Markowiak and Śliżewska Gut Pathog (2018) 10:21 https://doi.org/10.1186/s13099-018-0250-0 Gut Pathogens REVIEW Open Access The role of probiotics, prebiotics and synbiotics in animal nutrition Paulina Markowiak* and Katarzyna Śliżewska* Abstract Along with the intensive development of methods of livestock breeding, breeders’ expectations are growing concern- ing feed additives that would guarantee such results as accelerating growth rate, protection of health from patho- genic infections and improvement of other production parameters such as: absorption of feed and quality of meat, milk, eggs. The main reason for their application would be a strive to achieve some benefcial efects comparable to those of antibiotic-based growth stimulators, banned on 01 January 2006. High hopes are being associated with the use of probiotics, prebiotics and synbiotics. Used mainly for maintenance of the equilibrium of the intestinal micro- biota of livestock, they turn out to be an efective method in fght against pathogens posing a threat for both animals and consumers. This paper discusses defnitions of probiotics, prebiotics and synbiotics. Criteria that have to be met by those kinds of formulas are also presented. The paper ofers a list of the most commonly used probiotics and prebi- otics and some examples of their combinations in synbiotic formulas used in animal feeding. Examples of available study results on the efect of probiotics, prebiotics and synbiotics on animal health are also summarised. Keywords: Animal health, Prebiotics, Probiotic bacteria, Synbiotics Background quality and safety of meat, while taking animal welfare It is estimated that by 2050 the number of people in the and respect for the natural environment into account. world will reach 9 billion. Constant growth of the human Both animal feed and feed supplements have to meet population is inseparably associated with a growing some strict criteria, without a simultaneous rise of ani- demand for food of plant and animal origin. For that rea- mal breeding costs. In the past, antibiotics and other son, scientists are looking for solutions allowing intensi- medicinal products had been broadly used, mainly in fcation of food production, with simultaneous reduction order to modify the alimentary microbiota and to boost of production costs, and in compliance with high stand- productivity and animal growth. Long-term use of those ards of quality and safety (for both people and the envi- substances has led to development of drug-resistant ronment). Types of used feed additives afect animal microorganisms, posing a threat to consumers’ health health and increased production of high quality meat, and exerting a negative efect on the environment [1, 2]. eggs, milk and fsh. Animal production is inseparable As a result, on 1 January 2006 the use of antibiotic-based from nutrition and health of the consumer, and animal growth stimulators was banned in the European Union. intestinal pathogens, such as Campylobacter, Salmonella, Terefore, alternative natural substances ensuring simi- Listeria and Yersinia, are a direct source of food contami- lar efects have been sought. Te Regulation (EC) No. nation and a cause of zoonoses. Terefore, new methods 1831/2003 of the European Parliament and of the Council of animal breeding are introduced, aimed at increased of 22 September 2003 on additives used in animal nutri- tion, mentions probiotics and prebiotics among other substances, whereas in the Regulation (EC) No. 767/2009 *Correspondence: [email protected]; on the placing on the market and use of feed, this aspect [email protected] was not changed. High hopes are also evoked in relation Department of Biotechnology and Food Sciences, Institute to the synergistic combination of both these components, of Fermentation Technology and Microbiology, Lodz University of Technology, ul. Wólczańska 171/173, 90‑924 Lodz, Poland namely the so-called synbiotics. © The Author(s) 2018. