Fecal Volatiles Research Articles

Association of faecal volatiles and steroids with behavioural expression during oestrous cycle of sheep (Ovis aries).

This study was investigated to determine the faecal volatiles, steroid hormones and their correlation with behavioural signs during oestrous cycle in sheep (Ovis aries). This experiment was monitored from pro-oestrous to met-oestrous phases for correlation of endocrine dependence biochemical constituents in faeces and blood to detection of oestrous biomarkers. Medroxyprogesterone acetate sponges were used for 8 days to bring uniformity of oestrus in sheep. Faeces were collected during different phases of cycle and subjected to determination of fatty acids, minerals, oestrogens and progesterone analysis. Likewise, blood samples were also obtained for enzymatic and no-enzymatic antioxidants. The results revealed that faecal progesterone and oestrogen levels significantly increased during pro-oestrous and oestrous phase, respectively (p < .05). The blood plasma enzymatic levels showed significant demarcation during the oestrous phase than other periods (p < .05). There were also reported marked variations in volatile fatty acids across different phases of the oestrous cycle. Interestingly, methyl octanoate, methyl cis-10 pentadecenoate and methyl heptadecanoate volatiles were found to be specific to oestrus period. In addition, methyl hexanoate, methyl palmitoleate and methyl cis-9 oleate were identified in met-oestrus, indicating their possible role to be an oestrous biomarker. It is concluded that the pattern of volatile compounds and faecal steroids, in association with behavioural patterns, could be measured as a non-invasive method of heat detection in sheep.

Xylanase Impact beyond Performance: Effects on Gut Structure, Faecal Volatile Fatty Acid Content and Ammonia Emissions in Weaned Piglets Fed Diets Containing Fibrous Ingredients.

The addition of xylanase to piglet diets is known to improve performance and nutrient digestibility. The present study aimed to assess the impact of new xylanase on the growth performance, nutrient digestibility, and gut function of weaned piglets. A total of 144 pigs, weaned at 28 days (7.48 kg initial body weight, IBW), were assigned to 36 pens and 9 pens per treatment. Dietary treatments were a basal complex control diet, and the basal diet supplemented with 45,000, 90,000 and 135,000 U/kg xylanase. Performance was measured at days 0, 14 and 35. At day 35, samples were collected for assessment of intestinal histology, and volatile fatty acid and ammonia concentrations. After two weeks post-weaning, additional 12 piglets (11.34 kg IBW) were placed in metabolic crates for assessment of apparent total tract nutrient digestibility using a dietary marker. The addition of xylanase at 90,000 and 135,000 U/kg significantly improved average daily gain (333.6 g/day control, 364.86 g/day, 90,000 U/kg, 405.89 g/day, 135,000 U/kg, p < 0.05), G:F (0.557 control, 0.612 90,000 U/kg, 0.692 135,000 U/kg, p < 0.05), and reduced diarrhoea. This was driven improved nutrient digestibility and villus height in the jejunum (372.87 µm control, 432.53 µm 45,000 U/kg, 465.80 µm 90,000 U/kg, 491.28 µm 135,000 U/kg, p < 0.05). Xylanase supplementation also linearly increased faecal butyrate levels and had a quadratic relationship with propionate concentrations. 135,000 U/kg xylanase also reduced ammonia emissions. In conclusion, dietary supplementation with xylanase improved growth performance and feed efficiency in weaning piglets, likely driven by improvements to gut structure and function.

Analysis of volatiles from feces of released Przewalski\u2019s horse (Equus przewalskii) in Gasterophilus pecorum (Diptera: Gasterophilidae) spawning habitat

The absolute dominant species that infests wild population of Przewalski’s horse (Equus przewalskii) is Gasterophilus pecorum, and feces of released Przewalski’s horse, a habitat odor, plays an important role in mating and ovipositing locations of G. pecorum. To screen out unique volatiles for attracting G. pecorum, volatiles from fresh feces of released horses at stages of pre-oviposition (PREO), oviposition (OVIP), and post-oviposition (POSO) of G. pecorum, and feces with three different freshness states (i.e., Fresh, Semi-fresh, and Dry) at OVIP were collected by dynamic headspace adsorption and determined by automatic thermal desorption GC–MS. Results show that there were significant differences in fecal volatiles within both test conditions. Of the five most abundant volatiles from the five individual samples, the most important volatile was ammonium acetate at OVIP/Fresh, followed by acetophenone (Semi-fresh), toluene (PREO, OVIP and POSO), butanoic acid (OVIP and Semi-fresh), acetic acid (PREO, POSO and Semi-fresh), 1,6-octadiene,3,7-dimethyl-,(S)- (PREO, OVIP and POSO), 1,5,9-undecatriene,2,6,10-trimethyl-,(Z)- (PREO and Semi-fresh) and caprolactam (all conditions), which seem to be critical substances in oviposition process of G. pecorum. The findings may be beneficial to development of G. pecorum attractants, facilitating prevention and control of infection by G. pecorum to released Przewalski’s horse.

