Synbiotic from Autochthonous Probiotic – An Alternate to Antibiotics in Controlling Calf Diarrhoea
Dr.M.Srivani*, Dr.M.Muralidhar, Dr.K.Lakshmikavitha, Dr.Ch.V.Seshaiah and J.Srilakshmi
*Associate Professor & PI
DST SERB Research Project
Department of Veterinary Microbiology
NTR College of Veterinary Science, Gannavaram, Krishna District, AP
Calf diarrhoea is a major cause of high morbidity and mortality in calves, results in economic loss for the dairy producers in India. Several etiological agents are responsible for calf diarrhoea of which E. coli was recognised as the leading cause. Several earlier studies indicated that calves with diarrhoea often have small intestinal overgrowth with Escherichia coli bacteria, regardless of the inciting cause for the diarrhoea, and 30% of systemically ill calves with diarrhoea have bacteraemia, predominantly because of E. coli.
In neonatal calves, immediately after birth colonization of the GI tract begins from the external environment. The natural flora of the gut community protects the host against invading microorganisms and helps to maintain homeostasis, including immune regulation. Disruptions of gut flora occur due to dietary shifts or infection, leading to disease.
Antibiotics have been used to prevent and control intestinal infections in young calves for many years. However, indiscriminate usage of antibiotics to treat the diarrhoea has led to increased multidrug resistance in animals, animal products, and increased emergence of drug-resistant bacteria in human beings. Therefore, there is a need to use alternatives to antibiotics in prevention and control of calf diarrhoea that would positively influence the composition of intestinal microbiota and improve livestock health.
Several strategies have been used to modulate the composition and function of the gut microbiota, of which supplementation of probiotic, and the use of non-digestible dietary substrates such as prebiotics is a promising strategy to maintain gut health. Probiotics are defined as “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host”. The probiotics have beneficial effects like maintenance of intestinal homeostasis, competitive elimination of pathogens, production of antimicrobial compounds like bacteriocins, promotion of gut barrier function and immune modulation through build up of macrophages, natural killer (NK) cells, antigen-specific cytotoxic T-lymphocytes and the release of various cytokines in a strain-specific and dose-dependent manner. Prebiotics are nondigestible food ingredients which when consumed in sufficient amounts selectively stimulate the growth and activity of one or a limited number of microbes in the gut, including the probiotic strains. Most commonly known prebiotics are inulin, fructooligosaccharide (FOS), galactooligosaccharide (GOS), mannanoligosaccharide (MOS).
The potential probiotic strains that are popular now a days belongs to different Genera like Lactobacillus, Bifidobacterium, Saccharomyces or Bacillus species which inhibit the colonization of pathogenic bacteria and brings about the stabilization of gut microbiota. Among the probiotic species, Lactobacillus sp. are most widely used probiotic for the calves to prevent neonatal diarrhoea. Lactobacillus is a Gram-positive facultative anaerobic cocci or rod shaped bacteria. They produce lactic acid, hydrogen peroxide and bacteriocins as the major metabolic end products of carbohydrate fermentation which create an acidic, unfavourable environment for pathogenic organisms. Lactobacilli are generally recognized as safe due to their ubiquitous appearance in food and their contribution to the healthy microbiota of animal and human mucosal surfaces. Due to their beneficial and non-pathogenic effects, Lactobacilli are considered to be potential probiotics.
Selection of suitable probiotic strain is important, because the efficacy of probiotic is host specific. The probiotic bacterial species that are autochthonous to the ecosystem that they belong has high host‐species specificity, which is essential for better adhesion and efficacy compared to the probiotics from different sources. The adherence of pathogens to the intestinal niches decreases with competitive inhibition by probiotic species in the intestinal ecosystem. The efficacy of probiotic species was further increased if they combined with fermentable non-digestible food ingredients called prebiotics. The combination of probiotic and prebiotic is called “synbiotic” which is defined as a mixtures of probiotics and prebiotics that beneficially affect the host by improving the survival and implantation of live microbial dietary supplements in the gastrointestinal tract, by selectively stimulating the growth and/or by activating the metabolism of one or a limited number of health-promoting bacteria, thus improving host welfare. The synbiotics are of two types i.e. complementary synbiotic which comprises a probiotic and a prebiotic, that together confers one or more health benefits but do not require co-dependent functions, while these in a synergistic synbiotic work in co-dependent manner.
The prebiotics were selectively fermented by the probiotic strains by secretion of a wide range of specific enzymes such as polysaccharidases, aminopeptidases, proteases, glycosidases, glycanases for their growth. However, the pahogenic strains such as, Salmonella spp., E. coli, and Clostridial sp. are unable to use these substances. Further, the prebiotics can be recognized by toll-like receptors and NOD-like receptors, both are pattern recognition receptors present in immune membrane cells. This recognition will modulate the innate immune response by inducing an overexpression of innate immune cells such as epithelial cells, macrophages, mast and dendritic cells which eventually helps in the better treatment of several diseases. Therefore, synbiotics are more effective in controlling the diarrhoea. Further, the synbiotics also increase the level of digestive enzymes such as lactase, lipase, sucrase and isomaltase in the animals, results increased digestibility.
A species specific synbiotic against multi drug resistance E. coli was developed for buffalo calves under DST SERB research project at the Department of Veterinary Microbiology, NTR College of Veterinary Science, Gannavaram. The synbiotic was developed with different species of autochthonous lactobacilli isolated from healthy buffalo calves and mannanoligosaccharide as prebiotic. The synbiotic was tested in experimental neonatal buffalo calves harbouring multidrug resistant E. coli. The results of this study revealed that synbiotic was significantly reduced the multidrug resistant E. coli in buffalo calves and also prevent diarrhoea in calves. The synbiotic was also tested for its therapeutic potential in diarrhoeic buffalo calves under field conditions which effectively controlled diarrhoea and the faecal consistence score was changed with in two to three days.
Synbiotic formulations prepared from autochthonous lactobacillus species in this study are proven as potential alternate to antibiotics in controlling the calf diarrhoea. The complementary or synergic action of synbiotic is superior than either probiotic or prebiotic alone against pathogenic organisms. Although various products with probiotic, prebiotics and synbiotic are usually available in food and supplement formats, further research is required to formulate various synbiotics from species specific autochthonous probiotic with suitable prebiotic against specific diseases in livestock to minimise antimicrobial usage in farm animals.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4462921/
