Fecal Particles Research Articles

Effect of feed ingredients on nutrient digestibility, waste production and physical characteristics of rainbow trout (Oncorhynchus mykiss) faeces.

This study assessed the effect of different dietary ingredients on the quantity and characteristics of faecal waste produced by rainbow trout (Oncorhynchus mykiss). Seven ingredients were tested: fish meal (FM), mussel meal (MM), poultry meal wet rendered (PM-W) or dry rendered (PM-D), insect meal (IM), single cell protein (SCP) and brewers grain protein (BGP). Eight experimental diets were formulated: a control diet (CON) being predominantly plant-based and seven test diets, which contained 70% of the CON diet and 30% of one of the test ingredients. Rainbow trout juveniles (65 g, 30 fish/tank) were fed the experimental diets at satiation for six weeks in triplicate groups. Dry matter (DM) and nutrient digestibility of diets and the test ingredients were measured. To estimate the faecal characteristics, particle size distribution (PSD) and removal efficiency of the faecal waste was determined. Nutrient digestibility of diets and ingredients differed significantly. Growth did not differ between the experimental diets, but DM digestibility was affected by the diet. Diets affected the amount of faecal waste produced, its removal efficiency (%) and the amount of non-removed faeces (g DM/kg DM feed). The highest and lowest removal efficiency was observed at FM and BGP diets, respectively. Accordingly, FM diet resulted in the lowest (37 g DM/kg DM feed), while BGP diet resulted in the highest (125 g DM/kg DM feed) amount of non-removed faeces. Additionally, it was also observed that differences in faecal removal efficiency can compensate for the variation in the quantity of faecal waste produced. Consistent with the faecal removal efficiency data, faeces PSD was also influenced by diets. FM and MM diets resulted in faeces with the lowest proportion of particles of <40 μm size, while BGP diet had the largest proportion of faecal particles of this size range. Furthermore, the effect of dietary ingredient composition was evident in the stability of faeces, with FM producing the most stable, whereas CON, BGP and SCP diets resulting in relatively unstable faecal pellets. In addition, due to differences in inclusion level of nutrients and their corresponding digestibility, the chemical composition of faeces differed between the diets. Overall, the study showed that dietary ingredient composition influences nutrient digestibility and is an important factor determining the amount of faecal waste produced, its removal efficiency, PSD, stability and composition in rainbow trout.

Persistence of E. coli in Streambed Sediment Contaminated with Faeces from Dairy Cows, Geese, and Deer: Legacy Risks to Environment and Health.

Legacy stores of faecal pollution in streambed sediments can result in delayed impacts on environmental quality and human health if resuspended into the overlying water column. Different catchment sources of faecal pollution can contribute to a legacy store of microbial pollutants, with size of stores influenced by microbial die-off and faecal accrual rates in the streambed. The aim of this study was to use a mesocosm experiment to characterise the persistence of E. coli derived from faeces of dairy cows, deer, and geese once introduced to streambed sediment under different temperature regimes. The settling rate of solid constituents of faecal material into streambed sediment once delivered into an aquatic environment was also quantified. The persistence patterns of E. coli in streambed sediment were found to vary as a function of faecal source and temperature; die-off of E. coli in sediment contaminated with goose faeces was more rapid than in sediments contaminated with dairy cow or deer faeces. Goose faeces also recorded a more rapid settling rate of faecal particles through the water column relative to dairy cow and deer faeces, suggesting a more efficient delivery of E. coli to streambed sediments associated with this faecal source. Our findings provide new evidence to improve understanding of the potential longer-term risks to both the environment and public health posed by sediments when contaminated with livestock, wildlife, and wildfowl faeces.

