Effects of Lactobacillus cultures on growth performance, abdominal fat deposition, serum lipids and weight of organs of broiler chickens

Effects of Lactobacillus acidophilus on production performance and immunity of broiler chickens and their mechanism

Introduction

Lactobacillus species have attracted more and more attention as a potential antibiotic substitute for human health and animal production due to their remarkable antibacterial effects. However, the underlying mechanism is unclear. This experiment's goal was to investigate the impacts of lactic acid bacteria (LAB) on the growth performance, carcass characteristics, immune function of broiler chickens and their mechanism.

Methods

One hundred and eighty 1-day-old AA broilers were used and randomly allocated into 3 treatment groups with 6 replicates of 10 chickens per replicate. The 3 treatment groups were control group (CK), L. acidophilus added group (LAB-E, 1.0 × 108 CFU/kg) for the first 7 days; L. acidophilus added group (LAB-A, 1.0 × 108 CFU/kg) for the whole experimental period. Broilers had free access to water and feed.

Results

The results showed that addition of L. acidophilus for the whole experimental period significantly decreased ADFI, FCR and the abdominal fat percentage of broilers (p < 0.05), tended to increase the levels of IgG in broiler serum (p = 0.093). The LAB-A group had higher HDL-C content and IL-2, IL-4 content, and lower level of LPS in broiler serum compared to the controls (p < 0.05).

Discussion

In conclusion, L. acidophilus improved feed efficiency and immune function of broilers by controlling nutrient metabolism and inflammation responses of broilers. L. acidophilus can be used as a potential substitute for antibiotics in broiler production.

Lactiplantibacillus plantarum ameliorated the negative effects of a low-protein diet on growth performance, antioxidant capacity, immune status, and gut microbiota of laying chicks

This experiment was conducted to investigate the effects of adding Lactiplantibacillus plantarum to a low-protein diet on the growth performance, ability immune status, and intestinal microbiota of 0-21-day-old layer chickens. A total of 180 one-day-old healthy Hy-line brown laying chicks were randomly divided into three groups with three replicates each of 20 chicks. The control group was fed a basal diet containing 19% protein, the low-protein (LP) group was fed a diet containing 17% protein, and the probiotic (LPL) group was fed with the 17% protein diet supplemented with L. plantarum (1.0 × 109 CFU/kg). The growth performance, antioxidant capacity, immune status, and gut microbiota of laying chickens were detected. We found that L. plantarum supplementation increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and levels of immunoglobulin (Ig) A, IgG, and interleukin-10 (IL-10) in serum of 17% protein +1.0 × 109 CFU/kg L. plantarum (LPL) compared to the 19% protein group (control). Furthermore, L. plantarum supplementation increased the liver index, GSH-Px and T-AOC activity in serum, and changed the microflora structure, diversity, and polyketose unit bioanabolic metabolism of 17% protein +1.0 × 109 CFU/kg L. plantarum (LPL) compared to the 17% protein group (LP). In conclusion, L. plantarum supplementation could compensate for the adverse effects of low-protein diets in chicks, and the combination of a low-protein diet and L. plantarum is a feasible way to reduce protein in the diet.

Probiotic Supplementation Alleviates Corticosterone-Induced Fatty Liver Disease by Regulating Hepatic Lipogenesis and Increasing Gut Microbiota Diversity in Broilers

Emerging evidence indicates a close relationship between gut microbiota and fatty liver disease. It has been suggested that gut microbiota modulation with probiotics ameliorates fatty liver disease in rodents and humans, yet it remains unclear whether the same results will also be obtained in poultry. The aim of this study was to investigate whether a mixture of probiotics supplemented after hatching can prevent CORT-induced fatty liver disease in broilers, and to determine how such effects, if any, are associated with hepatic de novo lipogenesis and gut microbiota composition. Ninety-six one-day-old green-legged chickens were divided into a control group (CON) and probiotic group (PB). At 28 days of age, fatty liver was induced in 16 broilers that were randomly selected from the CON or PB group. At the end of the experiment, broilers from four groups, (i) the control group (CON), (ii) corticosterone group (CORT), (iii) probiotic group (PB), and (iv) PB plus CORT group (CORT&PB), were slaughtered for sampling and analysis. The results showed that probiotic administration significantly prevented CORT-induced body weight loss (p < 0.05) but did not alleviate the weight loss of immune organs caused by CORT. Compared to CON, the broilers in the CORT group exhibited a significant increase in triglyceride (TG) levels in plasma and liver (p < 0.01), as well as severe hepatocytic steatosis and hepatocellular ballooning, which was accompanied by the upregulation of hepatic lipogenesis gene expression. However, probiotic supplementation markedly decreased the intrahepatic lipid accumulation and steatosis histological score, which was associated with the downregulation of sterol regulatory element-binding protein-1 (SREBP1) and acetyl-CoA carboxylase (ACC) mRNA (p < 0.05) and the expression of its protein (p = 0.06). The cecal microbiota composition was determined by 16S rRNA high-throughput sequencing. The results showed that CORT treatment induced distinct gut microbiota alterations with a decrease in microbial diversity and an increase in Proteobacteria abundance (p < 0.05). In contrast, probiotic supplementation increased the beta diversity, the community richness, and the diversity index (p > 0.05), as well as the abundance of Intestinimonas (p < 0.05). Our results indicate that CORT treatment induced severe fatty liver disease and altered the gut microbiota composition in broilers. However, post-hatching probiotic supplementation had a beneficial effect on alleviating fatty liver disease by regulating lipogenic gene expression and increasing gut microbiota diversity and the abundance of beneficial bacteria. We demonstrate for the first time that the supplementation of probiotics to chicks had a beneficial effect on preventing fatty liver disease through regulating lipogenic gene expression and improving the gut microbial balance. Thus, our results indicate that probiotics are a potential nutritional agent for preventing fatty liver disease in chickens.

Effect of Lactobacillus paracasei LK01 on Growth Performance, Antioxidant Capacity, Immunity, Intestinal Health, and Serum Biochemical Indices in Broilers

This study aimed to investigate the effects of adding L. paracasei LK01 to the diet on the growth performance, antioxidant capacity, immunity, intestinal health, and serum biochemical indicators of broilers. This study selected 1080 one-day-old broiler chickens with similar body weight, and randomly divided them into six groups, with six replicates in each group and 30 chicks in each replicate. The chicks were fed (1) the basal diet (CON), (2) the basal diet with 106 CFU/kg L. paracasei LK01(T1), (3) the basal diet with 107 CFU/kg L. paracasei LK01(T2), (4) the basal diet with 108 CFU/kg L. paracasei LK01(T3), (5) the basal diet with 109 CFU/kg L. paracasei LK01(T4), and (6) the basal diet with 1010 CFU/kg L. paracasei LK01(T5). The experiment lasted for 42 days. In this study, compared with the CON group, the diet supplemented with L. paracasei significantly increased body weight from 1 to 21 days (p < 0.05). In addition, the 106 CFU/kg L. paracasei LK01 group significantly reduced the activity of glutamic oxaloacetic transaminase and triglyceride levels; the 107 CFU/kg,108 CFU/kg, and 109 CFU/kg L. paracasei LK01 groups also reduced serum uric acid and total cholesterol levels (p < 0.05). The experimental groups all had lower serum levels of malondialdehyde and interleukin-1β (p < 0.01). Except for the 106 CFU/kg group, all experimental groups had significantly lower tumor necrosis factor-α, and the 106 and 107 CFU/kg groups had higher immunoglobulin M levels (p < 0.05). In addition, the 106 CFU/kg group significantly reduced the depth of the ileocecal crypts and increased the villus-to-crypt ratio (V/C) of the jejunum and ileum. In addition, dietary supplementation with L. paracasei LK01 did not change the α diversity of the microbial community in the cecum, but significantly increased the proportion of Bacteroides (phylum) (p < 0.05). The 106 CFU/kg group also significantly increased the abundance of beneficial bacteria such as Ruminococcaceae (genus), Lachnospiraceae (genus), and Faecalibacterium (genus) (p < 0.05). In summary, this study revealed that adding 106 CFU/kg of L. paracasei LKO1 to broiler diets can improve their production performance, serum biochemical indicators, antioxidant, and immune capabilities, as well as cecal flora.

Plasma activated water effects on behavior, performance, carcass quality, biochemical changes, and histopathological alterations in quail

BACKGROUND

Plasma-activated water (PAW) is an innovative promising technology which could be applied to improve poultry health. The current study investigated the effects of drinking water supply with PAW on quail behaviour, performance, biochemical parameters, carcass quality, intestinal microbial populations, and internal organs histopathology. A total of 54 twenty-one-day-old Japanese quail chicks were randomly allotted to three treatments provided with PAW at doses 0, 1 ml (PAW-1), and 2 ml (PAW-2) per one litter drinking water. Each treatment contained 6 replicates (3 birds/ cage; one male and two females).

RESULTS

The results clarified that there were no significant (P > 0.05) changes in behaviour, and performance. For the biochemical indicators, the PAW-1 group showed significantly higher serum H2O2, total protein and globulin levels compared with the other groups (P = 0.015, < 0.001, and 0.019; respectively). PAW groups had significantly lower serum creatinine and urea levels than the control (P = 0.003). For the carcass quality, the internal organs relative weight between different treatments was not changed. In contrast, there was a significant increase in the meat colour, taste, and overall acceptance scores in PAW groups compared with the control one (P = 0.013, 0.001, and < 0.001; respectively). For the intestinal microbial population, lactobacilli count was significantly higher in PAW-2 compared with the control group (P = 0.014), while there were no changes in the total bacterial count between different treatment groups. Moreover, mild histological changes were recorded in the intestine, liver, and spleen of PAW groups especially PAW-2 compared with the control one.