Orientation of Belminus triatomines to cockroaches and cockroaches’ fecal volatiles: an ethological approach

Most triatomine bugs (Hemiptera: Reduviidae: Triatominae) are hematophagous, though Belminus species can live off of cockroach hemolymph to complete their life cycle. In this work, we described the fixed action pattern (FAP) employed by B. ferroae to identify, approach, and suck on a living cockroach. The FAP described here is composed of the following stereotyped behaviors: (1) visual and/or olfactory detection of the cockroach, (2) reaching, (3) cautious approach, (4) antennal exploration, (5) extension of the proboscis, (6) piercing to sedate, (7) walking away and waiting (postsedation behavior), (8) second cautious approach, (9) extension of the proboscis, (10) piercing to suck hemolymph. The FAP sequence observed suggests that Belminus bugs are not predators like the rest of reduviids (assassin bugs)—but are kleptophagous ectoparasites, since they do not attack and kill a prey but rather steal hemolymph from its invertebrate host. Based on these ethological observations, we propose kleptophagy as a trait that naturally groups the Belminus species into the Triatominae subfamily. In order to identify chemicals cues that could elicit such FAP, we examined the behavior of B. corredori, B. ferroae, and B. herreri in response to the cockroaches’ odor, fresh cockroach feces and fresh rodent wastes. The last two sources were tested based on the assumption that abundant chemicals near host refuges could serve as cues for host orientation. We found that the cockroach odor emanating from a box significantly attracted B. corredori and B. herreri in a still air olfactometer. The three Belminus species approached the captive cockroach after 1 h, but avoided to climb the box. Odors emanating from the cockroach feces attracted B. corredori and B. ferroae in a Y-olfactometer. Triatomines and their hosts have intimately shared the same refuge for millions of years; certain molecules occur across invertebrate and vertebrate refuges and are recurrent in human abodes, thus plausibly explaining how these bugs can readily switch to the domestic habitat, while keeping with their kleptophagous nature.

Inter-kingdom relationships in Crohn’s disease explored using a multi-omics approach

ABSTRACT The etiology of Crohn’s disease (CD) is multifactorial. Bacterial and fungal microbiota are involved in the onset and/or progression of the disease. A bacterial dysbiosis in CD patients is accepted; however, less is known about the mycobiome and the relationships between the two communities. We investigated the interkingdom relationships, their metabolic consequences, and the changes in the fungal community during relapse and remission in CD. Two cohorts were evaluated: a British cohort (n = 63) comprising CD and ulcerative colitis patients, and controls. The fungal and bacterial communities of biopsy and fecal samples were analyzed, with the fecal volatiles; datasets were also integrated; and a Dutch cohort (n = 41) comprising CD patients and healthy controls was analyzed for stability of the gut mycobiome. A dysbiosis of the bacterial community was observed in biopsies and stool. Results suggest Bacteroides is likely key in CD and may modulate Candida colonization. A dysbiosis of the fungal community was observed only in the Dutch cohort; Malassezia and Candida were increased in patients taking immunosuppressants. Longitudinal analysis showed an increase in Cyberlindnera in relapse. Saccharomyces was dominant in all fecal samples, but not in biopsies, some of which did not yield fungal reads; amino acid degradation was the main metabolic change associated with CD and both bacteria and fungi might be implicated. We have shown that Bacteroides and yeasts may play a role in CD; understanding their role and relationship in the disease would shed new light on the development and treatment of CD.

Volatile metabolomic signatures of rabies immunization in two mesocarnivore species.

Rabies is a zoonotic disease caused by infection with rabies virus, which circulates naturally in several wild carnivore and bat reservoirs in the United States (US). The most important reservoir in the US from an animal and public health perspective is the raccoon (Procyon lotor). To prevent the westward expansion of a significant raccoon rabies epizootic along the eastern seaboard, an operational control program implementing oral rabies vaccination (ORV) has existed in the US since the 1990s. Recently, two vaccine efficacy studies conducted with raccoons and striped skunks (Mephitis mephitis) provided the opportunity to determine if volatile fecal metabolites might be used to non-invasively monitor ORV programs and/or predict virus protection for these species. The volatile metabolome is a rich source of information that may significantly contribute to our understanding of disease and infection. Fecal samples were collected at multiple time points from raccoons and striped skunks subjected to oral treatment with rabies vaccine (or sham). Intramuscular challenge with a lethal dose of rabies virus was used to determine protection status at six (raccoons) and 11 (skunks) months post-vaccination. In addition to fecal samples, blood was collected at various time points to permit quantitative assessment of rabies antibody responses arising from immunization. Feces were analyzed by headspace gas chromatography with mass spectrometric detection and the chromatographic responses were grouped according to cluster analysis. Cluster scores were subjected to multivariate analyses of variance (MANOVA) to determine if fecal volatiles may hold a signal of immunization status. Multiple regression was then used to build models of the measured immune responses based on the metabolomic data. MANOVA results identified one cluster associated with protective status of skunks and one cluster associated with protective status of raccoons. Regression models demonstrated considerably greater success in predicting rabies antibody responses in both species. This is the first study to link volatile compounds with measures of adaptive immunity and provides further evidence that the volatile metabolome holds great promise for contributing to our understanding of disease and infections. The volatile metabolome may be an important resource for monitoring rabies immunization in raccoons and striped skunks.