Study on Lowering the Group 1 Protease Allergens from House Dust Mites by Exposing to Todomatsu Oil Atmosphere

Group 1 protease allergens that persist in fecal particles from house dust mites (HDM) are the prevalent indoor aeroallergens and the primary triggers of dust mite allergy. Consequently, it is vital to discover a secure, efficient, affordable, and eco-friendly inhibitor to restrain these allergens. Herein, an assessment on the suppression of allergens Der f 1 and Der p 1 (predominant Group 1 allergens) with todomatsu oil derived from the remnants of Abies sachalinensis was performed using enzyme-linked immunosorbent assay (ELISA), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and molecular docking analysis in silico. The results demonstrated that todomatsu oil effectively suppresses allergens Der f 1 and Der p 1 by lowering their allergen contents, and the decline rate rises with increasing todomatsu oil concentration. The formation of alkyl hydrophobic interactions, pi-sigma bonds, and hydrogen bonds have been observed between oil ingredients and allergens Der f 1 and Der p 1. Intriguingly, the majority of oil ingredients prefer to dock on hydrophobic amino acids. Additionally, oil ingredients docked to the cysteine protease site on Der f 1 or IgG epitope on Der p 1 were discovered. Notably, the binding affinity (BA) score and inhibition constant (Ki) revealed that bornyl acetate, the component with the maximum relative proportion in todomatsu oil, is included in the top five ingredients with the best inhibition effectiveness. As a result, todomatsu oil has been identified as an efficient inhibitor against Group 1 HDM allergens and a viable measure to improve indoor air quality.

Disturbed gut virome with potent interferonogenic property in systemic lupus erythematosus

Accumulating evidence suggests an essential role of disturbed gut microbiota in the etiopathogenesis of systemic lupus erythematosus (SLE), but it remains unclear as to gut virome. In this study, fecal virus-like particles (VLPs) isolated from 76 non-treated SLE patients and 75 healthy controls were subjected to gut virome profiling. The proportion of bacteriophages was significantly elevated in the SLE gut, and the altered viral taxa were correlated with clinical parameters. Gut virome and bacteriome were closely associated with each other in SLE patients. The combination of gut viral and bacterial markers displayed better performance in distinguishing SLE patients from healthy controls. Further, VLPs from non-treated SLE patients promoted interferon-α production in an epithelial cell line and human immune cells. Intriguingly, the interferon-stimulatory capacity diminished in VLPs from post-treated SLE patients. Our findings may shed novel insights into SLE pathogenesis. Further in-depth understanding of gut virome might help develop future biomarkers and therapeutics for SLE patients.

&lt;i&gt;Chimonanthus salicifolius&lt;/i&gt; S. Y. Hu Extract improve constipation symptoms and regulate intestinal microbiota in mice

Chimonanthus salicifolius S. Y. Hu (C. salicifolius) is a unique medicinal plant of Magnolia in China, it could inhibit pathogens and prevent flu, which has been extensively applied for drinking tea. The purpose of this study was to analyze the main components of ethyl acetate extract of C. salicifolius (EAECS) and explore the effect of extract on loperamide-induced constipation in mice. The mice with constipation induced by loperamide were given different concentrations of C. salicifolius extract once a day for 14 days. The constipation-related parameters, stool particles, the time of the first black stool defecation and gastrointestinal (GI) transit rate were determined. In addition, the change of abundance and diversity in intestinal microbiota were analyzed. The results indicated that the main components in EAECS were rutin, nicotiflorin, quercetin and kaempferol. After administration, EAECS treatment relieved loperamide-induced constipation in mice, as evidenced by reduced defecation time and significantly increased GI transit rate, fecal particles and water content. At genus level, the extract also remarkably reduced Ruminococcus and increased the abundance of Lactobacillus and Bifidobacterium in intestinal tract of mice (all p ＜ 0.05). These findings indicated that EAECS effectively improved loperamide-induced constipation in mice and could be considered as a candidate treatment for constipation.