CONCLUSIONS

PAW offered benefits, such as reducing creatine and urea levels, improving meat characteristics, and increasing lactobacilli count, all of which are crucial for sustainable quail farming. Therefore, further research is needed.

Nutraceuticals vs. antibiotic growth promoters: differential impacts on performance, meat quality, blood lipids, cecal microbiota, and organ histomorphology of broiler chicken

The main goal of this study was to evaluate the effect of nutraceuticals vs. in-feed antibiotics on performance, blood lipids, antioxidant capacity, cecal microbiota, and organ histomorphology of broiler chickens. A total of 320 one-day-old male broiler chickens were distributed into 5 treatment groups with 8 replicates each. The control group was fed on a basal diet without any additives (NC); the antibiotic group was fed on a basal diet supplemented with 100 mg kg-1 avilamycin (PC); the algal group was fed on a basal diet supplemented with a mixture of Spirulina platensis and Chlorella vulgaris (1.5 g + 1.5 g/kg feed) (SP+CV); the essential oil group was fed with a basal diet containing 300 mg/kg feed rosemary oil (REO); and the probiotics group (a mixture of 1 × 1011 CFU/g Bacillus licheniformis, 1 × 1011 CFU/g Enterococcus facieum, 1 × 1010 CFU/g Lactobacillus acidophilus, and 2 × 108 CFU /g Saccharomyces cerevisiae) was fed with a basal diet supplemented with 0.05% probiotics (PRO). The experiment lasted for 35 d. A beneficial effect of SP+CV and PRO (P < 0.01) was noticed on final body weight, body weight gain, feed conversion ratio, and breast yield. The dietary supplementation with SP+CV, REO, and PRO increased (P < 0.001) broilers' cecal lactic acid bacteria count compared to the control. Lower cecal Clostridium perfringens and Coliform counts (P < 0.001) were noticed in chickens fed the PC and supplemental diets. Malondialdehyde (MDA) concentration was decreased, while glutathione peroxidase (GPx), superoxide dismutase, and catalase enzymes were increased in the breast and thigh meat (P < 0.001) of broiler chickens fed SP+CV, REO, and PRO diets. Dietary SP+CV, REO, and PRO supplementation decreased (P < 0.001) serum total lipids, cholesterol, triglycerides, low-density lipoprotein, and MDA, but increased serum high-density lipoprotein and GPx compared to PC and NC. No pathological lesions were noticed in the liver, kidney, or breast muscle among broilers. The SP+CV, REO, and PRO groups had greater (P < 0.001) intestinal villi height and crypt depth while lower goblet cell densities (P < 0.01) than the control. The present findings suggest that PRO and SP+CV, followed by REO could be suitable alternatives to in-feed antibiotics for enhancing the performance, health, and meat quality of broiler chickens.

Effect of High Dietary Iron on Fat Deposition and Gut Microbiota in Chickens

To meet the demand of consumers for chicken products, poultry breeders have made improvements to chickens. However, this has led to a new problem in the modern poultry industry, namely excessive fat deposition. This study aims to understand the effects of dietary iron supplementation on fat deposition and gut microbiota in chickens. In this study, we investigated the effects of iron on the growth performance, fat deposition, and gut microbiota of silky fowl black-bone chickens. A total of 75 7-week-old silky fowl black-bone chickens were randomly divided into three groups (five replicates per group, five chickens per replicate) and fed them for 28 days using a growing diet (control group), a growing diet + 10% tallow (high-fat diet group, HFD group), and a growing diet + 10% tallow + 500 mg/kg iron (HFDFe500 group), respectively. We detected the effects of iron on the growth performance, fat deposition, and gut microbiota of silky fowl black-bone chickens using the growth performance index test, oil red O staining, and HE staining, and found that the high-fat diet significantly increased liver and serum fat deposition and liver injury, while the addition of iron to the diet could reduce the fat deposition caused by the high-fat diet and alleviate liver injury. In addition, 16S rDNA sequencing was used to compare the relative abundance of gut microbiota in the cecal contents in different feeding groups. The results showed that the high-fat diet could induce gut microbiota imbalance in chickens, while the high-iron diet reversed the gut microbiota imbalance. PICRUSt functional prediction analysis showed that dietary iron supplementation affected amino acid metabolism, energy metabolism, cofactors, and vitamin metabolism pathways. In addition, correlation analysis showed that TG was significantly associated with Firmicutes and Actinobacteriota (p < 0.05). Overall, these results revealed high dietary iron (500 mg/kg) could reduce fat deposition and affect the gut microbiota of silky fowl black-bone chickens, suggesting that iron may regulate fat deposition by influencing the gut microbiota of chickens and provides a potential avenue that prevents excessive fat deposition in chickens by adding iron to the diet.

Harnessing probiotics capability to combat Salmonella Heidelberg and improve intestinal health in broilers

The poultry industry faces significant challenges in controlling Salmonella contamination while reducing antibiotic use, particularly with the emergence of Salmonella Heidelberg (SH) strains posing risks to food safety and public health. Probiotics, notably lactic acid bacteria (LAB) and Saccharomyces boulardii (SB) offer promising alternatives for mitigating Salmonella colonization in broilers. Understanding the efficacy of probiotics in combating SH and their impact on gut health and metabolism is crucial for improving poultry production practices and ensuring food safety standards. This study aimed to assess the inhibitory effects of LAB and SB against SH both in vitro and in vivo broilers, while also investigating their impact on fecal metabolites and caecal microbiome composition. In vitro analysis demonstrated strong inhibition of SH by certain probiotic strains, such as Lactiplantibacillus plantarum (LP) and Lacticaseibacillus acidophilus (LA), while others like SB and Lactobacillus delbrueckii (LD) did not exhibit significant inhibition. In vivo testing revealed that broilers receiving probiotics had significantly lower SH concentrations in cecal content compared to the positive control (PC) at all ages, indicating a protective effect of probiotics against SH colonization. Metagenomic analysis of cecal-content microbiota identified predominant bacterial families and genera, highlighting changes in microbiota composition with age and probiotic supplementation. Additionally, fecal metabolomics profiling showed alterations in metabolite concentrations, suggesting reduced oxidative stress, intestinal inflammation, and improved gut health in probiotic-supplemented birds. These findings underscore the potential of probiotics to mitigate SH colonization and improve broiler health while reducing reliance on antibiotics.

Comparative analysis between multi-strain probiotics and antibiotic as starter feed supplement of poultry on growth performance, serum metabolites and meat quality

The unobstructed use of antibiotics in poultry production has emerged as a major driving force of antibiotic resistance and public health hazard, particularly in developing countries. This study aimed to determine the functional roles of lyophilized native probiotic based starter feed on performance, selective serum metabolites and meat quality of poultry. A total of 90 day-old birds (30 broilers, 30 layers and 30 ducks) were used as experimental birds which were divided into three treatment groups for each kind of bird. Isolated native probiotic strains from chicken intestine were used to prepare lyophilized probiotic samples. Growth performances were measured manually, serum biochemicals analysis were carried out using diagnostic kits, and meat quality was determined through Kjeldahl method and Soxhlet method. When compared to groups receiving antibiotics, the introduction of lyophilized probiotics in starter feed significantly (P<0.05) increased body weight gain, feed intake, and feed conversion ratio. The birds' serum calcium and protein levels likewise exhibited a similar pattern. Comparing the groups receiving antibiotics, the protein content of the meat revealed significant (P<0.05) variations. Significant (P<0.05) reduced level of serum total cholesterol, triglycerides and fat content in meat was observed when compared to antibiotic-fed group. It is possible to conclude that lyophilized probiotics have a significant positive impact on growth performance, serum metabolites and meat quality. The findings of the study could open up new avenues for the application and adoption of native probiotic-based poultry feeds as an alternative to antibiotic-based poultry feeds among stakeholders.

Diet composition influences probiotic and postbiotic effects on broiler growth and physiology

Dietary ingredient and nutrient composition may affect the efficacy of additives in broilers. Specific feed ingredients can represent dietary challenging conditions for broilers, resulting in impaired performances and health, which might be alleviated by dietary probiotics and postbiotics. We assessed the effects of a Lactobacilli probiotic (Pro) and postbiotic (Post) when added to a standard (SD) and challenge (CD) diet. A completely randomized block study with 2 diets (SD, CD) and 3 additive conditions (Control, Pro and Post) involving 1,368 one-day-old Ross male broilers, equally distributed among 36 pens, from d1 to d42 was conducted. Both diets were formulated to contain identical levels of nutrients, with CD formulated to be richer than SD in nonstarch polysaccharides using rye and barley as ingredients. Readout parameters included growth performance parameters, footpad lesions score, blood minerals and biochemical parameters, and tibia health, strength, and composition. Compared to SD, CD decreased BW (1,936 vs. 2,033 g; p = 0.001), increased FCR (p < 0.01) and impaired tibia health and strength (p < 0.05) at d35, thereby confirming the challenging effect of CD. Pro and Post increased BW in CD (+4.7 and +3.2%, respectively, at d35; P < 0.05) but not in the SD group, without affecting FCR. Independently of the diet, Pro increased plasma calcium, phosphorus and uric acid at d21 (+6.2, +7.4, and +15.5%, respectively) and d35 (+6.6, +6.2 and +21.0%, respectively) (P < 0.05) while Post increased plasma magnesium only at d21 (+11.3%; P = 0.037). Blood bile acids were affected by additives in an age- and diet-dependent manner, with some opposite effects between dietary conditions. Diet composition modulated Pro and Post effects on broiler growth performance. Additionally, Pro and Post affected animal metabolism and leg health diet-dependently for some but not all investigated parameters. Our findings show that the effects of pro- and postbiotics on the growth performance and physiology of broilers can be dependent on diet composition and thus possibly other factors affecting diet characteristics.

