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

Probiotic supplementation in sustainable sheep production: impacts on health, performance, and methane mitigation

Probiotics, defined as live microorganisms conferring health benefits, are increasingly recognized for their potential to enhance animal productivity, mitigate environmental impact, and improve overall animal health. Ruminants, including sheep, are significant contributors to greenhouse gas emissions, a key factor in climate change. Literature from 2003 to 2024 was retrieved from PubMed (Medline), Web of Science, and CAB Direct using the keywords: sheep, sustainability, probiotics, methane emission, and greenhouse gas emissions. The inclusion of probiotics in sheep diets demonstrates potential as a methane mitigation strategy through the stimulation of beneficial bacteria and the suppression of methanogenic microbial activity. Probiotics can improve rumen fermentation parameters by increasing volatile fatty acid production, decreasing protozoal numbers, and improving gas production. Additionally, probiotics can sustain intestinal health, boost nutrient digestibility, and strengthen the immune system. Although promising, the variable effectiveness of probiotics underscores the importance of refining formulations and delivery methods, taking into account strain, dose, and administration. Further studies are crucial to understand the underlying mechanisms and maximize their impact on sheep productivity. This review delves into the potential of probiotics to improve growth, health, and environmental sustainability in the sheep industry, drawing on insights from in vitro and in vivo studies.

Necrophages and necrophiles: a review of their antibacterial defenses and biotechnological potential

With antibiotic resistance on the rise, there is an urgent need for new antibacterial drugs and products to treat or prevent infection. Many such products in current use, for example human and veterinary antibiotics and antimicrobial food preservatives, were discovered and developed from nature. Natural selection acts on all living organisms and the presence of bacterial competitors or pathogens in an environment can favor the evolution of antibacterial adaptations. In this review, we ask if vultures, blow flies and other carrion users might be a good starting point for antibacterial discovery based on the selection pressure they are under from bacterial disease. Dietary details are catalogued for over 600 of these species, bacterial pathogens associated with the diets are described, and an overview of the antibacterial defenses contributing to disease protection is given. Biotechnological applications for these defenses are then discussed, together with challenges facing developers and possible solutions. Examples include use of (a) the antimicrobial peptide (AMP) gene sarcotoxin IA to improve crop resistance to bacterial disease, (b) peptide antibiotics such as serrawettin W2 as antibacterial drug leads, (c) lectins for targeted drug delivery, (d) bioconversion-generated chitin as an antibacterial biomaterial, (e) bacteriocins as antibacterial food preservatives and (f) mutualistic microbiota bacteria as alternatives to antibiotics in animal feed. We show that carrion users encounter a diverse range of bacterial pathogens through their diets and interactions, have evolved many antibacterial defenses, and are a promising source of genes, molecules, and microbes for medical, agricultural, and food industry product development.

Use of Natural Biomolecules in Animal Feed to Enhance Livestock Reproduction

Feed additives are crucial in livestock production, enhancing performance, health, and reproductive efficiency. Recently, there has been a shift toward natural biomolecules as feed additives, specifically targeting improved reproductive outcomes and sperm quality. This transition arises from concerns about antibiotic misuse, antimicrobial resistance, and consumer preferences for eco-friendly products, along with the superior bioavailability, lower toxicity, and reduced environmental impact of natural biomolecules compared to synthetic alternatives. Collaboration among researchers, veterinarians, nutritionists, and regulators is essential to ensure safe and effective livestock management. The review explores advancements in using vital biomolecules in reproductive processes, including plant-derived bioactives such as phytochemicals and antioxidants. It investigates not only the mechanisms but also the intricate interactions of these compounds with animals' hormonal and physiological systems. Additionally, the review critically assesses challenges and prospects related to incorporating natural biomolecules into livestock practices. The potential benefits include enhanced reproductive efficiency and improved sperm quality. However, successful implementation requires understanding factors like precise dosing, potential interactions, and long-term health impacts. Overall, this comprehensive review highlights recent research, technological strides, and the future potential of integrating natural biomolecules into animal diets.