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creat​iveco​mmons​.org/licen​ses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creat​iveco​mmons​.org/ publi​cdoma​in/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Markowiak and Śliżewska Gut Pathog (2018) 10:21 Page 2 of 20 Probiotics poultry. Tat type of formulas may contain one or more Te term “probiotic” comes from two Greek words (“pro” selected strains of microorganisms, and depending on and “bios”) and it means “for life”. Te frst concept of the species and age of host animals they may be admin- probiotics was probably suggested in 1907 by Mechnikov istered as a powder, suspension, capsules, pellet, gel or [3], who noted that bacteria may have a benefcial infu- paste. Tey are used periodically or constantly, directly ence on the natural intestinal microfora. Te term of per os or as an additive to feed and premixes. Probiotic “probiotic” was probably invented by Ferdinand Vergin, cultures used as feed additives must meet some specifc who in his paper of 1954 entitled “Anti- und Probiotika” criteria. compared a harmful efect of antibiotics and other anti- microbial agents on the intestinal microbiota with a ben- Selection criteria and requirements for probiotic strains efcial efect (“probiotica”) of selected bacteria [4]. With Assessment of the safety of probiotic strains is necessary time, the defnition of probiotic was largely modifed for the optimization of their use. However, it is not an (Table 1). easy task [20]. Te mode of action of probiotics as micro- Te current defnition formulated in 2002 by FAO and bial additives to feed is not fully understood. By adhering WHO working group experts states that probiotics are to the alimentary tract probiotic organisms may survive “live strains of strictly selected microorganisms which, difcult conditions, and ofer a benefcial efect on the when administered in adequate amounts, confer a health stability and protection of the intestinal ecosystem. Tey beneft on the host” [15]. Te defnition was in 2013 also infuence the course of digestive and metabolic pro- maintained by the International Scientifc Association for cesses and the immunological response. Consequently, Probiotics and Prebiotics (ISAPP). Te term “probiotic’ is properties of probiotics lead to improved health of ani- reserved for formulas or products that meet some strictly mals, increased productivity [21], and improved immu- defned criteria. Te most important of these criteria nity of the host [22]. include: an appropriate count of viable cells, a benefcial Te immunomodulatory mechanism action of probiot- efect on a host’s health (which may also involve stimu- ics involved in animal health and diseases is particularly lation of growth), and a benefcial efect on the function important and is based on innate or adaptive immune of the alimentary tract. Efcacy of probiotic preparations system. Te gastro-intestinal lumen contains essential depends on numerous factors. For that reason proper nutrients and benefcial microorganisms, but also patho- selection of bacterial strains and application of a cor- gen microorganisms, toxins, and some foreign antigens rect dose are highly important. Due to their benefcial [23, 24]. Epithelial cells in the GIT mucosa create a selec- efect on health and stimulation of growth, probiotics are tively permeable barrier between the lumen environment broadly used in animal feeds, particularly for pigs and and the internal body tissues [25]. Tis barrier is the frst Table 1 Defnitions of probiotics Year Defnitions 1965 A substance secreted by one microorganism which stimulates the growth of another [5] 1971 Tissue extracts which stimulate microbial growth [6] 1974 Organisms and substances that contribute to intestinal microbial balance [7] 1989 Live microbial feed supplement which benefcially afects the host animal by improving microbial balance [8] 1992 Viable mono- or mixed culture of live microorganisms which, applied to animals or man, have a benefcial efect on the host by improving the properties of the indigenous microfora [9] 1996 A live microbial culture or cultured dairy product that benefcially infuences the health and nutrition of the host [10] 1996 Living microorganisms which, upon ingestion in certain numbers, exert health benefts beyond inherent basic nutrition [11] 1998 Living microorganisms that on ingestion in certain numbers exert health benefts beyond inherent basic nutrition [12] 1999 A microbial dietary adjuvant that benefcially afects the host physiology by modulating mucosal and systemic immunity, as well as improving nutritional and microbial balance in the intestinal tract [13] 2001 A preparation of or a product containing viable, defned microorganisms in sufcient numbers, which alter the microfora (by implantation or colonization) in a compartment of the host and by that exert benefcial health efect in this host [14] 2002 Live strains of strictly selected microorganisms which, when administered in adequate amounts, confer a health beneft on the host [15] 2004 Preparation of viable microorganisms that is consumed by humans or other animals with the aim of inducing benefcial efects by qualitatively or quantitatively infuencing