The "crosstalk" between microbiota and metabolomic profile in high-fat-diet-induced obese mice supplemented with Bletilla striata polysaccharides and composite polysaccharides

The potential prebiotic feature of Bletilla striata polysaccharides (BSP) has been widely accepted, while the beneficial effect of BSP on high-fat-diet-induced obesity is unclear. Moreover, the "crosstalk" between microbiota and metabolomic profile in high-fat-diet-induced obese mice supplemented with BSP still need to be further explored. The present study attempted to illustrate the effect of BSP and/or composite polysaccharides on high-fat-diet-induced obese mice by combining multi-matrix (feces, urine, liver) metabolomics and gut microbiome. The results showed that BSP and/or composite polysaccharides were able to reduce the abnormal weight gain induced by high-fat diet. A total of 175 molecules were characterized by proton nuclear magnetic resonance (1H NMR) in feces, urine and liver, suggesting that multi-matrix metabolomics could provide a comprehensive view of metabolic regulatory mechanism of BSP in high-fat-diet-induced obese mice. Several pathways were altered in response to BSP supplementation, mainly pertaining to amino acid, purine, pyrimidine, ascorbate and aldarate metabolisms. In addition, BSP ameliorated high-fat-diet-induced imbalanced gut microbiome, by lowering the ratio of Firmicutes/Bacteroidetes. Significant correlations were illustrated between particular microbiota's features and specific metabolites. Overall, the anti-obesity effect of BSP could be attributed to the amelioration of the disorders of gut microbiota and to the regulation of the "gut-liver axis" metabolism.

Research Note: In ovo and in-feed probiotic supplementation improves layer embryo and pullet growth

Probiotics are widely used as feed supplements in the poultry industry to promote growth and performance in chickens. Specifically, this supplementation starts around the time of lay and continues through the production cycle in laying hens. However, the embryonic period is critical to the growth and development of metabolically active organs thereby influencing subsequent health and productivity in adult birds. Therefore, the present study investigated the potential use of probiotics to promote embryonic growth in layers. Further, a pilot grow-out study was conducted to evaluate the effect of in ovo and in-feed probiotic application on pullet growth. For the study, fertile White Leghorn eggs were sprayed with phosphate buffered saline (control, CON) or probiotic cocktail (in ovo only, IO; Lactobacillus paracasei DUP 13076 and L. rhamnosus NRRL B 442) prior to and during incubation. The embryos were sacrificed on d 7, 10, 14, and 18 of incubation for embryo morphometry. On d 18, remaining eggs were set in the hatcher to assess hatchability and hatchling morphometry. For the pullet trial, hatchlings were raised on feed with or without probiotics until wk 5. Pullets were sacrificed weekly, and morphometric parameters were recorded. Results of our study demonstrate that in ovo probiotic application significantly improved relative embryo weight, crown-rump length, hatchability, and hatchling weight when compared to the control (P < 0.05). Further, this enhanced embryonic development was associated with a concomitant increase in posthatch growth. Specifically, pullets raised from probiotic-sprayed eggs had significantly improved crown-rump length, tibial length, tibial bone weight, and body weight when compared to the control (P < 0.05). Moreover, among the different treatment schemes employed in this study [CON (no probiotics), in-feed only (IF), IO only, and in ovo and in-feed probiotic supplementation (IOIF)], sustained probiotic supplementation (IOIF) was found to be the most effective in promoting growth. Therefore, in ovo and in-feed probiotic supplementation could be employed to promote embryo and pullet growth to support subsequent performance in layers.

Use of Postbiotic as Growth Promoter in Poultry Industry: A Review of Current Knowledge and Future Prospects

Health-promoting preparations of inanimate microorganisms or their components are postbiotics. Since probiotics are sensitive to heat and oxygen, postbiotics are stable during industrial processing and storage. Postbiotics boost poultry growth, feed efficiency, intestinal pathogen reduction, and health, making them acceptable drivers of sustainable poultry production. It contains many important biological properties, such as immunomodulatory, antioxidant, and anti-inflammatory responses. Postbiotics revealed promising antioxidant effects due to higher concentrations of uronic acid and due to some enzyme's production of antioxidants, e.g., superoxide dismutase, glutathione peroxidase, and nicotinamide adenine dinucleotide oxidases and peroxidases. Postbiotics improve intestinal villi, increase lactic acid production, and reduce Enterobacteriaceae and fecal pH, all of which lead to a better immune reaction and health of the gut, as well as better growth performance. P13K/AKT as a potential target pathway for postbiotics-improved intestinal barrier functions. Similarly, postbiotics reduce yolk and plasma cholesterol levels in layers and improve egg quality. It was revealed that favorable outcomes were obtained with various inclusion levels at 1 kg and 0.5 kg. According to several studies, postbiotic compounds significantly increased poultry performance. This review article presents the most recent research investigating the beneficial results of postbiotics in poultry.

Dynamic distribution of gut microbiota in posthatching chicks and its relationship with average daily gain

The colonization and development of gut microbiota are essential for the health and growth of chicks after hatching. However, the colonization and prevalence of gut microbiota have not been well characterized, and knowledge of which microbes and their relationship with average daily gain in chicks is still limited. This study characterized the dynamic succession of microbiota in the intestinal tract of chicks and investigated its relationship with daily weight gain. A total of 121 fecal samples across 7 time points from d 0 to 10 posthatching were collected from 19 chicks randomly selected from 1,950 chicks. Using 16S rRNA gene sequencing examined microbial composition of fecal samples. The observed species index of alpha diversity increased with age, gradually achieving stability at 3 d of age. The microbiota of chicks after hatching was primarily Clostridium_sensu_stricto_1 (34.49%), and its relative abundance diminishes with age. In contrast, Lactobacillus had a low relative abundance in the first 2 d after hatching and gradually increased with age. Predicted functional capacities found that the microbiota of early-stage posthatching (d 0 and 1 after hatching) was involved in metabolism, including amino acid metabolism, metabolism of cofactors and vitamins, and nitrogen metabolism. However, at the later stage posthatching (from d 3-10 after hatching), the intestinal microbial function was involved in carbohydrate metabolism, amino acid metabolism, cell growth and death, and methane metabolism. It was identified that 47 operational taxonomic units were associated with average daily gain of chicks, 12 of which were annotated with Lactobacillus and significantly positive associated with average daily gain. In addition, Clostridium_sensu_stricto_1 was significantly negatively associated with average daily gain. Taken together, we characterized the dynamic successions of intestinal microbiota in hatching chicks. The intestinal microbiota of chicks has an impact on the host average daily gain. Our findings should be instrumental in improving local chick production.

Probiotics as an alternative to antibiotics in modulating the intestinal microbiota and performance of broiler chickens

AIMS

Gut bacteria play an important role in poultry nutrition and the immune defense system. Changes in the intestinal microbiome affect the physiological state, metabolism, and innate immunity of poultry. The present study aimed to characterize age-related changes in the gastrointestinal tract microflora in broiler chickens, depending on supplementation of the diet with the in-feed antibiotic Stafac® 110 and a Bacillus subtilis strain-based probiotic.

METHODS AND RESULTS

In this regard, a comprehensive analysis of the taxonomic structure of the microbial community in the gastrointestinal tract (GIT) of broiler chickens was carried out using a molecular genetic technique of the terminal-restriction fragment length polymorphism analysis and taking into account age dynamics and feeding treatment. A beneficial effect on the microbiological composition and body weight of broilers was observed when using the antibiotic and probiotic in compound feeds. Different bacterial communities were revealed in the duodenum and cecum, and their positive impact on broiler growth was established. The results obtained shed light on the formation of GIT microflora of broiler chickens during the growing period and its changes in response to the use of the antibiotic and the probiotic.

CONCLUSIONS

We suggest that the implementation of the tested in-feed antibiotic and probiotic can be beneficial in regulating the intestinal microflora microbiological processes in the GIT and improving the feeding efficiency and productivity of broiler chickens.

Antimicrobial peptides act on the rumen microbiome and metabolome affecting the performance of castrated bulls

BACKGROUND

Many countries have already banned the use of antibiotics in animal husbandry, making it extremely difficult to maintain animal health in livestock breeding. In the livestock industry, there is an urgent need to develop alternatives to antibiotics which will not lead to drug resistance on prolonged use. In this study, eighteen castrated bulls were randomly divided into two groups. The control group (CK) was fed the basal diet, while the antimicrobial peptide group (AP) was fed the basal diet supplemented with 8 g of antimicrobial peptides in the basal diet for the experimental period of 270 d. They were then slaughtered to measure production performance, and the ruminal contents were isolated for metagenomic and metabolome sequencing analysis.

