Layer chicken microbiota:a comprehensive analysis of spatial and temporal dynamics across all major gut sections

Background The gut microbiota influences chicken health,welfare,and productivity.A diverse and balanced microbiota has been associated with improved growth,efficient feed utilisation,a well-developed immune system,disease resistance,and stress tolerance in chickens.Previous studies on chicken gut microbiota have predominantly focused on broiler chickens and have usually been limited to one or two sections of the digestive system,under con-trolled research environments,and often sampled at a single time point.To extend these studies,this investigation examined the microbiota of commercially raised layer chickens across all major gut sections of the digestive system and with regular sampling from rearing to the end of production at 80 weeks.The aim was to build a detailed picture of microbiota development across the entire digestive system of layer chickens and study spatial and temporal dynamics.Results The taxonomic composition of gut microbiota differed significantly between birds in the rearing and pro-duction stages,indicating a shift after laying onset.Similar microbiota compositions were observed between proven-triculus and gizzard,as well as between jejunum and ileum,likely due to their anatomical proximity.Lactobacil-lus dominated the upper gut in pullets and the lower gut in older birds.The oesophagus had a high proportion of Proteobacteria,including opportunistic pathogens such as Gallibacterium.Relative abundance of Gallibacterium increased after peak production in multiple gut sections.Aeriscardovia was enriched in the late-lay phase compared to younger birds in multiple gut sections.Age influenced microbial richness and diversity in different organs.The upper gut showed decreased diversity over time,possibly influenced by dietary changes,while the lower gut,specifi-cally cecum and colon,displayed increased richness as birds matured.However,age-related changes were inconsist-ent across all organs,suggesting the influence of organ-specific factors in microbiota maturation.Conclusion Addressing a gap in previous research,this study explored the microbiota across all major gut sections and tracked their dynamics from rearing to the end of the production cycle in commercially raised layer chickens.This study provides a comprehensive understanding of microbiota structure and development which help to develop targeted strategies to optimise gut health and overall productivity in poultry production.

Negative consequences of reduced protein diets supplemented with synthetic amino acids for performance,intestinal barrier function,and caecal microbiota composition of broiler chickens

The consequences of feeding broiler chickens with reduced protein(RP)diets for gut health and barrier function are not well understood.This study was performed to elucidate the effect of reducing dietary protein and source of protein on gut health and performance parameters.Four experimental diets included 2 control diets with standard protein levels either containing meat and bone meal(CMBM)or an all-vegetable diet(CVEG),a medium RP diet(17.5%in growers and 16.5%in finisher),and a severe RP diet(15.6%in grower and 14.6%in finisher).Off-sex Ross 308 birds were assigned to each of the 4 diets and performance measurements were taken from d 7 to 42 post-hatch.Each diet was replicated 8 times(10 birds per replicate).A challenge study was conducted on additional 96 broilers(24 birds per diet)from d 13 to 21.Half of the birds in each dietary treatment were challenged by dexamethasone(DEX)to induce a leaky gut.Feeding birds with RP diets decreased weight gain(P<0.0001)and increased feed conversion ratio(P<0.0001)from d 7 to 42 compared with control diets.There was no difference be-tween CVEG and CMBM control diets for any parameter.The diet containing 15.6%protein increased(P<0.05)intestinal permeability independent of the DEX challenge.Gene expression of claudin-3 was downregulated(P<0.05)in birds fed 15.6%protein.There was a significant interaction between diet and DEX(P<0.05)and both RP diets(17.5%and 15.6%)downregulated claudin-2 expression in DEX-challenged birds.The overall composition of the caecal microbiota was affected in birds fed 15.6%pro-tein having a significantly lower richness of microbiota in both sham and DEX-injected birds.Proteo-bacteria was the main phylum driving the differences in birds fed 15.6%protein.At the family level,Bifidobacteriaceae,Unclassified Bifidobacteriales,Enterococcaceae,Enterobacteriaceae,and Lachnospir-aceae were the main taxa in birds fed 15.6%protein.Despite supplementation of synthetic amino acids,severe reduction of dietary protein compromised performance and intestinal health parameters in broilers,evidenced by differential mRNA expression of tight junction proteins,higher permeability,and changes in caecal microbiota composition.

