Studies investigating the role that complex microbiotas associated with animals and humans play in health and wellbeing have been greatly facilitated by advances in DNA sequencing technology. Due to ...the still relatively high sequencing costs and the expense of establishing and running animal trials and collecting clinical samples, most of the studies reported in the literature are limited to a single trial and relatively small numbers of samples. Results from different laboratories, investigating similar trials and samples, have often produced quite different pictures of microbiota composition. This study investigated batch to batch variations in chicken cecal microbiota across three similar trials, represented by individually analysed samples from 207 birds. Very different microbiota profiles were found across the three flocks. The flocks also differed in the efficiency of nutrient use as indicated by feed conversion ratios. In addition, large variations in the microbiota of birds within a single trial were noted. It is postulated that the large variability in microbiota composition is due, at least in part, to the lack of colonisation of the chicks by maternally derived bacteria. The high hygiene levels maintained in modern commercial hatcheries, although effective in reducing the burden of specific diseases, may have the undesirable effect of causing highly variable bacterial colonization of the gut. Studies in humans and other animals have previously demonstrated large variations in microbiota composition when comparing individuals from different populations and from different environments but this study shows that even under carefully controlled conditions large variations in microbiota composition still occur.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Identification of bacteria associated with desirable productivity outcomes in animals may offer a direct approach to the identification of probiotic bacteria for use in animal production. We ...performed three controlled chicken trials (n = 96) to investigate caecal microbiota differences between the best and poorest performing birds using four performance measures; feed conversion ratio (FCR), utilization of energy from the feed measured as apparent metabolisable energy, gain rate (GR), and amount of feed eaten (FE). The shifts in microbiota composition associated with the performance measures were very different between the three trials. Analysis of the caecal microbiota revealed that the high and low FCR birds had significant differences in the abundance of some bacteria as demonstrated by shifts in microbiota alpha and beta diversity. Trials 1 and 2 showed significant overall community shifts, however, the microbial changes driving the difference between good and poor performers were very different. Lachnospiraceae, Ruminococcaceae, and Erysipelotrichaceae families and genera Ruminococcus, Faecalibacterium and multiple lineages of genus Clostridium (from families Lachnospiraceae, Ruminococcaceae, and Erysipelotrichaceae) were highly abundant in good FCR birds in Trial 1. Different microbiota was associated with FCR in Trial 2; Catabacteriaceae and unknown Clostridiales family members were increased in good FCR and genera Clostridium (from family Clostridiaceae) and Lactobacillus were associated with poor FCR. Trial 3 had only mild microbiota differences associated with all four performance measures. Overall, the genus Lactobacillus was correlated with feed intake which resulted in poor FCR performance. The genus Faecalibacterium correlated with improved FCR, increased GR and reduced FE. There was overlap in phylotypes correlated with improved FCR and GR, while different microbial cohorts appeared to be correlated with FE. Even under controlled conditions different cohorts of birds developed distinctly different microbiotas. Within the different trial groups the abundance of certain bacterial groups correlated with productivity outcomes. However, with different underlying microbiotas there were different bacteria correlated with performance. The challenge will be to identify probiotic bacteria that can reliably deliver favorable outcomes from diverse microbiotas.
Unravelling the mechanisms of how antibiotics influence growth performance through changes in gut microbiota can lead to the identification of highly productive microbiota in animal production. Here ...we investigated the effect of zinc bacitracin and avilamycin on growth performance and caecal microbiota in chickens and analysed associations between individual bacteria and growth performance. Two trials were undertaken; each used 96 individually caged 15-day-old Cobb broilers. Trial 1 had a control group (
n =
48) and a zinc bacitracin (50 ppm) treatment group (
n =
48). Trial 2 had a control group (
n =
48) and an avilamycin (15 ppm) treatment group (
n =
48). Chicken growth performance was evaluated over a 10-day period, and caecal microbiota was characterised by sequencing of bacterial 16S rRNA gene amplicons. Avilamycin produced no effect on growth performance and exhibited little significant disturbance of the microbiota structure. However, zinc bacitracin reduced the feed conversion ratio (FCR) in treated birds, changed the composition and increased the diversity of their caecal microbiota by reducing dominant species. Avilamycin only produced minor reductions in the abundance of two microbial taxa, whereas zinc bacitracin produced relatively large shifts in a number of taxa, primarily
Lactobacillus
species. Also, a number of phylotypes closely related to lactobacilli species were positively or negatively correlated with FCR values, suggesting contrasting effects of
Lactobacillus
spp. on chicken growth performance. By harnessing such bacteria, it may be possible to develop high-productivity strategies in poultry that rely on the use of probiotics and less on in-feed antibiotics.