RESULT

The results showed that antimicrobial peptides could improve the daily weight, carcass weight, and net meat weight of the experimental animals. Additionally, the rumen papillae diameter and the micropapillary density in the AP were significantly greater than those in the CK. Furthermore, the determination of digestive enzymes and fermentation parameters showed that the contents of protease, xylanase, and β-glucoside in the AP were greater than those in the CK. However, lipase content in the CK was greater than that in the AP. Moreover, the content of acetate, propionate, butyrate, and valerate was found to be greater in AP than those in CK. The metagenomic analysis annotated 1993 differential microorganisms at the species level. The KEGG enrichment of these microorganisms revealed that the enrichment of drug resistance-related pathways was dramatically decreased in the AP, whereas the enrichment of immune-related pathways was significantly increased. There was also a significant reduction in the types of viruses in the AP. 187 probiotics with significant differences were found, 135 of which were higher in AP than in CK. It was also found that the antimicrobial mechanism of the antimicrobial peptides was quite specific. Seven low-abundance microorganisms (Acinetobacter_sp._Ac_1271, Aequorivita soesokkakensis, Bacillus lacisalsi, Haloferax larsenii, Lysinibacillus_sp._3DF0063, Parabacteroides_sp._2_1_7, Streptomyces_sp._So13.3) were found to regulate growth performance of the bull negatively. Metabolome analysis identified 45 differentially differential metabolites that significantly different between the CK and the AP groups. Seven upregulated metabolites (4-pyridoxic acid, Ala-Phe, 3-ureidopropionate, hippuric acid, terephthalic acid, L-alanine, uridine 5-monophosphate) improve the growth performance of the experimental animals. To detect the interactions between the rumen microbiome and metabolism, we associated the rumen microbiome with the metabolome and found that negative regulation between the above 7 microorganisms and 7 metabolites.

CONCLUSIONS

This study shows that antimicrobial peptides can improve the growth performance of animals while resisting viruses and harmful bacteria and are expected to become healthy alternatives to antibiotics. We demonstrated a new antimicrobial peptides pharmacological model. We demonstrated low-abundance microorganisms may play a role by regulating the content of metabolites.

Effect of yeast culture supplementation on blood characteristics, body development, intestinal morphology, and enzyme activities in geese

The objective of this experiment is to evaluate the effects of yeast culture (YC) supplementation on blood characteristics, body size, carcass characteristics, organ weights, intestinal morphology, and enzyme activities. Five groups of geese were randomly assigned to five dietary treatments: the basal diet (control) and basal diets plus 0.5%, 1.0%, 2.0%, or 4.0% YC. Compared with the controls, YC supplementation at 0.5% and 1.0% increased the serum total protein (TP), albumin (ALB), and globulin (GLO) and decreased the uric acid and creatine kinase (CK) contents (p < 0.05). YC supplementation at 2.0% and 4.0% increased the CK, growth hormone, catalase and glutathione reductase contents, and relative proventriculus weights, and decreased the TP, ALB, and GLO contents, relative liver, gizzard, jejunum, ileum, and thymus weights (p < 0.05). YC supplementation at 2.0% improved fossil bone length, breast muscle percentage, jejunal villus height, ileal and jejunal villus height/crypt depth ratios, pepsin, lipase, amylase and pancreatic trypsin activities, and decreased abdominal fat percentage (p < 0.05). Furthermore, YC inclusion increased the body slope length (linear, p = 0.002; quadratic, p = 0.02), breast width (quadratic, p = 0.02), ileal (linear, p = 0.04; quadratic, p = 0.01) and duodenal villus height (cubic, p = 0.04), and decreased the relative gizzard (quadratic, p = 0.04) and thymus (linear, p = 0.002; quadratic, p = 0.02; cubic, p = 0.02) weights, liver (linear, p = 0.002; quadratic, p = 0.02), and serum (linear, p = 0.006; quadratic, p = 0.03) malondialdehyde contents, and jejunal crypt depth (quadratic, p = 0.03). The findings indicated that the YC supplementation had a positive effect on the growth and development of geese, with 2% YC being the most effective.

Alleviation of Catching and Crating Stress by Dietary Supplementation of Bacillus subtilis in Pekin Ducks

Catching and crating may elicit stress and fear reactions in poultry because the procedures involve human contact and exposure to a novel environment. This study determined the effects of dietary probiotic supplementation on physiological stress, underlying fear, and growth performance of Pekin ducks subjected to catching and 4 h of crating. The study used a 2 × 2 factorial arrangement; the main factors were diet (basal or basal + probiotic) and crating durations (0 or 4 h). From 1 to 21 days of age (doa), birds were fed a basal or basal + probiotic (CLOSTAT® (Bacillus subtilis) (Kemin Industries, Inc., Des Moines, IA, USA), 1 g/kg) diet. At 21 doa, an equal number of ducklings from each dietary group were caught and crated for 4 h or left undisturbed in the home pens. Birds were examined for serum corticosterone (CORT), heat shock protein (HSP) 70, creatine kinase (CK), triglyceride (TG), glucose (GLU), cholesterol (CHOL), and lactate (LAC) concentrations, heterophil to lymphocyte ratios (HLR), tonic immobility (TI) duration, open-field (OF) test, body weight (BW), and feed conversion ratios (FCR). Diet had no significant (p > 0.05) effect on CORT among the non-crated ducks. However, after catching and crating, birds fed the control diet had significantly (p < 0.05) higher CORT than their probiotic-supplemented counterparts. Catching and crating significantly (p < 0.05) elevated HSP70, HLR, GLU, and CHOL but reduced TG in ducks. Birds fed the probiotic-supplemented diet showed significantly (p < 0.05) lower HSP70, HLR, TG, and CK than those fed the control diet. Probiotic-supplemented ducks showed reduced fear-related behaviours, including TI durations, ambulation latency, and body shaking. Diet had a negligible effect on body weights and FCR of ducks at 21 doa. In brief, catching and crating for 4 h augmented Pekin ducks’ physiological stress and fear reactions, and supplementing birds with probiotics was beneficial in ameliorating these detrimental effects.

Effects of oral exposure to leachate from boiled-water treated plastic products on gut microbiome and metabolomics

By simulating plastic exposure patterns in modern society, the impact of daily exposure to plastic products on mammals was explored. In this study, Institute for Cancer Research (ICR) mice were used to establish drinking water exposure models of three popular kinds of plastic products, including non-woven tea bags, food-grade plastic bags and disposable paper cups. Feces and urine of mice were collected for gut microbiome and metabolomics analysis. Our results showed that the diversity and composition of gut microbiota changed at genus level compared to control group. Lactobacillus, Parabacteroides, Escherichia-shigella and Staphylococcus decreased while Lachnospiraceae increased treated with non-woven tea bags. Escherichia-shigella and Alistipes increased while Parabacteroides decreased treated with food grade plastic bags. Muribaculaceae decreased in the gut microbiota of mice treated with disposable paper cups. Metabolomics has seen changes in the number of metabolites and enrichment of metabolic pathways related to inflammatory responses and immune function. Inflammatory responses were found in histological and biochemical examination. In summary, this study demonstrated that long-term oral exposure to leachate form boiled-water treated plastic products might have effects on gut microbiome and metabolome, which further provided new insights about potential adverse effects for human beings.

Arsenic trioxide modulates the composition and metabolic function of the gut microbiota in a mouse model of rheumatoid arthritis

The mechanism of rheumatoid arthritis (RA) has been widely investigated, and studies on the use of arsenic trioxide (ATO) in the treatment of RA have been reported in recent years. However, the exact mechanism of action of ATO in RA remains unclear. This study explores alterations in the gut microbiota and metabolism during ATO treatment in a mouse model of RA and provides an integrative analysis of the biomechanism. The purpose of this study was to verify whether ATO can alleviate RA by altering the gut microbiota. In this study, the mice were randomly divided into four different groups: the normal control (NC) group, the collagen-induced arthritis (CIA) group, the ATO 1.0 mg/kg/day group, and the ATO 2.0 mg/kg/day group. Fecal samples were collected. Through 16S rDNA gene sequencing and metabolomic analysis, the effect of ATO on the composition and metabolites of gut microbiota in CIA mice was investigated. The results showed that compared with NC mice, CIA mice showed differences at both the phylum level (Firmicutes and Bacteroidetes) and the genus level (Muribaculaceae_unclassified and Alistipes). Meanwhile, many metabolites were significantly changed between the two groups, including benzoic acid and (s)-2-acetolactate. However, these alterations were partially reversed in ATO-treated CIA mice. These results indicated that ATO treatment modulated gut microbiota disorder and improved fecal metabolite abnormalities. In conclusion, this study provided important evidence for alterations of the gut microbiota and metabolites and the role of these alterations in a potential novel mechanism of ATO treatment in RA.

L-serine improves lipid profile, performance, carcass weight and intestinal parameters in feed restricted broiler chickens during the hot-dry season

The study evaluated effects of L-serine on lipid profile, performance, carcass weight and small intestinal parameters in heat-stressed broiler chickens subjected to feed restriction. Broiler chickens were divided into four groups, comprising 30 each. Group 1, feed restriction (FR); Group 2, feed restriction + L-serine (200 mg/kg) (FR + L-serine); Group 3, ad libitum (AL); Group 4, ad libitum + L-serine (200 mg/kg) (AL + L-serine). L-serine was administered orally from days 1 to 14, and feed restriction was performed on days 7-14. Serum harvested from blood samples on days 21, 28 and 35 was evaluated for lipid profile. Feed and water intake, live weight gain, organ and carcass weight were measured. At 35 days old, broiler chickens (n = 7) per group were sacrificed to evaluate small intestinal morphology. Temperature-humidity index in the pen (30.88 ± 0.81) was above thermoneutral zone, indicating that chickens were subjected to heat stress. Concentrations of low-density lipoprotein, total cholesterol and total triglycerides were lower (p < 0.05), while higher concentration of high-density lipoprotein was recorded in L-serine groups than in the controls. Feed intake and live weight gain on day 35 in L-serine groups were higher (p < 0.05) than in controls. In L-serine groups, liver, spleen, pancreas and heart weight were higher, but abdominal fat was lower than in FR and AL groups. Villus height:crypt height ratio and area of villus surface were highest in L-serine groups than any other group. In conclusion, L-serine decreased low-density lipoprotein, increased feed intake, live weight, organ and carcass weight, villus height:crypt height ratio and villus surface area.