A simple approach to monitor faecal particle size in the Asian elephant - A proof of concept study

A simple approach to monitor faecal particle size in the Asian elephant - A proof of concept study

Practical low-fishmeal diets for rainbow trout (Oncorhynchus mykiss) reared in RAS: Effects of protein meals on fish growth, nutrient digestibility, feed physical quality, and faecal particle size

To evaluate strategies for optimizing waste in recirculating aquaculture systems, 1020 rainbow trout (initial live weight 17.2 ± 7.50 g/fish) were distributed into 12 tanks after 21 d of acclimation and fed during 84 days with four practical diets (crude protein: 49% DM; crude fat 26% DM; gross energy: 23 MJ kg-1) containing different rates of fishmeal and alternative protein meals, i.e. Diet FM (307 g kg-1 fishmeal, 61.2 g kg-1 poultry by-product meal); diet PBM (183 g kg-1 fishmeal, 168 g kg-1 poultry by-product meal); diet FeM (198 g kg-1 fishmeal, 61.2 g kg-1 poultry by-product meal, 76.5 g kg-1 hydrolysed feather meal); diet FeM+RM (171 g kg-1 fishmeal, 61.2 g kg-1 poultry by-product meal, 76.5 g kg-1 hydrolysed feather meal, 60.4 g kg-1 rapeseed meal). High structural integrity of extruded pellets and low oil leakage were measured in all diets, while the lowest water turbidity at 15 min after feed administration was recorded for FeM diet (2.7 vs. 12.7 mg L-1; p < 0.05). Diets did not affect fish specific growth rate (2.16% d-1). The lowest apparent digestibility of protein was measured with diet FeM (79.6%) and the highest with diet PBM (86.0%) (p < 0.001); apparent digestibility of lipids was higher in fish fed diets FM and PBM than the other diets (84.4% and 85.5% vs. 66.4% vs. 71.1%; p < 0.001). Fish fed diet PBM showed a higher percentage of retained faeces at mesh sizes 0.5–0.8 mm (33% vs. 30%; p < 0.005) and 0.3–0.5 mm (64% vs. 59%; p < 0.001) compared with the other diets. The replacement of fishmeal with poultry by-product- meal had positive effects on nutrient digestibility and faecal particle size. The replacement with hydrolysed feathers and rapeseed meals impaired nutrient digestibility but had positive implications for water turbidity.

Lack of evidence of viability and infectivity of SARS-CoV-2 in the fecal specimens of COVID-19 patients.

SARS-CoV-2 can be shed in feces and can enter sewage systems. In order to implement effective control measures and identify new channels of transmission, it is essential to identify the presence of infectious virus particles in feces and sewage. In this study, we attempt to utilize Molecular techniques, cell cultures and animal models to find out the infectivity of SARS-CoV-2 in the feces of COVID-19 patients. Our findings exclude the presence of infectious virus particles, suggesting that fecal-oral transmission may not be the main mode of transmission. Larger-scale initiatives are nevertheless required, particularly considering the emergence of new viral strains.

Variations in fecal pH and fecal particle size due to changes in dietary starch: Their potential as an on-farm tool for assessing the risk of ruminal acidosis in dairy cattle