The majority of chicken microbiota studies have used the ceca as a sampling site due to the specific role of ceca in chicken productivity, health and wellbeing. However, sampling from ceca and other ...gastrointestinal tract sections requires the bird to be sacrificed. In contrast, fecal sampling does not require sacrifice and thus allows the same bird to be sampled repeatedly over time. This is a more meaningful and preferred way of sampling as the same animals can be monitored and tracked for temporal studies. The commonly used practice of selecting a subset of birds at each time-point for sacrifice and sampling introduces added variability due to the known animal to animal variation in microbiota.
Cecal samples and fecal samples via cloacal swab were collected from 163 birds across 3 replicate trials. DNA was extracted and 16S rRNA gene sequences amplified and pyrosequenced to determine and compare the phylogenetic profile of the microbiota within each sample. The fecal and cecal samples were investigated to determine to what extent the microbiota found in fecal samples represented the microbiota of the ceca. It was found that 88.55% of all operational taxonomic units (OTUs), containing 99.25% of all sequences, were shared between the two sample types, with OTUs unique for each sample type found to be very rare. There was a positive correlation between cecal and fecal abundance in the shared sequences, however the two communities differed significantly in community structure, represented as either alpha or beta diversity. The microbial populations present within the paired ceca of individual birds were also compared and shown to be similar.
Fecal sample analysis captures a large percentage of the microbial diversity present in the ceca. However, the qualitative similarities in OTU presence are not a good representation of the proportions of OTUs within the microbiota from each sampling site. The fecal microbiota is qualitatively similar to cecal microbiota but quantitatively different. Fecal samples can be effectively used to detect some shifts and responses of cecal microbiota.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Analysis of model systems, for example in mice, has shown that the microbiota in the gastrointestinal tract can play an important role in the efficiency of energy extraction from diets. The study ...reported here aimed to determine whether there are correlations between gastrointestinal tract microbiota population structure and energy use in chickens. Efficiency in converting food into muscle mass has a significant impact on the intensive animal production industries, where feed represents the major portion of production costs. Despite extensive breeding and selection efforts, there are still large differences in the growth performance of animals fed identical diets and reared under the same conditions. Variability in growth performance presents management difficulties and causes economic loss. An understanding of possible microbiota drivers of these differences has potentially important benefits for industry. In this study, differences in cecal and jejunal microbiota between broiler chickens with extreme feed conversion capabilities were analysed in order to identify candidate bacteria that may influence growth performance. The jejunal microbiota was largely dominated by lactobacilli (over 99% of jejunal sequences) and showed no difference between the birds with high and low feed conversion ratios. The cecal microbial community displayed higher diversity, and 24 unclassified bacterial species were found to be significantly (<0.05) differentially abundant between high and low performing birds. Such differentially abundant bacteria represent target populations that could potentially be modified with prebiotics and probiotics in order to improve animal growth performance.
Prebiotics selectively stimulate the growth of beneficial bacteria within the gastrointestinal tract, and have been investigated in human and animal studies for their capacity to improve intestinal ...health.
We investigated the prebiotics fructo-oligosaccharide (FOS), galacto-oligosaccharide (GOS), and mannan-oligosaccharide (MOS) for their potential to alleviate intestinal damage in rats.
Female Dark Agouti rats (6–8 wk old, 110–150 g) were allocated to 1 of the following treatment groups (n = 8/group): saline/water, saline/FOS, saline/GOS, saline/MOS, 5-fluorouracil (5FU)/water, 5FU/FOS, 5FU/GOS, and 5FU/MOS. Rats were pretreated with either 5% GOS, MOS, or FOS or vehicle (water) from day −12 to day 0. On day 0, rats received a single intraperitoneal injection of saline or 5FU. Metabolic data were recorded daily and all rats were killed on day 3. Histopathology was quantified in hematoxylin and eosin–stained sections. Intestinal sucrase and myeloperoxidase activity were quantified by biochemical assay. Fecal SCFAs—acetic, propionic, and butyric acid—were also measured. Statistical analysis was by repeated-measures, 2-factor ANOVA or Kruskal–Wallis and Mann–Whitney U test; P < 0.05 was considered statistically significant.
Body weight was significantly decreased in all treatment groups after 5FU injection, with no change in body weight observed in any prebiotic treatment group. Total food intake was lower by ≥7% in the GOS treatment group pre-5FU than in all other groups (P < 0.05). Ileal villus height was 18% higher in GOS-treated rats pre-5FU than in respective water controls (P < 0.05). Jejunal and ileal villus height and crypt depth were significantly decreased in all treatment groups after 5FU injection, with no prebiotic effect observed. SCFAs were differentially increased in prebiotic treatment groups compared with water-only controls (P < 0.05).
FOS, GOS, and MOS have differential effects in modifying small intestinal pathology and SCFA profiles in rats with healthy and damaged small intestinal mucosa.