The effect of a postbiotic produced by stabilized non-viable Lactobacilli on the health, growth performance, immunity, and gut status of colisepticaemic broiler chickens

This work was designed to evaluate the efficacy of a postbiotic compound produced by stabilized non-viable Lactobacilli on the health, growth performance, immunity, and gut status against Escherichia coli (E. coli) challenge of broiler chickens. A total of 400, day-old broiler chicks were allocated into 4 equal groups (1–4) consisting of 100; each assigned into 2 equal replicates (50 each). Chickens in the 1st group were received the dry form of the compound at doses of 1 kg and 0.5 kg/ton feed for starter and grower, and the finisher diets, respectively. Chickens in the 2nd group were given the aqueous form of the compound in a dose of 4 mL/L of the drinking water during the first 3 days of life and at a day before and after each vaccination. Feed and water treatment regimens were administered to chickens in the 3rd group. Group 4 was kept without treatment. Each bird in the 1st, 2nd, 3rd, and 4th group was challenged with E. coli (O78) at 1-week-old. All groups were kept under observation till 5-week-old. Statistical analysis included one-way ANOVA and other methods as described with significant differences at P ≤ 0.05. The results indicated that feed and water treatments with the postbiotic compound induced more significant (P ≤ 0.05) amelioration of a disease picture, enhancement of growth performance, boosting of immune response, improvement of bursa of Fabricius/body weight ratio, and reduction of intestinal coliform count in challenged chickens when compared with challenged non-treated chickens. In conclusion, the postbiotic compound either in a dry and/or an aqueous form is recommended for improving the health, performance, and immunity of colisepticaemic broiler chickens.

Potential Substitutes of Antibiotics for Swine and Poultry Production

Early of the last century, it was detected that antibiotics added to the animal feeds at low doses and for a long time can improve technical performances such as average daily gain and gain-to-feed ratio. Since then, the antibiotics have been used worldwide as feed additives for many decades. At the end of the twentieth century, the consequences of the uses of antibiotics in animal feeds as growth promoters were informed. Since then, many research studies have been done to find other solutions to replace partly or fully to antibiotic as growth promoters (AGPs). Many achievements in finding alternatives to AGPs in which probiotics and direct-fed microorganism, prebiotics, organic acids and their salts, feed enzymes, bacteriophages, herbs, spices, and other plant extractives (phytogenics), mineral and essential oils are included.

Oyster (Crassostrea gigas) polysaccharide ameliorates obesity in association with modulation of lipid metabolism and gut microbiota in high-fat diet fed mice

Oyster is nutritious shellfish, wildly consumed throughout the world. Its polysaccharide (OPS) has various bioactivity. In the present study, the anti-obesity effect of OPS was evaluated in obese mice induced by a high-fat diet (HFD). The results showed that OPS significantly alleviated weight gain, dyslipidemia, and metabolic endotoxemia of obese mice, and accelerated the production of short-chain fatty acids. OPS also regulated lipid metabolism of adipose and liver by activating the expression of p-AMPKα to further down-regulate the expression of SREBP-1c, PPARγ, and p-ACC-1. 16S rRNA results indicated that OPS corrected HFD-induced gut microbiota dysbiosis by enriching beneficial bacteria (Bifidobacterium, Lactobacillus, Dobosiella, and Faecalibaculum) and decreasing harmful bacteria (Erysipelatoclostridium, Helicobacter, and Mucispirillum). In summary, these results revealed that OPS could serve as a potential prebiotic to improve obesity.

Protective effects of probiotics against tannin-induced immunosuppression in broiler chickens

Tannins (TAs) are an anti-nutritional substance commonly used as a natural feed additive for livestock. However, our previous study described the dose-dependent adverse effects of TA on immune responses and growth in chickens. In this study, we evaluated the protective effects of a probiotic preparation (BT) consisting of three different bacteria (Bacillus mesenteric, Clostridium butyricum, and Streptococcus faecalis) against TA-induced immunosuppression in chickens. Forty chicks were divided into 4 groups as follows: the CON group (basal diet), BT group supplemented with 3 g BT/kg diet, tannic acid (TA) group supplemented with 30 g TA/kg diet, and BT+TA group supplemented with 3 g BT/kg diet + 30 g TA/kg diet. The feeding trial lasted for 35 days. Lymphocyte subset, macrophage phagocytosis, cytokine mRNA expression, and primary and secondary IgY immune responses were evaluated. BT supplementation significantly improved TA-induced reductions in final body weight, body weight gain, feed intake, and relative weights of lymphoid organs compared with the TA group. Furthermore, in the spleen and cecal tonsil (CT), the relative populations of CD4+, CD8+, and CD4+CD8+ cells in the BT+TA group were significantly ameliorated compared with the TA group. Additionally, comparison with the TA group showed that the chickens in the BT+TA group had an improved relative population of B cells in the CT and that macrophage phagocytosis in the spleen was significantly increased. Chickens in the BT+TA group showed significant increases in IFN-γ and IL-4 mRNA expression in the spleen compared with the TA group. The primary and secondary IgY responses were significantly improved. These results revealed that supplementation with BT protects against TA-induced immunosuppression in chickens.

Effects of Yeast Culture Supplementation on Growth Performance, Nutrient Digestibility, Blood Metabolites, and Immune Response in Geese

The present study was conducted to investigate the effects of dietary yeast culture (YC) supplementation on growth performance, nutrient digestibility, blood metabolites, and immune functions in geese. One-day-old Sichuan white geese (n = 300) were randomly divided into five groups containing 0 (control), 0.5%, 1.0%, 2.0%, and 4.0% of YC in the diet for 70 days. In general, the dietary supplementation of YC significantly increased the average daily gain and feed conversion ratio (p < 0.05) in which the 1.0% or 2.0% levels were better and significantly reduced the average daily feed intake at the 2.0% level (p < 0.05). YC supplementation increased digestibility of P (quadratic, p = 0.01) and gross energy (quadratic, p = 0.04) from days 23 to 27 and crude protein from days 23 to 27 and days 64 to 68 (quadratic, p ≤ 0.05), with the 2.0% level being the most effective. Serum metabolites were significantly affected by dietary YC (p < 0.05). Supplemental YC increased IL-2 on day 28 (linear, p = 0.01; quadratic, p = 0.04) and lysozyme on day 70 (quadratic, p = 0.04) and decreased complement C4 on day 70 (linear, p = 0.05). Interferon-γ, interleukin-2, and tumor necrosis factor-α genes were mostly up-regulated after YC supplementation, and interferon-γ and interleukin-2 gene expression levels were significantly increased at the 2.0% level (p < 0.05). Taken together, dietary YC supplementation improved growth performance and affected nutrient digestibility, serum metabolites, and immune function in geese, which was optimized at the 2% YC level in the present study.

Effect of Two Soybean Varieties Treated with Different Heat Intensities on Ileal and Caecal Microbiota in Broiler Chickens

Simple Summary

Soybeans are an essential part of today’s poultry nutrition diets because of their high protein content and quality. To ensure optimum digestibility in monogastric animals, soybeans need to be thermally processed. As required heat intensities depend on individual soybean properties, the emergence of highly heterogenic soybean batches is a challenge for adequate processing conditions. Molecular changes occurring during heat treatment can alter the microbial communities colonizing the animals’ guts. Gut microbiota is of great importance for both its host animal’s performance and health. To investigate the effect of heat treatment and soybean variety on the chickens’ microbiota, two soybean varieties were selected, treated at two different heat intensities and subjected to a feeding trial. DNA was then extracted and sequenced to identify different bacterial populations in the digesta of certain gut sections. Results showed that both the soybean variety and the applied heat treatment affected the abundance of certain bacterial species in the gut of chickens, but no effect on the taxonomy level of family or genus appeared. This underlines the sensitivity and reactivity of the highly complex microbial community to apparently small dietary differences.

Abstract

Soybean products are of high importance for the protein supply of poultry. Heat treatment of soybeans is essential to ensure optimal digestibility because of intrinsic antinutritive factors typical for this feed category. However, excessive treatment promotes the Maillard reaction and reduces protein digestibility. Furthermore, Europe’s efforts are to decrease dependence on imports of soybean products and enlarge local production. This process will include an increase in the variability of soybean batches, posing great challenges to adequate processing conditions. Intrinsic soybean properties plus heat treatment intensity might be able to modulate the gut microbiota, which is of crucial importance for an animal’s health and performance. To assess the influence of heat treatment and soybean variety on gut microbiota, 2 soybean cakes from 2 varieties were processed at 110 °C or 120 °C and subsequently fed to 336 one-day-old broiler chickens. After 36 days, the animals were slaughtered, and the digesta of the ileum and caecum was collected. Next, 16S rRNA amplicon sequencing of the extracted DNA revealed a high discrepancy between gut sections, but there were no differences between male and female birds. Significant differences attributed to the different soybean varieties and heat intensity were detected for certain bacterial taxa. However, no effect on specific families or genera appeared. In conclusion, the results indicated the potential of processing conditions and soybean variety as microbiota-modulating factors.