Dynamic Changes in Intestinal Microorganisms and Hematological Indices in Giraffes of Different Ages, and the Effect of Diarrhea on Intestinal Microbiota

This study employed high-throughput sequencing to explore bacterial diversity and hematological variations across different age groups of giraffes, as well as the impact of diarrhea on their intestinal microbiota. Additionally, the correlation between intestinal flora and hematological indices was examined for the first time. Firmicutes, Bacteroides, and Proteobacteria were the predominant bacterial groups in the giraffe's intestinal flora. The α-diversity analysis indicated significant variations in microbial diversity among giraffes of varying ages (p < 0.05). Furthermore, giraffes suffering from diarrhea exhibited significant alterations in the abundance of Proteobacteria and Actinobacteriota at the phylum level (p < 0.05). At the genus level, Rikenellaceae_RC9_gut_group, Monoglobus, and Prevotellaceae_UCG-004 had significant differences compared to healthy counterparts (p < 0.05). Hematological parameters such as lymphocyte count (Lym), red blood cell count (RBC), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), platelet count (PLT), and plateletcrit (PCT) varied significantly across different age groups (p < 0.05). A substantial correlation was observed between the intestinal microbiome composition and hematological parameters (p < 0.05). In conclusion, this study highlights significant differences in both the intestinal microbiome composition and hematological indices among giraffes of different ages. Diarrhea was found to significantly alter the abundance and composition of the intestinal microbial community. These insights provide a valuable theoretical foundation for the microbiological and hematological aspects of giraffe health management and breeding practices.

The ruminant gut microbiome vs enteric methane emission: The essential microbes may help to mitigate the global methane crisis

Ruminants release enteric methane into the atmosphere, significantly increasing greenhouse gas emissions and degrading the environment. A common focus of traditional mitigation efforts is on dietary management and manipulation, which may have limits in sustainability and efficacy, exploring the potential of essential microorganisms as a novel way to reduce intestinal methane emissions in ruminants; a topic that has garnered increased attention in recent years. Fermentation and feed digestion are significantly aided by essential microbes found in the rumen, such as bacteria, fungi, and archaea. The practical implications of the findings reported in various studies conducted on rumen gut concerning methane emissions may pave the way to understanding the mechanisms of CH4 production in the rumen to enhance cattle feed efficiency and mitigate CH4 emissions from livestock. This review discussed using essential bacteria to reduce intestinal methane emissions in ruminants. It investigates how particular microbial strains or consortia can alter rumen fermentation pathways to lower methane output while preserving the health and productivity of animals. We also describe the role of probiotics and prebiotics in managing methane emissions using microbial feed additives. Further, recent studies involving microbial interventions have been discussed. The use of new methods involving functional metagenomics and meta-transcriptomics for exploring the rumen microbiome structure has been highlighted. This review also emphasizes the challenges faced in altering the gut microbiome and future directions in this area.

Performance, ruminal and fecal microbiome of lambs fed diets supplemented with probiotics

The present study aimed to investigate the impact of adding two doses of a commercial probiotic on productive performance, ruminal and fecal microbiome in growing lambs. Forty-two Texel or Ile de France crossbred lambs aged 86.9 ± 8.0 days (body weight: 27.4 ± 3.7 kg) were distributed into three groups: basal diet without probiotic supplementation (CG); basal diet + 1 g/animal/day of probiotic (GP1) and basal diet + 5 g/animal/day of probiotic (GP5). The experimental period was 84 days. The weight was evaluated weekly and dry matter intake (DMI) and leftovers were measured daily. At the end of the experiment, lambs were slaughtered. Feces and rumen fluid were collected for microbiome analysis and rumen fragments for histological evaluation. The use of probiotics did not affect weight gain, but GP1 showed a higher silage and DMI intake than CG (p < 0.001). The CG had a greater thickness of keratinized epithelium and stratum corneum (< 0.001) than GP1 and GP5, and greater total papilla width (p = 0.039) than GP1. There was no difference in the general abundance in the rumen and fecal microbiomes. GP5 had a higher proportion of Azoarcus and Dialister taxa in the rumen fluid (p = 0.012 and p = 0.017, respectively) and higher proportion of Treponema and Fibrobacter taxa in the fecal microbiome (p = 0.015 and p = 0.026, respectively), whereas CG had a higher proportion of Anaeroplasma than the other groups (p = 0.032). These results demonstrated the benefits of probiotics for ruminal epithelium protection and microbial diversity. However, there was no effect on performance parameters.