The microbiota of the gastrointestinal tract is a complex community of many different species of microorganisms, dominated by bacteria. This diverse population provides the host with an extensive ...array of enzymes and substrates which, together with the host's metabolic capabilities, provides an extensive metabolome available for nutrient and energy collection. We investigated broiler chickens to determine whether the abundance of certain members of the microbiota was correlated with the relative ability to extract energy from a typical wheat soybean diet. A number of mostly uncultured phylotypes were identified that significantly differed in abundance between birds with high apparent metabolizable energy (AME), measured as the difference between energy consumed and energy excreted, and those with low AME. Among the phylotypes that were more prevalent in birds with high energy efficiency, most were closely associated with isolates of bacterial groups that are commonly recognized as producing enzymes that degrade cellulose and/or resistant starch. Phylotypes that were negatively correlated with performance were all unknown and uncultured, a significant number belonging to an unknown class of Firmicutes. The identification of bacterial phylotypes correlated with the efficiency of energy use opens up the possibility of harnessing these bacteria for the manipulation of the host's ability to utilize energy. Increasing the ability to convert food to body weight is of interest to the agricultural industries, while the opposite is applicable in weight management and obesity control in humans.
Mucositis, characterized by ulcerative lesions along the alimentary tract, is a common consequence of many chemotherapy regimens. Chemotherapy negatively disrupts the intestinal microbiota, resulting ...in increased numbers of potentially pathogenic bacteria, such as Clostridia and Enterobacteriaceae, and decreased numbers of "beneficial" bacteria, such as Lactobacilli and Bifidobacteria. Agents capable of restoring homeostasis in the bowel microbiota could, therefore, be applicable to mucositis. Prebiotics are indigestible compounds, commonly oligosaccharides, that seek to reverse chemotherapy-induced intestinal dysbiosis through selective colonization of the intestinal microbiota by probiotic bacteria. In addition, evidence is emerging that certain prebiotics contribute to nutrient digestibility and absorption, modulate intestinal barrier function through effects on mucin expression, and also modify mucosal immune responses, possibly via inflammasome-mediated processes. This review examines the known mechanisms of prebiotic action, and explores their potential for reducing the severity of chemotherapy-induced mucositis in the intestine.
Although chemotherapy remains the current best practice for the treatment of neoplasia, the severity of its associated side-effects continues to impact detrimentally on the quality of life. Mucositis ...can affect both the oral cavity and intestine, and represents one of the most common side-effects of chemotherapy. It is characterized by ulceration, inflammation, diarrhoea, and intense abdominal pain. Despite extensive research there remains no definitive therapy for mucositis. This may be due to the multiple factors which contribute to its pathogenesis, including up-regulation of pro-inflammatory cytokines, increased apoptosis of epithelial cells, alteration of the gastrointestinal microbiota, and damage to the epithelium. Although employed increasingly in other gastrointestinal disorders, probiotics are yet to be comprehensively investigated in the treatment or prevention of chemotherapy-induced mucositis. Probiotic-based therapies have been shown to exert beneficial effects, including modulation of the microbiota and inhibition of pro-inflammatory cytokines. This review outlines the current evidence supporting the use of probiotics in intestinal mucositis, and suggests further research directions for the future.
The health benefits of the (n-3) PUFA, EPA, and DHA have created a demand for fish and fish oil, the main sources of these PUFA. Production animals, such as poultry, are potential alternate and ...sustainable sources of EPA and DHA, provided these fatty acids can be synthesized from plant-derived α-linolenic acid ALA, 18:3(n-3). Because elongases are potential control points in the conversion of ALA to DHA in rats, we examined the chicken elongases, ELOVL2 and ELOVL5, which had not been characterized. ELOVL2 activity was limited to C20–22 PUFA substrates and the major product of ELOVL2 metabolism of EPA was 24:5(n-3). This indicates that ELOVL2 can sequentially elongate EPA to docosapentaenoic acid DPA, 22:5(n-3) and then onto 24:5(n-3). ELOVL5 selectivity was broader with elongation of C18–22 PUFA substrates. The ability of chicken ELOVL5 to efficiently synthesize 24:5(n-3) is unique compared with ELOVL5 enzymes from other species. The expression of ELOVL5 was higher than ELOVL2 in livers of broiler chickens and their expression did not change when dietary ALA was increased from 0.6 to 1.3% of dietary energy for 42 d. The expression of both genes was higher than previously seen in rats. The chicken elongase enzymes are unlike those of any species studied to date, because both ELOVL2 and ELOVL5 have the ability to efficiently elongate DPA. In addition, the relative abundance of ELOVL2 and ELOVL5 in the liver suggests that chickens may be able to metabolize more DPA through to 24:5(n-3), the precursor of DHA, compared with other species such as rats.
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