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.

The Efficiency of Probiotics Administrated via Different Routes and Doses in Enhancing Production Performance, Meat Quality, Gut Morphology, and Microbial Profile of Broiler Chickens

Simple Summary

Antimicrobial growth promoters (AGPs) have been used in the animal production industry around the world for decades, with the consequence of a high potential of antibiotic-resistant bacteria transfer to humans. Efficiently raising broiler chickens in an antibiotic-free production system is a challenge, and identifying an effective nutritional alternative to support growth performance, gut health, and functionality without administrating AGPs is of essence. Several antimicrobial alternative options that are commercially available include herbal essential oils, exogenous enzymes, organic acids, plant secondary metabolites, probiotics, and prebiotics. Probiotics in animal feed is projected to attain a massive global growth, reaching USD 6.24 billion by 2026. This study tested the efficiency of probiotics when supplemented via different administration routes (feed or water) and doses, or in combination with prebiotics, on growth performance, meat quality, gut morphology, and microbial profile of broiler chickens. The outcomes revealed that probiotics enhance production performance, and compared to AGPs, do not reduce the beta-diversity of the gut microbial community. Water-soluble probiotics seemed to be more effective in improving growth performance.

Abstract

To study the efficiency of Bacillus spp. probiotics administered via different routes and doses, a 6-week grow-out trial was conducted using a total of 378 day-old mixed-sex ROSS308 broiler chickens in a completely randomized block design. Six experimental diets included probiotics added at two different inclusion rates into the feed (250 g/ton; PRO250, or 500 g/ton; PRO500), or in the drinking water (25 g/L; PRO-WS), or as a feed synbiotic (250 g probiotic + 250 g/ton prebiotic; SYN), compared to a negative (NC; without additives) and positive control (PC; with antibiotics) diets. The PRO-WS enhanced feed intake (p < 0.05) and tended to improve average daily gain and final body weight (p = 0.14). Broiler gut morphology in the duodenum including the villus height (p = 0.04), villus width (p = 0.05) and crypt depth (p = 0.02) were improved by PRO500. Firmicutes was the most abundant phylum, followed by Bacteroidetes. Streptococcaceae, Lachnoospiraceae, Peptostreptococcaceae, Ruminococcaceae, and Erysipe-lotrichaceae were the top five most abundant families. Antibiotic inclusion in PC reduced microbial beta-diversity and increased similarity compared to probiotic inclusion (p = 0.05). Probiotic inclusion reduced the relative abundance of Bacteroides fragilis, which is a commonly isolated pathogen and is considered as a marker for antimicrobial resistance. Overall, probiotic supplementation via feed or water may potentially improve the production performance of the broiler chickens, and water-soluble probiotics are potentially more effective. Probiotics, especially when added to water, suggest a promising feed additive to support gut microbial maturation and diversity, and may reduce resistant bacteria in broiler chickens. However, it is suggested that the best route for the administration of probiotics be further examined under commercial conditions to find the most effective and practical application method that yields the most consistent results.

The Impact of Bacillus subtilis PB6 and Chromium Propionate on the Performance, Egg Quality and Nutrient Metabolizability of Layer Breeders

The objective of this study was to evaluate the effects of Bacillus subtillis PB6, chromium propionate or a combination of the two on the performance, egg and eggshell quality, nutrient metabolizability and serum biochemistry of layer breeders. White Plymouth Rock and Red Rhodes Island breeder hens at 55 weeks of age were allocated in individual cages using a completely randomized block design with 16 replicates. Hens were fed control, control + probiotic (500 g/ton of Bacillus subtilis PB6), control + CrProp (50 g/ton of chromium propionate) and control + probiotic + CrProp diets from 55 to 70 weeks of age. Productive parameters and eggshell quality as well as cortisol and blood biochemistry were grouped each 28 d as well as for the overall period. The metabolizability of nutrients and energy was determined at 70 weeks of age. In the overall period, hens fed the control + probiotic or control + probiotic + CrProp diets had significantly higher egg production, egg mass, shell percentage, thickness and shell strength. The metabolizability of dry matter, nitrogen and energy increased in hens that were fed the control + probiotic + CrProp diet. In conclusion, diets supplemented with Bacillus subtillis PB6 and chromium propionate resulted in improved productive performance, eggshell quality and nutrient metabolizability of layer breeders, without modifying serum cortisol, albumin and triglycerides.

Caecal microbiota could effectively increase chicken growth performance by regulating fat metabolism

It has been established that gut microbiota influences chicken growth performance and fat metabolism. However, whether gut microbiota affects chicken growth performance by regulating fat metabolism remains unclear. Therefore, seven‐week‐old chickens with high or low body weight were used in the present study. There were significant differences in body weight, breast and leg muscle indices, and cross‐sectional area of muscle cells, suggesting different growth performance. The relative abundance of gut microbiota in the caecal contents at the genus level was compared by 16S rRNA gene sequencing. The results of LEfSe indicated that high body weight chickens contained Microbacterium and Sphingomonas more abundantly (P < 0.05). In contrast, low body weight chickens contained Slackia more abundantly (P < 0.05). The results of H & E, qPCR, IHC, WB and blood analysis suggested significantly different fat metabolism level in serum, liver, abdominal adipose, breast and leg muscles between high and low body weight chickens. Spearman correlation analysis revealed that fat metabolism positively correlated with the relative abundance of Microbacterium and Sphingomonas while negatively correlated with the abundance of Slackia. Furthermore, faecal microbiota transplantation was performed, which verified that transferring faecal microbiota from adult chickens with high body weight into one‐day‐old chickens improved growth performance and fat metabolism in liver by remodelling the gut microbiota. Overall, these results suggested that gut microbiota could affect chicken growth performance by regulating fat metabolism.

Effect of a Potential Probiotic Candidate Enterococcus faecalis-1 on Growth Performance, Intestinal Microbiota, and Immune Response of Commercial Broiler Chickens

The probiotic effect of Enterococcus faecalis-1 (isolated from healthy chickens) on growth performance, immune response, and modulation of the intestinal microbiota of broilers was assessed with a total of 100-day-old commercial Cobb chicks. The chicks were randomly divided into two equal groups. The control group received a basal diet, while the test group received a basal diet and was orally supplied with E. faecalis at a dose of 10⁸ CFU/bird/day. Results showed that E. faecalis-1 supplement significantly (P < 0.05) improved the body weight and feed conversion ratio of treated broilers compared with the control ones. The mortality percentage was reduced in E. faecalis-1-supplemented group. The total IgY serum level was significantly (P < 0.05) increased in broilers receiving E. faecalis-1 supplement (7.1 ± 0.39) compared with the control group (5.8 ± 0.3), while the serum avidin level was significantly (P < 0.05) decreased in E. faecalis-1-supplemented broilers (76 ± 11.1). There was no significant change in the immune response towards avian influenza and Newcastle vaccines in both groups. The total Lactobacillus and Enterococcus counts were significantly (P < 0.05) higher in the cecal contents of broilers given E. faecalis-1 than those that received the control treatment. E. faecalis-1 supplement enhanced the enzyme activities, antioxidant system, and liver functions of treated broilers compared with those in the control group. Collectively, these results showed that E. faecalis-1 could promote growth performance and immunological status and convey beneficial modulation of the cecal microbiota in broilers.

Effective Microorganisms (EM) Improve Internal Organ Morphology, Intestinal Morphometry and Serum Biochemical Activity in Japanese Quails under Clostridium perfringens Challenge

The effect of effective microorganisms (EM) on internal organ morphology, intestinal morphometry, and serum biochemical activity in Japanese quails under Clostridium perfringens challenge was determined. After 30 days of EM addition, one group of quails was orally inoculated with Clostridium perfringens. The second group did not receive EM and was inoculated with C. perfringens. In the gut, EM supplementation reduced the number of lesions, enhanced gut health, and protected the mucosa from pathogenic bacteria. EM showed an anti-inflammatory effect and fewer necrotic lesions in villi. In the internal organs, EM showed a protective effect against a typical lesion of C. perfringens infection. Necrosis and degeneration of the hepatocytes, necrosis of bile ducts, and bile duct proliferation were more severe in the infected group without EM. Morphometric evaluation showed significantly higher villi in the jejunum after EM addition. A greater crypt depth was observed in the C. perfringens group. Biochemical analysis of the blood indicated lower cholesterol on the 12th day of the experiment and between-group differences in total protein, lactate dehydrogenase (LDH), and albumin levels in the EM group. Further studies are needed to improve EM activity against pathologic bacteria as a potential alternative to antibiotics and to develop future natural production systems.

