Bacillus spp. Probiotic Strains as a Potential Tool for Limiting the Use of Antibiotics, and Improving the Growth and Health of Pigs and Chickens.

Diana Luise,Sara Virdis,Paolo Trevisi,Lena Raff,Paolo Bosi,Laura Amatucci

doi:10.3389/fmicb.2022.801827

Diana Luise, Sara Virdis + Show 4 more

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https://doi.org/10.3389/fmicb.2022.801827

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Abstract

The pressure to increasingly optimize the breeding of livestock monogastric animals resulted in antimicrobials often being misused in an attempt to improve growth performance and counteract diseases in these animals, leading to an increase in the problem of antibiotic resistance. To tackle this problem, the use of probiotics, also known as direct in-feed microbials (DFM), seems to be one of the most promising strategies. Among probiotics, the interest in Bacillus strains has been intensively increased in recent decades in pigs and poultry. The aim of the present review was to evaluate the effectiveness of Bacillus strains as probiotics and as a potential strategy for reducing the misuse of antibiotics in monogastric animals. Thus, the potential modes of action, and the effects on the performance and health of pigs (weaning pigs, lactation and gestation sows) and broilers are discussed. These searches yielded 131 articles (published before January 2021). The present review showed that Bacillus strains could favor growth in terms of the average daily gain (ADG) of post-weaning piglets and broilers, and reduce the incidence of post-weaning diarrhea in pigs by 30% and mortality in broilers by 6–8%. The benefits of Bacillus strains on these parameters showed results comparable to the benefit obtained by the use of antibiotics. Furthermore, the use of Bacillus strains gives promising results in enhancing the local adaptative immune response and in reducing the oxidative stress of broilers. Fewer data were available regarding the effect on sows. Discordant effects have been reported regarding the effect on body weight (BW) and feed intake while a number of studies have supported the hypothesis that feeding probiotics to sows could benefit their reproductive performance, namely the BW and ADG of the litters. Taken all the above-mentioned facts together, this review confirmed the effectiveness of Bacillus strains as probiotics in young pigs and broilers, favoring their health and contributing to a reduction in the misuse of direct in-feed antibiotics. The continuous development and research regarding probiotics will support a decrease in the misuse of antibiotics in livestock production in order to endorse a more sustainable rearing system in the near future.

Highlights

Livestock monogastric species, including swine and poultry, are the main sources of meat; they are, at the same time, the main livestock species reared under intensive conditions (Eurostat, 2022)
The present review shows that Bacillus strains applied as potential probiotics have been extensively studied in monogastric livestock species
The passage from a mono-strain approach to a multi specie/multi-strain approach to exploit the synergistic capacity among different strains to face the complex issue of replacing the antibiotics used both in the prophylaxis or as growth promoters is evident

Summary

Introduction

Livestock monogastric species, including swine and poultry, are the main sources of meat; they are, at the same time, the main livestock species reared under intensive conditions (Eurostat, 2022). The European Union has included this issue in the main points of the farm to fork concept and, in the near future, the European Commission will take action to reduce the overall sales of antimicrobials for livestock animals in order to achieve a 50% reduction by 2030 (European Commission, 2020). To tackle this issue, researchers, together with the stakeholders involved in livestock production, have been called upon to identify sustainable solutions to replace and reduce the misuse of antibiotics in livestock. Probiotics have been extensively associated with an improvement in human and animal health in many different ways; namely, having a positive effect on gut immunity by regulating the composition and metabolism of gut microbes, improving the digestion and absorption of nutrients and inhibiting the potential pathogenic bacteria, regulating intestinal disease (Ding S. et al, 2021; Savitri, 2021)

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