Animal board invited review: The effect of diet on rumen microbial composition in dairy cows

Ruminants play an important part in the food supply chain, and manipulating rumen microbiota is important to maximising ruminants' production. Rumen microbiota through rumen fermentation produces as major end products volatile fatty acids that provide animal's energy requirements, and microbial CP. Diet is a key factor that can manipulate rumen microbiota, and each variation of the physical and chemical composition creates a specific niche that selects specific microbes. Alteration in the chemical composition of forage, the addition of concentrates in the diet, or the inclusion of plant extract and probiotics, can induce a change in rumen microbiota. High-throughput sequencing technologies are the approaches utilised to investigate the microbial system. Also, the application of omics technologies allows us to understand rumen microbiota composition and these approaches are useful to improve selection programmes. The aim of this review was to summarise the knowledge about rumen microbiota, its role in nutrient metabolism, and how diet can influence its composition.

Survey of the fecal microbiota of indigenous small ruminants living in different areas of Guizhou

Introduction

Gut microbiota are associated with the health and performance of ruminant species, and they are affected by altitude, host genetics, and sex. However, there has been little research on comparing the fecal microbiota of indigenous small ruminants such as sheep and goats in Guizhou province, China. In the present study, we revealed the effect of altitude, genetics, and sex on fecal microbiota profiles and enterotypes in indigenous small ruminants of Guizhou province, China.

Methods

Fecal samples were collected from Hei and Qianbei Ma goats and Weining sheep in the Chinese province of Guizhou. 16S rRNA gene sequencing targeting the V3-V4 region was performed using the Illumina MiSeq platform. Sequences were processed using QIIME2, and the qualified sequences were processed using the plugin DADA2 to generate amplicon sequence variants (ASVs). The statistical analysis was performed using R studio.

Results

The fecal microbial profile was found to vary by herd (influenced by genetics/altitude) and sex. All samples were categorized into two enterotypes. The first enterotype is dominated by UCG-005, and the second enterotype is dominated by the Christensenellaceae_R-7_group, which may be highly driven by the host's genetics (breed). The predicted functional profiles of the fecal microbiota were also assigned to two clusters that corresponded exactly to the enterotypes. Cluster 1 of the functional profiling was characterized by biosynthesis pathways, and cluster 2 was characterized by energy metabolism pathways.

Discussion

Our findings may provide new insights into the fecal microbial community and enterotypes in small ruminants by herds, offering clues for understanding the mechanisms by which the fecal microbiota contribute to divergent host phenotypes in indigenous small ruminants in Guizhou.

Multi-Omics Analysis Reveals the Regulatory Mechanism of Probiotics on the Growth Performance of Fattening Sheep

Probiotics have been proven to improve the growth performance of livestock and poultry. The aim of this experiment was to investigate the effects of probiotic supplementation on the growth performance; rumen and intestinal microbiota; rumen fluid, serum, and urine metabolism; and rumen epithelial cell transcriptomics of fattening meat sheep. Twelve Hu sheep were selected and randomly divided into two groups. They were fed a basal diet (CON) or a basal diet supplemented with 1.5 × 108 CFU/g probiotics (PRB). The results show that the average daily weight gain, and volatile fatty acid and serum antioxidant capacity concentrations of the PRB group were significantly higher than those of the CON group (p < 0.05). Compared to the CON group, the thickness of the rumen muscle layer in the PRB group was significantly decreased (p < 0.01); the thickness of the duodenal muscle layer in the fattening sheep was significantly reduced; and the length of the duodenal villi, the thickness of the cecal and rectal mucosal muscle layers, and the thickness of the cecal, colon, and rectal mucosal layers (p < 0.05) were significantly increased. At the genus level, the addition of probiotics altered the composition of the rumen and intestinal microbiota, significantly upregulating the relative abundance of Subdivision5_genera_incertae_sedis and Acinetobacter in the rumen microbiota, and significantly downregulating the relative abundance of Butyrivibrio, Saccharofermentans, and Fibrobacter. The relative abundance of faecalicoccus was significantly upregulated in the intestinal microbiota, while the relative abundance of Coprococcus, Porphyromonas, and Anaerobacterium were significantly downregulated (p < 0.05). There were significant differences in the rumen, serum, and urine metabolites between the PRB group and the CON group, with 188, 138, and 104 metabolites (p < 0.05), mainly affecting pathways such as vitamin B2, vitamin B3, vitamin B6, and a series of amino acid metabolisms. The differential genes in the transcriptome sequencing were mainly enriched in protein modification regulation (especially histone modification), immune function regulation, and energy metabolism. Therefore, adding probiotics improved the growth performance of fattening sheep by altering the rumen and intestinal microbiota; the rumen, serum, and urine metabolome; and the transcriptome.