Microbiome analysis reveals gut microbiota alteration in mice with the effect of matrine

Mounting evidence revealed the negative effects of abuse of antibiotic including the induction of decreased immunity and dysbacteriosis. Matrine displayed multiple beneficial effects such as anti-inflammatory, antiviral and antibacterial, but studies of its influence on gut microbiota are still insufficient to report. Here, the present study was conducted to investigate the influence of matrine on the gut microbiota of mice and amoxicillin was used as a positive control. A total of 21 cecal samples were obtained from seven groups for high-throughput sequencing analysis based on V3-V4 variable region of 16S rRNA genes. Results revealed that the diversity and abundance of gut microbiota in mice gradually decreased with the increase of the concentration of amoxicillin, whereas matrine administration did not effect the intestinal microbial community structure. Additionally, amoxicillin and matrine supplementation also caused significant changes in the relative abundance of some intestinal bacteria. Specifically, the ratio of Klebsiella and Corynebacterium_1, Bacteroides and Parasutterella in the amoxicillin treated-group were increased as compared to the control group, whereas Muribaculaceae_unclassified, Alistipes and Lactobacillus were significantly decreased. Conversely, matrine administration significantly increased the proportion of beneficial bacteria such as Ruminiclostridium_9, Lachnospiraceae_NK4A136_group and Ruminococcaceae_unclassified. In conclusion, amoxicillin administration could change the microbial community composition and structure by increasing the proportion of pathogenic to beneficial bacteria, whereas matrine could increase the number of beneficial bacteria. Moreover, this study provides a theoretical basis for finding alternatives to antibiotics to decrease bacterial resistance and intestinal flora imbalance.

Effect of Lactobacillus Species Probiotics on Growth Performance of Dual-Purpose Chicken

Introduction

In-feed probiotics are becoming attractive alternatives to antibiotics in the poultry industry due to the ever-growing strict prohibitions on antibiotic growth promoters (AGP) in animal production.

Methods

The study was conducted to investigate the effects of Lactobacillus paracaseis sparacasei and Lactobacillus rhamnosus on the growth performance of 120 day-olds randomly selected Sasso dual-purpose chicken. They were divided into four groups with two replicates per group and 15 chicks per replicate. The treatments were T₁ (control), T₂ (supplement diet with 4g probiotic), T₃ (supplement diet with 2g probiotic), T₄ (supplement diet with 1g probiotic). The experimental feeding trials were conducted after two weeks adaptation period.

Results

The present findings revealed that the chickens supplemented with Lactobacillus species probiotics during the first week of age have shown higher body weight than control (p < 0.05). The feed intake of week one of T₂ and T₃ were significantly higher (p< 0.05) than the T₁ (control). However, there was no significant difference (p> 0.05) in feed intake in the 2^nd, 3^rd, 4^th, and 5^{t h} weeks of all treatment groups. The present result showed that there was a significant body weight gain (p< 0.05) in all probiotic fed groups than the control group. The highest body weight gain was observed in chickens found in the T4 treatment group. Whereas the body weight gains significantly higher and improved the feed conversion (p<0.05) in the T₂ and T₄ than the T₁ (control). However, the feed conversion ratio was significantly influenced by probiotic inclusion in T₃ as compared to the control group.

Conclusion

Overall, the results suggest that Lactobacillus paracaseis sparacasei and Lactobacillus rhamnosus have a positive effect on the growth performance of broilers.

Assessment of novel probiotic strains on growth, hematobiochemical parameters, and production costs of commercial broilers in Bangladesh

Background and Aim:

The use of antibiotic growth promoters (AGPs) in the poultry industry has raised concern because of their potential harm to human health. Emerging evidence suggests that probiotics are a safer substitute, although little research has explored this in Bangladesh. We recently isolated local bacterial strains with probiotic properties. We aimed to determine their impact on the growth, hematobiochemical parameters, and production costs of broiler chicks relative to that of a commercial probiotic (CP) and AGP.

Materials and Methods:

Day-old male broiler chicks (Cobb 500, n=63) were divided equally into three experimental groups (three replicates per group and seven chicks per replicate). First group was fed a basal diet supplemented with the AGP, ciprofloxacin (CTL group), second group was fed a basal diet supplemented with the CP, Protexin^® (CP group), and the third group was fed a basal diet supplemented with our isolated bacterial strains (study probiotic [SP] group) for 36 days. Body weight was recorded daily, and relative growth rate (RGR), feed conversion ratio (FCR), and organ weights and carcass yields were calculated at the study’s end. Blood obtained on day 36 was used to determine the number of red blood cell (RBC) and white blood cells (WBCs), hemoglobin (Hb) concentration, packed cell volume, erythrocyte sedimentation rate, as well as levels of serum glucose, total and high-density lipoprotein (HDL) cholesterol, and triglycerides (TGs). Total production costs were estimated by summing the variable and fixed costs.

Results:

Chicks in both the CP and SP groups experienced significant decreases in blood glucose levels and significant increases in BW, RGR, FCR, levels of RBC and WBC, Hb concentration, and packed cell volume compared with those in the CTL group (p<0.05 for all). Our data suggested a numerical reduction (p>0.05) in levels of total cholesterol, TGs, and HDL in the SP and CP groups when compared to the CTL group. In addition, both CP and SP treatments resulted in significant (p<0.05) gains in net profit compared with the treatment given to the CTL group.

Conclusion:

Administration of probiotics, either from a commercialized or local source, led to greater improvements in growth, hematological parameters, and net profits of broiler chicks when compared with that of an AGP. This suggests that they are suitable alternatives to the AGPs used in poultry feed and that our isolated strains, in particular, are an ideal option for farmers in Bangladesh.

Study of Probiotic Effects of Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus plantarum 299v Strains on Biochemical and Morphometric Parameters of Rabbits after Obesity Induction

Simple Summary

On the basis of the extensive literature, two main strategies have been used to manipulate intestinal microbial composition and selectively stimulate the growth and activity of certain species, these being the administration of either prebiotics or food supplements containing living bacteria such as probiotics. Several animal studies have indicated that certain probiotics, including Lactobacilli and Bifidobacteria, can suppress body weight gain in rodents, while some probiotics strains have little effect or promote weight gain. The potential anti-obesity effect of probiotics seems to depend on the strains used and the underlying mechanisms, leading to their effects remaining not fully understood. It is in this context that this study was designed to investigate the potential of two probiotics strains, these being Bifidobacterium animalis subsp. lactis BB-12^® and Lactobacillus plantarum 299v^® in rabbits, whereby obesity and metabolic syndrome was first induced in a first experiment, and the animals were then used in a second experiment to test the hypothesis of probiotics effect on biochemical and morphometric parameters. The model of obesity induced by giving a “cafeteria” diet for 14 weeks in this trial demonstrated a change in the biochemical and morphometric parameters investigated in the ITELV2006 rabbit strain. This study revealed that B. animalis subsp. lactis BB-12 and L. plantarum 299v strains could exert beneficial effects in reducing the incidence of obesity and metabolic syndrome in the ITELV2006 rabbit strain.

Abstract

This study aimed first to develop an experimental model of obesity and metabolic syndrome over 14 weeks using a diet called “cafeteria”, which is a high-fat diet, to evaluate its consequences on the biochemical and morphometric parameters in ITELV2006 strain rabbits. Second, the trial aimed to evaluate the effect of two strains of probiotics, these being Bifidobacterium animalis subsp. lactis BB-12^® and Lactobacillus plantarum 299v^®, on the obesity and MetS induced during the first experiment. Overall, the results of the “cafeteria” diet demonstrated significant changes in numerous biochemical and morphometric parameters, reproducing obesity and the main clinical manifestations of the metabolic syndrome in humans. The administration of the two probiotic strains demonstrated an impact on certain parameters of obesity and induced MetS. This study makes it possible to conclude that probiotics could be useful in the treatment of obesity and metabolic syndrome of rabbits, but in a dependent manner. Furthermore, this study evidenced the importance of selecting specific probiotic strains and dosages to achieve desirable results on rabbits or other species.

Potency of probiotic on broiler growth performance and economics analysis

The study was undertaken to know the economic analysis in broilers fed probiotic containing Lactobacillus casei and Lactobacillus rhamnosus supplementation in lieu of antibiotic growth promoters (AGP) to feed conversion ratio (FCR) and body weight (BW). The treatments were T0: control, T1: 0.01 g AGP/kg feed, T2: 0.05 g/ kg feed, T3: 0.1 g/ kg feed, T4: 0.025 g probiotic/litre drinking water; T5: 0.05 g probiotic/liter drinking water. Data analysis was carried out using the Analysis of Variance (ANOVA) method, business analysis was held out by XLSTAT then analyzing descriptively. The results indicated that there was a significant difference among the treatments. Probiotic administration of T2, T3, T4 and T5 could increase broiler's body weight and improve feed conversion ratio. The higher production performance and most profitable economic analysis was obtained with the addition of 0.025 g probiotic/litre (T4), which had the best results in a Break Even Point and Return Cost Ratio. It could be concluded that supplementation of 0.025 g probiotic/litre drinking water indicates the improve growth performance and profits in broiler.

Physiological parameter values for physiologically based pharmacokinetic models in food-producing animals. Part II: Chicken and turkey

Physiologically based pharmacokinetic (PBPK) models are growing in popularity due to human food safety concerns and for estimating drug residue distribution and estimating withdrawal intervals for veterinary products originating from livestock species. This paper focuses on the physiological and anatomical data, including cardiac output, organ weight, and blood flow values, needed for PBPK modeling applications for avian species commonly consumed in the poultry market. Experimental and field studies from 1940 to 2019 for broiler chickens (1-70 days old, 40 g - 3.2 kg), laying hens (4-15 months old, 1.1-2.0 kg), and turkeys (1 day-14 months old, 60 g -12.7 kg) were searched systematically using PubMed, Google Scholar, ProQuest, and ScienceDirect for data collection in 2019 and 2020. Relevant data were extracted from the literature with mean and standard deviation (SD) being calculated and compiled in tables of relative organ weights (% of body weight) and relative blood flows (% of cardiac output). Trends of organ or tissue weight growth during different life stages were calculated when sufficient data were available. These compiled data sets facilitate future PBPK model development and applications, especially in estimating chemical residue concentrations in edible tissues to calculate food safety withdrawal intervals for poultry.