This study evaluated the variations in fecal pH and particle size due to changes in dietary starch, and the potential of these variations as a tool to detect the risk of subacute ruminal acidosis (SARA) in dairy cows. Nine ruminally cannulated, non-lactating, non-pregnant Holstein cows were used in two 6-week experimental periods. In each period, cows were first fed a forage diet for 1 wk., then transitioned over 1 wk. to a 65% concentrate ration, which they consumed for 4 wk. continuously. Measurements were conducted when cows consumed 17.3, 21.9 and 28.8% dietary starch. Fecal pH and particle size were measured at 0, 4, 8 and 12 h relative to feeding in days 7, 11, 21, 28, 35, and 42 of each period. Ruminal pH was measured every 15 min. Data were analyzed with SAS, the statistical model included concentrate level, time of sampling and period as fixed effects and cow was considered as random effect. Data showed an interaction between dietary starch level and time relative to feeding on fecal pH, with a shift in its pattern due to diet change. Specifically, during low starch feeding (17.3%), fecal pH was highest before feeding and decreased thereafter, reaching lowest value 12 h post-feeding (P < 0.05). With the 21.9% starch diet, fecal pH did not change significantly after feeding. However, during high starch feeding (28.8%), fecal pH decreased, being lowest before feeding and increased (P < 0.05) during the day reaching highest values at 8 and 12 h post-feeding. Fecal pH was lower (P < 0.01) during the days of high starch feeding; though, it was maintained relatively stable through this timeframe. Increasing dietary starch decreased the proportion of small fecal particles (0.5 to 1.18 mm), but increased the proportion of large (>1.18 mm) and soluble particles (<0.5 mm). There were significant correlations among ruminal pH, fecal pH and fecal particle size of feces collected before feeding. For example, fecal pH was correlated with minimum and daily mean ruminal pH; the proportion of fecal particles 0.5 to 1.18 mm correlated with minimum and daily mean ruminal pH (P < 0.01). Log-linear dependency analyses indicated a strong effect of starch intake on fecal pH so that for every kg increase in starch intake, there was a reduction in fecal pH by 0.38 units. In addition, regression analysis showed that the proportion of fecal particles between 0.5 and 1.18 mm showed strong dependency on the ratio dietary physically effective fiber to starch (P < 0.01). Ruminal pH also correlated with fecal particle size of frozen/thawed samples, but with lower strength than fresh samples. Overall, evaluating variations of fecal pH and particle size holds potential as a non-invasive on-farm tool for assessing rumen pH and SARA risk.

Gut dysfunction may be the source of pathological aggregation of alpha-synuclein in the central nervous system through Paraquat exposure in mice

BackgroundOne of the most common types of neurodegenerative diseases (NDDs) is Lewy body disease (LBD), which is characterized by excessive accumulation of α-synuclein (α-syn) in the neurons and affects around 6 million individuals globally. In recent years, due to the environmental factors that can affect the development of this condition, such as exposure to herbicides and pesticides, so it has become a younger disease. Currently, the vast majority of studies on the neurotoxic effects of paraquat (PQ) focus on the late mechanisms of neuronal-glial network regulation, and little is known about the early origins of this environmental factor leading to LBD. ObjectiveTo observe the effect of PQ exposure on intestinal function and to explore the key components of communicating the gut-brain axis by establishing a mouse model. Methods and resultsIn this study, C57BL/6J mice were treated by intraperitoneal injection of 15 mg/kg PQ to construct an LBD time-series model, and confirmed by neurobehavioral testing and pathological examination. After PQ exposure, on the one hand, we found that fecal particle counts and moisture content were abnormal. on the other hand, we found that the expression levels of colonic tight junction proteins decreased, the expression levels of inflammatory markers increased, and the diversity and abundance of gut microbiota altered. In addition, pathological aggregation of α-syn was consistent in the colon and midbrain, and the metabolism and utilization of short-chain fatty acids (SCFAs) were also markedly altered. This suggests that pathological α-syn and SCFAs form the gut may be key components of the communicating gut-brain axis. ConclusionIn this PQ-induced mouse model, gut microbiota disruption, intestinal epithelial barrier damage, and inflammatory responses may be the main causes of gut dysfunction, and pathological α-syn and SCFAs in the gut may be key components of the communicating gut-brain axis.