Postnatal Growth and Development of the Rumen: Integrating Physiological and Molecular Insights

The rumen plays an essential role in the physiology and production of agriculturally important ruminants such as cattle. Functions of the rumen include fermentation, absorption, metabolism, and protection. Cattle are, however, not born with a functional rumen, and the rumen undergoes considerable changes in size, histology, physiology, and transcriptome from birth to adulthood. In this review, we discuss these changes in detail, the factors that affect these changes, and the potential molecular and cellular mechanisms that mediate these changes. The introduction of solid feed to the rumen is essential for rumen growth and functional development in post-weaning calves. Increasing evidence suggests that solid feed stimulates rumen growth and functional development through butyric acid and other volatile fatty acids (VFAs) produced by microbial fermentation of feed in the rumen and that VFAs stimulate rumen growth and functional development through hormones such as insulin and insulin-like growth factor I (IGF-I) or through direct actions on energy production, chromatin modification, and gene expression. Given the role of the rumen in ruminant physiology and performance, it is important to further study the cellular, molecular, genomic, and epigenomic mechanisms that control rumen growth and development in postnatal ruminants. A better understanding of these mechanisms could lead to the development of novel strategies to enhance the growth and development of the rumen and thereby the productivity and health of cattle and other agriculturally important ruminants.

The Effect of a Direct Fed Microbial on Liveweight and Milk Production in Dairy Cattle

This longitudinal study aimed to quantify the effects of dietary supplementation of a direct-fed microbial (DFM) consisting of three lactobacilli isolates on milk yield, milk fat and protein yields, somatic cell count (SCC), and liveweight in a single dairy herd in Australia. A total of 150 dairy cows were randomly selected based on parity and days in milk and divided into two groups: control (n = 75) and DFM treatment (n = 75). Throughout the study, the two groups of cows were housed separately in a dry lot yard, and each group had their own feeding area. For the DFM treatment group, selected cows in mid-lactation were supplemented with 10 mL/cow/day of the DFM via top dressing of the feed for the remainder of the lactation and through the dry period, extending into subsequent lactation. The control group had no supplementation. The milk yield and liveweight were recorded daily. Milk samples were collected every two months for milk component analysis (fat, protein, and somatic cell count [SCC]). The DFM-treated cows gained more liveweight across the study (19.40 kg, 95% CI 0.44 kg; 38.30 kg, p = 0.05) compared to the control cows. In the second production year, the DFM-treated cows mobilized more liveweight (-6.06 kg, 95% CI -10.49 kg; -1.61 kg, p = 0.01) and produced more milk (0.39 L/d 95% CI 0.10; 0.89, p = 0.05). Over a full lactation, DFM cows yielded at least 258 L (95% CI 252 L; 265 L) more milk than controls. No significant differences were found in fat and protein yield or SCC. This study suggests that consistent and ongoing supplementation with a Lacticaseibacillus- and Lentilactobacillus-based DFM could have a positive effect on milk production, but further research is needed to understand the underlying mechanism.

Characterization of rumen microbiome and immune genes expression of crossbred beef steers with divergent residual feed intake phenotypes

We investigated whole blood and hepatic mRNA expressions of immune genes and rumen microbiome of crossbred beef steers with divergent residual feed intake phenotype to identify relevant biological processes underpinning feed efficiency in beef cattle. Low-RFI beef steers (n = 20; RFI = - 1.83 kg/d) and high-RFI beef steers (n = 20; RFI = + 2.12 kg/d) were identified from a group of 108 growing crossbred beef steers (average BW = 282 ± 30.4 kg) fed a high-forage total mixed ration after a 70-d performance testing period. At the end of the 70-d testing period, liver biopsies and blood samples were collected for total RNA extraction and cDNA synthesis. Rumen fluid samples were also collected for analysis of the rumen microbial community. The mRNA expression of 84 genes related to innate and adaptive immunity was analyzed using pathway-focused PCR-based arrays. Differentially expressed genes were determined using P-value ≤ 0.05 and fold change (FC) ≥ 1.5 (in whole blood) or ≥ 2.0 (in the liver). Gene ontology analysis of the differentially expressed genes revealed that pathways related to pattern recognition receptor activity, positive regulation of phagocytosis, positive regulation of vitamin metabolic process, vascular endothelial growth factor production, positive regulation of epithelial tube formation and T-helper cell differentiation were significantly enriched (FDR < 0.05) in low-RFI steers. In the rumen, the relative abundance of PeH15, Arthrobacter, Moryella, Weissella, and Muribaculaceae was enriched in low-RFI steers, while Methanobrevibacter, Bacteroidales_BS11_gut_group, Bacteroides and Clostridium_sensu_stricto_1 were reduced. In conclusion, our study found that low-RFI beef steers exhibit increased mRNA expression of genes related to immune cell functions in whole blood and liver tissues, specifically those involved in pathogen recognition and phagocytosis regulation. Additionally, these low-RFI steers showed differences in the relative abundance of some microbial taxa which may partially account for their improved feed efficiency compared to high-RFI steers.