Sa1935 – Comparing Faecal Volatile Organic Compounds Following Administration of Two Different Probiotic Supplements

Sa1935 – Comparing Faecal Volatile Organic Compounds Following Administration of Two Different Probiotic Supplements

Two Sex-Specific Volatile Compounds Have Sex-Specific Repulsion Effects on Adult Locusts Locusta migratoria manilensis (Meyen) (Orthoptera: Acrididae)

Gregarious locusts use volatile semiochemicals released from their bodies and feces to regulate their biological characteristics, and many of these compounds are sex-specific. The locust Locusta migratoria manilensis (Meyen) (Orthoptera: Acrididae) is a frequent plague species in China, but very little is known of its olfactory behavioral ecology. In our previous study, one malespecific compound (2-heptanone) was identified from body volatiles of gregarious adult L. m. manilensis. In the present study, six compounds were identified from fecal volatiles of gregarious adult L. m. manilensis using a gas chromatograph coupled to a mass spectrometer: 3-Methyl-1-butanol, cyclo hexanol, 2,5-dimethylpyrazine, 6-methyl-5-hepten-2-one and 2,6,6-trimethyl-2-cyclohexene-1,4-dione were present in the fecal volatiles of both sexes, and 2,2,6-trimethylcyclohexanone only in that of females. Olfactometric bioassays indicated that the male-specific 2-heptanone repelled the adult males, but had no effect on females. On the other hand, female-specific 2,2,6-trimethylcyclohexanone was found to repel the adult females, but had no effect on males. The two sex-specific compounds may help to improve reproductive efficiency of the locusts.

Behavioural and electrophysiological responses ofTriatoma dimidiata nymphs to conspecific faecal volatiles.

The behavioural and electrophysiological (electroantennography) responses of the first two instars of Triatoma dimidiata (Hemiptera: Reduviidae) Latreille to fresh and dry faecal headspace volatile extracts from fifth instar conspecific nymphs and synthetic compounds were analysed in this study. Recently emerged nymphs (3-5 days) aggregated around filter paper impregnated with dry faeces and around filter paper impregnated with extracts from both fresh and dry faeces. Older first instars (10-15 days) and second instars aggregated around filter paper impregnated with fresh and dry faeces, and their respective headspace extracts. Dry faecal volatile extracts elicited the strongest antennal responses, followed by fresh faecal extracts. Gas chromatography-mass spectrometry analysis of dried faecal headspace volatiles demonstrated the presence of 12 compounds: 2-ethyl-1-hexanol, 1,2,4-trimethylbenzene, n-octadecane, n-nonadecane, n-eicosane, n-heneicosane, n-tricosane, n-pentaeicosane, n-hexaeicosane, n-octaeicosane, nonanal, and 4-methyl quinazoline. In fresh faecal headspace extracts, only nonanal was clearly detected, although there were other trace compounds, including several unidentified sesquiterpenes. Four of the 11 compounds tested individually elicited aggregation behaviour at concentrations of 100 ng/µL and 1 µg/µL. A blend containing these four components also mediated the aggregation of nymphs. These volatiles may be valuable for developing monitoring methods and designing sensitive strategies to detect and measure T. dimidiata infestation.

Flatography: Detection of gastrointestinal diseases by faecal gas analysis.

Patients presenting with gastro-intestinal symptoms might suffer from a range of possible underlying diseases. An unmet need exists for novel cost-effective, reproducible, easy-to-perform and non-invasive tests. Hippocrates used body odours to diagnose diseases circa 460 before Christ. The art of diagnostic smelling is making a promising high-tech come-back with portable "electronic diagnostic noses". Analysis of faecal volatile organic compounds is a novel field in metabolomics with considerable potential to improve the diagnosis, phenotyping and monitoring of gastro-intestinal disease. Challenges will be to mature over the coming years by development of a standardized methodology for stool sample collection, storage, handling and analysis. Furthermore, key volatiles need to be identified to improve test accuracy and sensitivity by development of sensors tailored toward the accurate identification of disease specific volatiles. If these challenges are adequately faced, analysis of faecal volatiles has realistic potential to considerably improve screening, diagnosis and disease monitoring for gastro-intestinal diseases.