The temporal fluctuations and development of faecal microbiota in commercial layer flocks

The microbiota of the gastrointestinal tract influences gut health,which in turn strongly impacts the general health and productivity of laying hens.It is essential to characterise the composition and temporal development of the gut microbiota in healthy layers raised under different management systems,to understand the variations in typical healthy microbiota structure,so that deviations from this might be recognised and correlated with production and health issues when they arise.The present investigation aimed to study the temporal development and phylogenetic composition of the gut microbiota of four commercially raised layer flocks from hatch to end of the production cycle.Non-intrusive faecal sampling was undertaken as a proxy to represent the gut microbiota.Sequencing of 16S rRNA gene amplicons was used to characterise the microbiota.Beta diversity analysis indicated that each faecal microbiota was different across the four flocks and had subtly different temporal development patterns.Despite these inter-flock differences,common patterns of microbiota development were identified.Firmicutes and Proteobacteria were dominant at an early age in all flocks.The microbiota developed gradually during the rearing phase;richness and diversity increased after 42 d of age and then underwent significant changes in composition after the shift to the production farms,with Bacteroidota becoming more dominant in older birds.By developing a more profound knowledge of normal microbiota development in layers,opportunities to harness the microbiota to aid in the management of layer gut health and productivity may be more clearly seen and realised.

In vitro growth of gut microbiota with selenium nanoparticles

The application of nanoparticles rose steeply in the last decade,where they have become a common ingredient used in processed human food,improving food properties such as shelf life and appearance.Nanoparticles have also attracted considerable interest to the livestock industry,due to their efficacy in intestinal pathogen control,with the regulatory and consumer driven push for the removal of antibiotic growth promoters.The influence of selenium(Se) nanoparticles was investigated on a diverse and mature broiler caecal microbiota using in vitro culturing and 16 S rRNA gene sequencing methods for microbiota characterisation.Caecal microbiota was collected from 4 traditionally grown heritage roosters and grown for 48 h,in the presence and absence of Se nanoparticles,with 2 technical replicates each.The effect of rooster as a biological variable strongly overpowered the effects of nano-Se in the media,resulting in moderate effects on the structure and diversity of the caecal microbial community.However the nanoparticles showed a significant reduction(P <0.05) in the abundance of an emerging poultry pathogen,Enterococcus cecorum identical operational taxonomic units(OTU),which could be of notable interest in poultry production for targeted E.cecorum control without significant disturbance to the total microbial community.

Ultrastructure of the gastro intestinal tract of healthy Japanese quail(Coturnix japonica) using light and scanning electron microscopy

The Japanese quail(Coturnix japonica) are popular both as an alternative protein source and as a model of choice for scientific research in several disciplines. There is limited published information on the histological features of the intestinal tract of Japanese quail. The only comprehensive reference is a book published in 1969. This study aims to fill that niche by providing a reference of general histological features of the Japanese quail, covering all the main sections of the intestinal tract. Both light and scanning electron microscope(SEM) images are presented. Results showed that the Japanese quail intestinal tract is very similar to that of the chicken with the exception of the luminal koilin membrane of the gizzard. Scanning electron microscopic photomicrographs show that in the Japanese quail koilin vertical rods are tightly packed together in a uniform manner making a carpet-like appearance. This differs in chicken where the conformations of vertical rods are arranged in clusters.

Necrotic enteritis and antibiotic-free production of broiler chickens:Challenges in testing and using alternative products

The global trend towards raising broiler chickens without the use of in-feed antibiotics(IFAs)means that there is an ongoing need to develop alternative treatments capable of delivering the benefits that IFAs previously provided.IFAs supported the productivity performance of chickens and played a key role in maintaining their health.Necrotic enteritis(NE)is an important disease of broilers that affects health,productivity,and welfare,and was previously well controlled by IFAs.However,with the reduction in IFA use,NE is resurgent in some countries.Vaccines and various feed additives,including pre-,pro-,and postbiotics,phytobiotics,fatty acids,and phage therapies have been introduced as alternative methods of NE control.While some of these feed additives have specific activity against the NE pathogen,Clostridium perfringens,most have the more general goal of reinforcing gut health.Extensive reviews of the effects of many of these feed additives on gut health have been published recently.Hence,rather than cover previously well reviewed areas of research this review focuses on the challenges and pitfalls in undertaking experimental assessment of alternative NE treatments and translating laboratory research to real world commercial production settings.The review is based on the author's particular experience,reading,thoughts,and analysis of the available information and inevitably presents a particular understanding that is likely to be at odds with others thinking on these issues.It is put forward to stimulate thinking and discussion on the issues covered.