Competitive Analysis of Rumen and Hindgut Microbiota Composition and Fermentation Function in Diarrheic and Non-Diarrheic Postpartum Dairy Cows

Postpartum dairy cows can develop nutritional diarrhea when their diet is abruptly changed for milk production. However, it is unclear whether nutritional diarrhea develops as a result of gut acidosis and/or dysbiosis. This study aimed to uncover changes in the gastrointestinal microbiota and its fermentation parameters in response to nutritional diarrhea in postpartum dairy cows. Rumen and fecal samples were collected from twenty-four postpartum cows fed with the same diet but with different fecal scores: the low-fecal-score (LFS: diarrheic) group and high-fecal-score (HFS: non-diarrheic) group. A microbiota difference was only observed for fecal microbiota, with the relative abundance of Defluviitaleaceae_UCG-011 and Lachnospiraceae_UCG-001 tending (p < 0.10) to be higher in HFS cows compared to LFS cows, and Frisingicoccus were only detected in HFS cows. The fecal bacterial community in LFS cows had higher robustness (p < 0.05) compared to that in HFS cows, and also had lower negative cohesion (less competitive behaviors) and higher positive cohesion (more cooperative behaviors) (p < 0.05) compared that in to HFS cows. Lower total volatile fatty acids and higher ammonia nitrogen (p < 0.05) were observed in LFS cows' feces compared to HFS cows. The observed shift in fecal bacterial composition, community networks, and metabolites suggests that hindgut dysbiosis could be related to nutritional diarrhea in postpartum cows.

Effect of coated cysteamine hydrochloride and probiotics supplemented alone or in combination on feed intake, nutrients digestibility, ruminal fermentation, and blood metabolites of Kamphaeng Saen beef heifers

This study aimed to determine the effects of coated cysteamine hydrochloride (CSH) and probiotics (PB) supplemented alone or in combination on feed intake, digestibility, ruminal fermentation, and blood metabolites of heifer beef cattle. Sixteen heifers (body weight = 210 ± 41 kg; age = 9 ± 2 months) were assigned according to a randomized complete block design in a 2 × 2 factorial arrangement. All animals were fed the basal diet, which contained an 82:17 concentrate-to-forage ratio, and the forage source was rice straw. The treatments were as follows: (1) 0% PB + 0 g/d CSH, (2) 0.1% PB + 0 g/d CSH, (3) 0% PB + 20 g/d CSH, and (4) 0.1% PB + 20 g/d CSH. The main effect of CSH supplementation has been found to improve feed intake (P < 0.05). There were no treatment interactions with nutrient digestibility or rumen fermentation parameters. Supplementation of CSH did not affect any of the variables evaluated, while probiotics supplementation increased DM digestibility due to the increases in CP and fiber fraction digestibility. Compared to controls and CSH, at 16 h post-feeding, heifers receiving probiotics tended (P = 0.07) to show 17% greater ruminal NH3-N concentration, but this effect was not evident at 2 h post-feeding. However, the main effects of probiotic supplementation showed a tendency to increase the number of total bacteria and fungal zoospores in the rumen at 2 h post-feeding. The blood triglyceride (BTG) concentration of heifers fed a diet supplemented with 20 g/d CSH and 0.1% probiotics was found to be greater than those fed CSH alone (P < 0.1) at 16 h post-feeding, and then, there were greater BTG concentrations than other treatments (P < 0.05) at 2 h post-feeding. In conclusion, the combination of CSH and PB did not potentiate the effects of probiotics on digestibility and rumen fermentation and had minimal effects on blood parameters.