Effect of dietary protein source and ingredient grinding size on fish performance, faecal waste production and characteristics of yellowtail kingfish (Seriola lalandi) fed restrictively and to apparent satiation

Recently, yellowtail kingfish (Seriola lalandi) is being cultured in recirculating aquaculture systems (RAS). Yellowtail kingfish have a poor faecal integrity, which makes the removal of faeces by traditional RAS technology difficult. Reducing the faecal waste load in RAS can be achieved by reducing the amount of faeces produced (e.g., increasing digestibility) and/or increasing the removal of faeces. This study assessed the effect of partial fish meal replacement by plant ingredients and the effect of ingredient grinding size on the amount of faecal waste produced and faecal characteristics, like faecal removal efficiency and particle size distribution (PSD), in yellowtail kingfish. This was investigated during two 35-d experiments, where fish were fed restrictively (experiment R) or to apparent satiation (experiment S). For each experiment, individual batches of four experimental diets were produced according to a 2 × 2 factorial design (protein source × ingredient grinding size). The formulas used were identical for both experiments. FM100 diets contained only fish meal as protein source, whilst at FM30-P70 diets approximately 70% of the fish meal were replaced by plant protein ingredients. The effect of ingredient grinding size was tested by including 40% of either a fine or coarse grinding mixture. Tanks were stocked with 20 fish and 27 fish for experiment R and experiment S, respectively. For each tank, fish performance, faecal waste production, faecal removal efficiency and faecal PSD were measured. During both experiments, ingredient grinding size did not affect the faecal removal efficiency or PSD, whilst fish fed the fine FM30-P70 diets restrictively showed a lower faecal waste production. The inclusion of plant ingredients resulted in a lower absolute growth and higher FCR. Furthermore, fish fed the FM30-P70 diets showed a higher faecal waste production, a smaller PSD and a lower faecal removal efficiency. This ultimately resulted in a higher amount of non-removed faeces by 58.3% and 37.1% compared to FM100 diets for the experiment R and experiment S, respectively. In conclusion, the replacement of fish meal with plant ingredients in yellowtail kingfish diets is challenging due to the adverse effects on fish performance, faecal waste production and faecal characteristics. However, feeding yellowtail kingfish to apparent satiation partly reduced these adverse effects of plant ingredient inclusion in terms of faecal waste production and faecal characteristics. Reducing the ingredient grinding size of yellowtail kingfish diets tended to lower the faecal waste production, whilst not negatively affecting the fish performance or faecal characteristics.

Reduction in SARS-CoV-2 Virus Infectivity in Human and Hamster Feces.

Objective: There is extensive evidence that SARS-CoV-2 replicates in the gastrointestinal tract. However, the infectivity of virions in feces is poorly documented. Although the primary mode of transmission is airborne, the risk of transmission from contaminated feces remains to be assessed. Design: The persistence of SARS-CoV-2 (infectivity and RNA) in human and animal feces was evaluated by virus isolation on cell culture and RT-qPCR, respectively. The exposure of golden Syrian hamsters to experimentally contaminated feces through intranasal inoculation has also been tested to assess the fecal-oral transmission route. Results: For periods that are compatible with average intestinal transit, the SARS-CoV-2 genome was noticeably stable in human and animal feces, contrary to the virus infectivity that was reduced in a time- and temperature-dependent manner. In human stools, this reduction was variable depending on the donors. Viral RNA was excreted in the feces of infected hamsters, but exposure of naïve hamsters to feces of infected animals did not lead to any productive infection. Conversely, hamsters could be experimentally infected following exposure to spiked fresh feces. Conclusion: Infection following exposure to naturally contaminated feces has been suspected but has not been established so far. The present work demonstrates that SARS-CoV-2 rapidly lost infectivity in spiked or naturally infected feces. Although the possibility of persistent viral particles in human or animal feces cannot be fully ruled out, SARS-CoV-2 transmission after exposure to contaminated feces is unlikely.

Critical roles of sepsis-reshaped fecal virota in attenuating sepsis severity.