The Effect of Ag Nanoparticles and Multimicrobial Preparation as Factors Stabilizing the Microbiological Homeostasis of Feed Tables for Cornu aspersum (Müller) Snails on Snail Growth and Quality Parameters of Carcasses and Shells

Simple Summary

The farming of snails, unlike that of large farm animals, requires less space and financial resources, and snails are not as demanding. In field husbandry conditions, snails have access to green forage and are given concentrated mixtures on feed tables. In this maintenance system, it is important to carry out treatments stabilizing the microbiological balance of feed tables, where snail feces and feed refusals accumulate. This study analyzed the effect of paint with silver nanoparticles (nano-Ag) or a multimicrobial preparation applied to feed tables on the microbiological composition of the feed table environment, the growth and mortality of snails, and parameters assessing the quality of carcasses and snail shells. Results showed that the use of nano-Ag paint reduced the growth of bacteria, while the multimicrobial preparation reduced mold and yeast. Spraying feed tables with the multimicrobial preparation had a better effect on the growth of snails, while the use of nano-Ag paint reduced the mortality of the animals. The factors used did not have a negative effect on the quality of shells. The snails that had contact with nano-Ag paint showed a higher content of Ag in the carcasses and a greater degree of lipid peroxidation.

Abstract

The aim of this research was to evaluate the effect of Ag nanoparticles (nano-Ag) used in the paint covering feed tables or a multimicrobial preparation applied to feed tables on the microbiological composition of the feed table environment, the growth and mortality of snails, and selected parameters for assessing the quality of carcasses and snail shells. The research was carried out in a farm of Cornu aspersum (Müller) snails. In the control (K) group, paint without nano-Ag was used. In two other groups (N-Ag and N-Ag + effective microorganisms (EM)), the feed tables were covered with the same paint as in the control group but with the addition of 100 mg/L of nano-Ag it (N-Ag group). Additionally, multimicrobial preparation (EM Bokashi^®) at a concentration of 10% was spread on the tables in the N-Ag + EM group. In the last group (EM), the feed tables were covered with paint without nano-Ag, and only multimicrobial preparation was applied at a concentration of 10%. During the tests, the body weight of snails was measured three times, and swab samples were taken from the feed tables for the examination of microbiological composition. At the end of the experiment, the snails were killed, and the weight of the carcass and the size of the shell were measured. The content of Ag and the degree of lipid oxidation (thiobarbituric acid reactive substances (TBARS)) in the carcasses were analyzed, and the content of Ca and the crushing strength of the shells were determined. In the N-Ag and N-Ag + EM groups, a significant reduction in the total number of bacteria, fecal streptococci, and Escherichia coli was found, while there was also a reduction in mold and fungi in the N-Ag + EM and EM groups. In the K and EM groups, the mortality of animals was higher than in the nano-Ag groups. In subsequent weight checks, the highest body weight was found in the EM group and the lowest in the N-Ag and N-Ag + EM groups. In addition, the carcass weight and shell size in the N-Ag group was significantly lower compared to the K and EM groups. In the N-Ag and N-Ag + EM groups, a higher Ag content in the carcasses and a greater degree of lipid peroxidation were found. The Ca content of the shells was the highest in the N-Ag group, and the hardness of shells was the highest in the N-Ag and N-Ag + EM groups.

Effect of Bacillus velezensis to substitute in-feed antibiotics on the production, blood biochemistry and egg quality indices of laying hens

BACKGROUND

The excessive use of antibiotics in the livestock feed industry caused inevitable side effects of microbial resistance. Besides this residual antibiotics in animal-derived foodstuff imposed serious health problems for humans. So this study aimed to investigate the potential use of Bacillus velezensis to substitute antibiotics for poultry production. A total of 468, 49-week-old Hy-Line Brown chickens, were randomly divided into four groups the control group (regular diet), experiment group I (0.1% B. veleznesis), experiment group II (0.2% B. veleznesis), and antibiotic group (50 mg/kg flavomycin), with three replicates per group and trial period consisted on 42 days.

RESULTS

The results showed that, compared with the control group, the average egg production rate and daily feed intake of experimental groups I and II increased significantly (P < 0.05), while the average egg weight was increased in experimental group II as compared to (I) (P < 0.01). The feed conversion ratio was decreased (P > 0.05) in group (II) Egg quality parameters such as yolk weight of the experimental group II was increased, but that of the antibiotic group and experiment group I was decreased, neither significant (P > 0.05). Moreover, the eggshell strength, yolk color, albumen height, and Haugh unit were significantly increased (P < 0.05). Compared with the control group, probiotic groups can increase the progesterone and motilin (P > 0.05) but decrease the secretin and cholecystokinin in the blood plasma (P > 0.05).

CONCLUSIONS

This study suggested that B. velezensis can substitute in-feed-antibiotics and improved most of the study parameters significantly. Which suggested that B. velezensis has potential future application value to replace the feed antibiotics.

Dietary Supplementation of Probiotic Lactobacillus acidophilus Modulates Cholesterol Levels, Immune Response, and Productive Performance of Laying Hens

Simple Summary

Chicken eggs provide a considerable source of high-quality nutrients for human food and health. However, egg consumption may harm some people for its high contents of cholesterol and association with cardiovascular disease risk. Therefore, we investigated the possible effect of using Lactobacillus acidophilus (LA) as a probiotic additive in the laying hens’ diets on lowering egg-yolk cholesterol and also evaluated the immune responses and the productive performance of laying hens. The obtained results display the ability of LA, when supplemented in hen diets, to decrease the plasma triglycerides and cholesterol levels and the liver and egg yolk cholesterols in the hen. The beneficial effects of LA were also explored on some important humoral and cell-mediated immune responses in the laying hens. These positive effects led to an improvement in the productive performance of laying hens. Therefore, dietary LA supplementation could be recommended as a nutritional strategy for commercial lower-cholesterol egg production in addition to positive impacts on the performance and health of laying hens.

Abstract

This study examines the effect of dietary supplementation with Lactobacillus acidophilus (LA) on the cholesterol levels, immune response, and productive performance of laying hens. A total of 216, 40-week-old, commercial Hy-Line brown chicken layers were randomly assigned into four treatment groups (18 birds × three replicates per group) and fed diet supplemented with 0 (control), 1 × 10⁹, 21 × 10⁹, and 31 × 10⁹ colony forming units (CFUs) of Lactobacillus acidophilus (LA) per kg of feed for six consecutive weeks. Results show that plasma triglycerides, low-density lipoprotein (LDL) and total cholesterols became lesser, while high-density lipoprotein (HDL) cholesterol became higher in LA-supplemented groups compared to the control. In addition, a significant reduction occurred in the liver and egg yolk cholesterol by LA supplementation. Moreover, the immunological parameters including antibody titer against sheep red blood cells (SRBCs), phytohemagglutinin (PHA)-wattle swelling test, and T- & B-lymphocyte proliferation were enhanced in laying hens supplemented with LA compared to the control hens. While the heterophil to lymphocyte (H/L) ratio decreased with LA supplementation, indicating low stress conditions in the treated hens. These positive effects for LA were further reflected on the productive performance of laying hens and improved egg production, egg weight, egg mass, and feed efficiency. Our findings indicate that LA probiotic could be recommended in laying hens’ diets for lowering egg yolk cholesterol with positive impacts on health and performance.

Dietary corn-resistant starch suppresses broiler abdominal fat deposition associated with the reduced cecal Firmicutes

This study investigated the effects of dietary corn-resistant starch on lipid metabolism of broilers and its potential relationship with cecal microbiota modulation. A total of three hundred twenty 1-day-old male broilers were randomly assigned into 5 dietary treatments: 1 normal corn–soybean (NC) diet, 1 corn–soybean–based diet supplementation with 20% corn starch (CS), and 3 corn–soybean–based diets supplementation with 4, 8, and 12% corn resistant starch (RS) (identified as 4%RS, 8%RS, and 12%RS, respectively). Each group had 8 replicates with 8 broilers per replicate. The experiment lasted 21 d. The results showed that the abdominal fat percentage were lower in birds from 8%RS and 12%RS groups (0.75 and 0.58%, respectively) than those from NC and CS groups (1.20 and 1.28%, respectively; P < 0.05). The birds from 8%RS and 12%RS groups exhibited lower concentrations of blood triglyceride and nonestesterified fatty acid than those in the NC and CS groups (P < 0.05). Moreover, birds fed diets supplementation with 12% RS decreased the relative mRNA expressions of peroxisome proliferator-activated receptor gamma, ATP citrate-lyase, fatty acid synthase, and acetyl-CoA carboxylase in liver, and glycerol-3-phosphate acyltransferase in abdominal adipose tissue (P < 0.05). Microbiota analysis revealed that birds fed diets supplementation with 8 and 12% RS decreased the abundance of cecal Firmicutes by 23.08 and 20.47% and increased the proportion of Bacteroidetes by 24.33 and 21.92%, respectively, compared with the NC group (P < 0.05). In addition, correlation analysis revealed that many Firmicutes members had highly positive relationship with blood lipid levels and fat storage capacity, which might contribute to the lower abdominal fat phenotype. Overall, broilers receiving diets containing a higher concentration of RS harbor less Firmicutes, which decreased liver fatty acid synthesis and suppress abdominal fat deposition of birds during the starter phase. These findings provide a profound understanding about the relationship between gut microbial composition and lipid metabolism in broilers.