and fasting metabolism of sheep. The results showed that 2.0% MOS supplementation led to the lowest in vitro CO₂ production and lower CH₄ production and decreased in vivo intake. However, it also decreased urine nitrogen excretion and energy released as CH₄, and then improved the utilization of crude protein and energy of sheep. There were no differences in the parameters of respiration and energy metabolism of sheep under the fasting condition. The findings indicated that MOS slightly affected the gas emission and nutrients and energy utilization of sheep.

Abstract

This study investigated the effects of mannan oligosaccharides (MOS) on in vitro and in vivo gas emission, utilization of crude protein (CP) and energy, and relative parameters of sheep under fasting metabolism conditions. In vitro gas productions were evaluated over 12 h in sheep diets containing different amounts of MOS (from 0% to 6.0%/kg, the increment was 0.5%). A control experiment was used to assess the gas emission, utilization of CP and energy, and fasting metabolism in control sheep and sheep treated with 2.0% MOS over 24 days (d). The results showed that 2.0% MOS supplementation led to the lowest in vitro CO₂ production and less CH₄ production, while also leading to decrease in vivo nutrients intake, CP and energy excretion, digested and retained CP, and energy released as CH₄ (p < 0.05). Furthermore, 2.0% MOS supplementation appeared to decrease in vivo O₂ consumption and CH₄ production per metabolic body weight (BW^0.75), and increase the CP retention rate of sheep (p < 0.074). MOS did not affect other parameters, along with the same parameters of sheep under fasting metabolism conditions (p > 0.05). The findings indicate MOS has only slight effects on the gas emission and nutrients and energy metabolism of sheep.

Microbial Inoculum Composition and Pre-weaned Dairy Calf Age Alter the Developing Rumen Microbial Environment

The objective of this experiment was to determine if dosing pre-weaned calves with enriched ruminal microbiota alters the rumen microbial environment and growth performance. Twenty Holstein bull calves were removed from their dam at birth, fed 3.8 L colostrum within 4 h after birth, and housed individually. Calves were fed pasteurized milk 3×/d from 0 to 7 weeks of age and offered a texturized calf starter ad libitum at 6 days of age. A randomized complete block design with repeated measures and a 2 × 2 factorial arrangement of treatments was used to evaluate responses. Treatments were administered by stomach intubation once per week from 3 to 6 weeks of age and included: 50 mL autoclaved rumen fluid (RF), 50 mL bacterial-enriched RF (BE), 50 mL protozoal-enriched RF (PE); or 50 mL of each BE and PE inoculum. A rumen content composite was collected from 4 rumen fistulated, lactating cows and used to create the inocula. BE inocula were microscopically confirmed to be free of ciliate protozoa before inoculation, while PE contained 2.9 ± 2.2 × 10⁵ protozoa/mL. RF was collected from the calves once per week before 50 mL of the inoculum was administered. Animal performance (e.g., weight gain and dry matter intake) was not altered by inocula type. All calves were microscopically free of rumen ciliates before inoculum administration and calves that did not receive PE remained ciliate-free. Ciliate protozoa were observed in RF from 6, 8, and 6 PE treated calves (n = 10) at weeks 4, 5, and 6, respectively. Ruminal NH₃ was lower in PE treated calves (3.3 vs. 6.8 ± 1.0 mM), while ruminal butyrate molar percent was greater in BE treated calves (10.8 vs. 8.3 ± 0.8). Rumen bacterial diversity measures did not differ by treatment at 3-6 weeks. Individual calf bacterial communities from treated calves became temporarily similar to the inocula at 4 weeks of age, but these communities diverged from the inocula at 5 weeks. This study provides new information about two types of rumen-derived inocula and insight into the challenges of directing the rumen microbial environment in the pre-weaned calf.

Effects and immune responses of probiotic treatment in ruminants

Gut microbial colonization and establishment are vital to ruminant health and production. This review article focuses on current knowledge and methods used to understand and manipulate the gut microbial community in ruminant animals, with a special focus on probiotics treatment. This review highlights the most promising of studies in this area, including gut microbial colonization and establishment, effect of gastrointestinal tract microbial community on host mucosal innate immune function, impact of feeding strategies on gut microbial community, current probiotic treatments in ruminants, methods to manipulate the gut microbiota and associated antimicrobial compounds, and models and cell lines used in understanding the host immune response to probiotic treatments. As a lot of work in this area was done in humans and mice, this review article also includes up-to-date knowledge from relevant studies in human and mouse models. This review is a useful resource for scientists working in the areas of ruminant nutrition and health, and to researchers investigating the microbial ecology and its relation to animal health.

Dissect the mode of action of probiotics in affecting host-microbial interactions and immunity in food producing animals

Prophylactic antimicrobials have been widely used in food animal production with the aim to prevent infectious diseases, enhance feed efficiency, and promote growth. However, the extensive use of antimicrobials in food animal production systems has led to the emergence of antimicrobial resistant pathogens, which are potential threats to human and animal health. Probiotics have been proposed to be a promising alternative of prophylactic antimicrobials, with potential beneficial effects on the host animal by improving the balance of intestinal microbiota and host immunity. Although an increasing body of evidence shows that probiotics could directly or indirectly affect gut microbiota and host immune functions, the lack of the understanding of how probiotics influence host-microbial interaction and immunity is one of the reasons for controversial findings from many animal trials, especially in food production animals. Therefore, in this review we focused on the most recent (last ten years) studies on how gut microbiota and host immune function changes in response to probiotics in food production animals (swine, poultry, and ruminant). In addition, the relationship between microbial changes and host immune function was illustrated, and how such relationship differs among animal species was further compared. Moreover, the future directions concerning the mechanisms of how probiotics modulate host-microbial interactions and host immunity were highlighted, which may assist in the optimal supplementation strategy to maximize the efficacy of probiotics to improve animal gut health and productivity.