Microencapsulation of Yarrowia lipolytica: cell viability and application in vitro ruminant diets

Microencapsulation is an alternative to increase the survival capacity of microorganisms, including Yarrowia lipolytica, a widely studied yeast that produces high-value metabolites, such as lipids, aromatic compounds, biomass, lipases, and organic acids. Thus, the present study sought to investigate the effectiveness of different wall materials and the influence of the addition of salts on the microencapsulation of Y. lipolytica, evaluating yield, relationship with cell stability, ability to survive during storage, and in vitro application of ruminant diets. The spray drying process was performed via atomization, testing 11 different compositions using maltodextrin (MD), modified starch (MS) and whey protein concentrate (WPC), Y. lipolytica (Y. lipo) cells, tripolyphosphate (TPP), and sodium erythorbate (SE). The data show a reduction in the water activity value in all treatments. The highest encapsulation yield was found in treatments using MD + TPP + Y. lipo (84.0%) and WPC + TPP + Y. lipo (81.6%). Microencapsulated particles showed a survival rate ranging from 71.61 to 99.83% after 24 h. The treatments WPC + Y. lipo, WPC + SE + Y. lipo, WPC + TPP + Y. lipo, and MD + SE + Y. lipo remained stable for up to 105 days under storage conditions. The treatment WPC + SE + Y. lipo (microencapsulated yeast) was applied in the diet of ruminants due to the greater stability of cell survival. The comparison between the WPC + SE + Y. lipo treatment, wall materials, and the non-microencapsulated yeast showed that the microencapsulated yeast obtained a higher soluble fraction, degradability potential, and release of nutrients.

Innovations for Reducing Methane Emissions in Livestock toward a Sustainable System: Analysis of Feed Additive Patents in Ruminants

Simple Summary

The mitigation of the environmental impact of animal production is a global objective, and innovation can provide new strategies and technologies to support the transition toward a more sustainable livestock system. Using patent data analysis to identify innovation dynamics, we explored the sector of feed additives to reduce methane emissions in ruminants. We found that this innovation sector is recent and rapidly expanding, with the European Union representing the center of innovation. The most promising inventions are related to the use of beneficial microorganisms (probiotics) and plant-based extracts.

Abstract

An important challenge for livestock systems is the mitigation of environmental impacts while ensuring food security, and feed additives are considered as one of the most promising mitigation strategies. This study analyzed the innovation landscape of feed additives to reduce methane emissions in ruminants. The analysis is based on patent data to evaluate the development, scientific importance, and market-level impact of the innovations in this field. The results reveal that the EU is on the innovation frontier, with substantial and quality patent production. The innovation field is dominated by private players, characterized by high specificity in the R&D pipeline. Additives derived from plant or botanical extracts, together with 3-nitrooxypropanol (3-NOP), represent the emerging innovations, indicating a clear orientation toward more sustainable livestock systems. Despite the regulatory and semantic limitations related to the use of patent databases, data reveal a growing innovation activity at global level, which could lead to macroeconomic benefits for the entire livestock sector.

Maternal and infant probiotic administration for morbidity of very low birth weight infants: a three-arm randomized placebo-controlled trial

PURPOSE

To determine whether oral probiotic administration (1.5 × 10⁹ CFU/g Lacticaseibacillus paracasei subsp. paracasei) to breastfeeding mothers or to their very low birth weight (VLBW) infants reduces total serum bilirubin (TSB) level and increases weight gain of the infants.

METHODS

In this double-blind trial, breastfeeding mothers and their VLBW infants at 48-72 h of age were allocated into three groups using stratified block randomization; administrating probiotic to the mothers and placebo to their infants, probiotic to the infants and placebo to their mothers, or placebo to the both. The intervention continued for 28 days.

RESULTS

All 25 mothers and their 26 infants allocated into each group were fully followed up. There were three positive blood culture only in the placebo group. On the 3rd day of intervention, TSB level was not significantly different among the groups but on the 7th day, it was significantly lower in the both probiotic groups compared with the placebo group (mean difference  -2.4 mg/dL [95% confidence interval  -3.6 to  -1.2] in the both comparisons). Mean rank of infant weight gain during the first 7 days of intervention was significantly higher in the both maternal and infant probiotic groups compared with the placebo group (p = 0.007 and p = 0.003, respectively), but there was no statistically significant difference among the groups during the 8th-28th days.

CONCLUSION

Administration of Lacticaseibacillus paracasei to breastfeeding mothers of VLBW infants or to their infants reduces infant TSB level but has no significant effect on weight gain after the first week of the intervention.

TRIAL REGISTRATION

The Iranian Clinical Trials Registry IRCT20100414003706N38. protrospectively registered 24/01/2021.