Because studies on all fecal organisms (bacteria, fungi, and viruses) in sepsis are rare and bacteriophages during sepsis might have adapted against gut bacteria with possible pathogenicity, cecal ligation and puncture (CLP; a sepsis mouse model) was evaluated. In fecal bacteriome, sepsis increased Bacteroides and Proteobacteria but decreased Firmicutes, while fecal virome demonstrated increased Podoviridae when compared with sham feces. There was no difference in the fungal microbiome (predominant Ascomycota in both sham and CLP mice) and the abundance of all organisms between sepsis and control groups. Interestingly, the transfers of feces from CLP mice worsened sepsis severity when compared with sham fecal transplantation, as evaluated by mortality, renal injury (serum creatinine and histology), liver damage (liver enzyme and histology), spleen apoptosis, serum cytokines, endotoxemia, and bacteremia. In contrast, the transfers of fecal viral particles from sepsis mice, but not from sham mice, attenuated inflammation in CLP sepsis possibly through the decrease in several fecal pathogenic bacteria (such as Proteobacteria, Gammaproteobacteria, and Prevotellaceae) as evaluated by fecal microbiome analysis. Perhaps the isolation of favorable bacteriophages in sepsis feces and increased abundance ex vivo before oral treatment in a high concentration are beneficial.

Transplantation of bacteriophages from ulcerative colitis patients shifts the gut bacteriome and exacerbates the severity of DSS colitis

BackgroundInflammatory bowel diseases (IBDs) including Crohn’s disease (CD) and ulcerative colitis (UC) are characterized by chronic and debilitating gut inflammation. Altered bacterial communities of the intestine are strongly associated with IBD initiation and progression. The gut virome, which is primarily composed of bacterial viruses (bacteriophages, phages), is thought to be an important factor regulating and shaping microbial communities in the gut. While alterations in the gut virome have been observed in IBD patients, the contribution of these viruses to alterations in the bacterial community and heightened inflammatory responses associated with IBD patients remains largely unknown.ResultsHere, we performed in vivo microbial cross-infection experiments to follow the effects of fecal virus-like particles (VLPs) isolated from UC patients and healthy controls on bacterial diversity and severity of experimental colitis in human microbiota-associated (HMA) mice. Shotgun metagenomics confirmed that several phages were transferred to HMA mice, resulting in treatment-specific alterations in the gut virome. VLPs from healthy and UC patients also shifted gut bacterial diversity of these mice, an effect that was amplified during experimental colitis. VLPs isolated from UC patients specifically altered the relative abundance of several bacterial taxa previously implicated in IBD progression. Additionally, UC VLP administration heightened colitis severity in HMA mice, as indicated by shortened colon length and increased pro-inflammatory cytokine production. Importantly, this effect was dependent on intact VLPs.ConclusionsOur findings build on recent literature indicating that phages are dynamic regulators of bacterial communities in the gut and implicate the intestinal virome in modulating intestinal inflammation and disease.EQTzi7uzN3oVQtNZuyDoLGVideo

PSI-10 Relationships Between Fecal Characteristics, Rumen pH, and Intake During an Acidosis Challenge

Abstract The objectives were to: 1) determine the relationship of fecal particle size with rumen pH, fecal pH, dry matter intake (DMI) and 2) determine the ability of fecal characteristics to predict rumen pH and DMI. Decreased ruminal pH during an acidotic bout may reduce fiber digestion and increase subsequent washed fecal particle size. Data were collected in a metabolism experiment using18 ruminally cannulated steers. The study was a completely randomized design evaluating the effect of a lactate adaption before an acidosis challenge. Ruminal pH, DMI, and fecal characteristics (fecal pH and washed fecal particle size) were measured for 4 d after the acidosis challenge. Fecal particle size was measured with 7 sieves with diameters ranging from 4,750 to 600 µm. Average rumen pH over 4 d was associated (r = 0.60; P &amp;lt; 0.01) with mean fecal particle size. However, rumen pH was not correlated with fecal pH (P &amp;gt; 0.1). Fecal pH was not correlated with mean fecal particle size (P &amp;gt; 0.1). Mean fecal particle size was correlated with days after the acidosis challenge (r = 0.36; P &amp;lt; 0.01). Multiple regressions were performed with the GLMSELECT procedure of SAS 9.4 using stepwise selection. Rumen pH was best predicted (r2 = 0.22) by fecal particle size between 1,700 and 1,400 µm, 1,180 and 850 µm, and less than 600 µm. Dry matter intake was best predicted (r2 = 0.17) by fecal particle size between 2,360 and 1,700 µm, 1,400 and 1,180 µm, and 850 and 600 µm. Overall, results indicated mean fecal particle size was correlated with rumen pH and days after the acidosis challenge. Additional data are needed for fecal characteristics to accurately predict ruminal pH and DMI.

Chemical composition and physical characteristics of faeces in horses with and without free faecal liquid \u2013 two case-control studies

BackgroundFree faecal liquid (FFL) is a condition in horses characterised by two-phase (one solid and one liquid) separation of faeces. Causes of the condition are unknown, but disturbed hindgut fermentation has been suggested as it may alter biochemical composition and appearance of faeces in equines. However, information on faecal composition in horses with FFL is scarce. Faecal chemical composition (dry matter, osmolality, ash, macro minerals, short-chain fatty acids (SCFA) and pH) and physical characteristics (free liquid, sand, water holding capacity and particle size distribution) were compared in horses with (case) and without (control) FFL in two sub-studies. In sub-study I, faeces from 50 case-control horse pairs in Sweden and Norway were sampled in three sampling periods (SP1-SP3). In sub-study II, faeces from 32 case-control horse pairs in Germany were sampled on one occasion.ResultsIn sub-study I, faecal concentration and proportion of lactic acid (of total short-chain fatty acids, SCFA) and water holding capacity was lower in case compared to control horses. Other variables (content of dry matter, ash, sodium, calcium, phosphorous, magnesium, sulphur, and concentrations of i-butyric, n-valeric and total SCFA, ammonia-N as proportion of total N, and pH) were similar in faeces from case and control horses. In sub-study II, all analysed variables were similar in faecal samples from case and control horses. Faecal particle size distribution was similar in case and control horses, but the proportion of larger particles (2 and 1 mm) were lower and proportion of smaller particles (< 1 mm) was higher in sub-study I compared to in sub-study II.ConclusionsTo the authors’ knowledge, this is the first study to investigate faecal chemical composition and physical characteristics in horses with FFL. Case and control horses had similar total SCFA, pH and osmolality, indicating that hindgut fermentation was similar. However, small differences in concentration and proportion (of total SCFA) of lactic acid and water holding capacity of faeces were shown and are of interest for further studies of horses with FFL.

Effect of Soy Protein Products and Gum Inclusion in Feed on Fecal Particle Size Profile of Rainbow Trout

Replacement of fishmeal (FM) with alternative plant proteins, especially soybean meal (SBM), can cause a diarrhea-like symptom in rainbow trout (RBT), characterized by very fine fecal particles. These fines do not settle out in raceway effluent for collection and can contribute to pollution of receiving waters. In this study, two experiments were conducted. Experiment 1 examined effects of nine protein sources (sardine meal, menhaden meal, soy protein concentrates (SPC) (three types), SBM (regular and high protein), corn protein concentrate (CPC), and poultry by-product meal (PBM)) on fecal particle size distribution. Results showed that all five soy-based diets produced feces in RBT having 75.7–89.3% fines and only about 1.0% large particles, while the remaining four diets yielded feces having a balanced particle size distribution. Oligosaccharides present naturally in soy products, thought to contribute fecal fines, were not correlated to fecal particle size classes. Instead, high crude fiber content in soy-based diets was found to be responsible for unbalanced fecal particle distribution in RBT. Experiment 2 examined if improvements in formulation could reduce the negative effect of soy-based ingredients. Eight practical diets (FM, SPC, SPC + 0.3% guar gum, PBM + CPC, PBM + CPC + 20 or 30% SPC, and PBM + CPC + 20 or 30% SPC + 0.3% guar gum) were formulated to contain 40% protein and 20% lipid. Results showed that diets containing mixtures of PBM, CPC, and 20% or 30% SPC plus guar gum produced trout feces with the highest percentage of large particles and lowest of fines, while the diet containing SPC alone (56%) plus guar gum resulted in trout feces having the highest content of mid-size particles. It was concluded that crude fiber in soy protein products (SBM and SPC) caused undesirable fecal particle profiles in RBT, and the addition of guar gum could significantly alleviate this negative effect.

Increasing food intake affects digesta retention, digestibility and gut fill but not chewing efficiency in domestic rabbits (Oryctolagus cuniculus).

In ruminants, the level of food intake affects net chewing efficiency and hence faecal particle size. For nonruminants, corresponding data are lacking. Here, we report the effect of an increased food intake of a mixed diet in four domestic rabbit does due to lactation, and assess changes in particle size (as determined by wet sieving analysis) along the rabbit digestive tract. During lactation, rabbits achieved a distinctively higher dry matter intake than at maintenance, with a concomitant reduction in mean retention times of solute and particle markers, an increase in dry matter gut fill, a reduction in apparent digestibility of dry matter, and an overall increase in digestible dry matter intake. By contrast, there was no change in faecal mean particle size (mean ± SD: 0.58 ± 0.02 vs. 0.56 ± 0.01 mm). A comparison of diet, stomach content and faecal mean particle size suggested that 98% of particle size reduction occurred due to ingestive mastication and 2% due to digestive processes. Very fine particles passing the finest sieve, putatively not only of dietary but mainly of microbial origin, were particularly concentrated in caecum contents, which corresponds to retention of microbes via a ‘wash‐back' colonic separation mechanism, to concentrate them in caecotrophs that are re‐ingested. This study gives rise to the hypothesis that chewing efficiency on a consistent diet is not impaired by intake level in nonruminant mammals.

Lack of evidence for infectious SARS-CoV-2 in feces and sewage.

The SARS-CoV-2 can be excreted in feces and can reach sewage systems. Determining the presence of infective viral particles in feces and sewage is necessary to take adequate control measures and to elucidate new routes of transmission. Here, we have developed a sample concentration methodology that allows us to maintain viral infectivity. Feces of COVID-19 patients and wastewater samples have been analyzed both by molecular methods and cell culture. Our results show no evidence of infective viral particles, suggesting that fecal–oral transmission is not a primary route. However, larger-scale efforts are needed, especially with the emergence of new viral variants.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10096-021-04304-4.

Lessons in Innate and Allergic Immunity From Dust Mite Feces and Tick Bites.

Allergic diseases represent a major cause of morbidity in modern industrialized and developing countries. The origins and development of allergic immune responses have proven difficult to unravel and remain an important scientific objective. House dust mites (HDM) and ticks represent two important causes of allergic disease. Investigations into HDM fecal particles and tick bites have revealed insights which have and will continue to shape our understanding of allergic immunity. In the present review, focus is given to the role of innate immunity in shaping the respective responses to HDM and ticks. The HDM fecal particle represents a rich milieu of molecules that can be recognized by pathogen-recognition receptors of the innate immune system. Factors in tick saliva and/or tissue damage resultant from tick feeding are thought to activate innate immune signaling that promotes allergic pathways. Recent evidence indicates that innate sensing involves not only the direct recognition of allergenic agents/organisms, but also indirect sensing of epithelial barrier disruption. Although fecal particles from HDM and bites from ticks represent two distinct causes of sensitization, both involve a complex array of molecules that contribute to an innate response. Identification of specific molecules will inform our understanding of the mechanisms that contribute to allergic immunity, however the key may lie in the combination of molecules delivered to specific sites in the body.