A correlation of fecal volatiles and steroid hormone profiles with behavioral expression during estrous cycle of goat, Capra hircus

Chemical signals (both volatile and non-volatile) form the major communication channels in animals. These signals are transferred mainly through excretory sources to facilitate inter-individual communication. In particular, the reproductive cycle of female mammals, including goats, exhibits significant changes in the constituents of their excretory products, and female mammals also express different behavioral patterns. We propose that feces is one of the important sources of chemo-signals in goats. However, the behavioral patterns and analysis of excretory sources based on chemical communication have not yet been studied in the Indian goat, Capra hircus. To validate our hypothesis, we analyzed the behavioral patterns and the volatiles and steroid hormone profiles in the feces samples of female goats during the estrous cycle. Here, we synchronized the estrous cycle in six female goats and obtained feces samples. The samples were extracted with dichloromethane and analyzed using gas chromatography–mass spectrometry. A portion of the sample was used for hormone assay to confirm the phases in the estrous cycle. Induction of she-goats into estrus was detected from the vaginal swelling, mucus discharge, restlessness, reduced milk secretion, bellowing, bleating, frequent urination, standing heat, allowing the male to mount, mounting on other females and teasing of males. The repeated male behaviors viz., flehmen, mounting, penile protrusion, body rubbing, dominance over other males and finally coitus with estrus female by male goats were observed. Analysis of volatiles revealed a total of twenty-four compounds combining all the phases in the estrous cycle. Among those, some of the volatile compounds and two antioxidants (ascorbic acid and vitamin E) were estrus-specific. Based on the fecal steroid analysis, higher level of estradiol during estrus and higher level of progesterone during post-estrus were observed. The behavioral patterns of female and male goats combined with qualitative differences in the volatile compounds and the two antioxidants rendered the estrus identifiable. Furthermore, the fecal steroid analysis also supported the detection of hormonal status during the estrous cycle. To the best of our knowledge, this is the first report correlating the behavior with volatiles and hormones in the feces samples from female Indian goats. It is concluded that the volatile pattern and hormone profile in feces, supported by specific behavioral patterns, should be considered a better modality of non-invasive estrus detection in goats.

Optimisation of Sample Preparation for Direct SPME-GC-MS Analysis of Murine and Human Faecal Volatile Organic Compounds for Metabolomic Studies

The analysis of volatile organic compounds (VOCs) emitted from biological fluids such as blood, urine, breath and faeces, has been receiving more attention from researchers and clinicians due to their contribution to the metabolome and potential use as diagnostic tools in clinical settings. The faecal metabolome represents the final product of a complex interaction involving the gut microbiota and cell metabolism and an accurate measurement of the faecal volatile organic metabolome enables a better understanding of disease-related metabolic pathways and, eventually, identifying potential biomarkers. However, there is a lack of published evidence evaluating the sample preparation steps for faecal metabolome analysis and no well-defined protocol has been established. Consequently, different research groups employ diverse methodologies, which, ultimately, prevent comparison of results between laboratories. We evaluated different aspects of sample preparation when processing murine and human faecal samples through a pipeline involving solid phase micro-extraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS). We identified the sample volume, the SPME fibre coating, the extraction conditions and the vial volume that produce the most accurate and reproducible results. Finally, we propose an optimized method for the direct SPME-GC-MS analysis of VOCs in murine and human faecal samples. To the best of our knowledge, this is the first work evaluating different aspects of sample preparation for direct SPME-GC-MS analysis of VOCs and the first method proposed for the analysis of murine and human faecal samples. In addition, our proposed method can be coupled to the Automated Mass Spectral Deconvolution and Identification System (AMDIS) and the R software package, Metab, in order to produce results in a reliable and high-throughput manner.

The Use of SIFT-MS in Profiling the Faecal Volatile Metabolome in Horses with Colic: A Pilot Study

SIFT-MS is used for the first time in profiling the volatile organic profile in faecal headspace in two groups of horses admitted to an equine hospital, one group with acute intestinal disease (colic) affecting the large colon, plus a control group of similarly managed horses admitted for non-gastrointestinal/metabolic reasons (e.g. acute orthopaedic injury). Compounds in faecal headspace which show statistically significant concentration differences between the groups are acetone and methanol. In addition, some ions at various m/z values show significantly different ion counts between the groups. Further information may be gleaned by using multivariate statistics in evaluating the differences between the two horse groups. Principal components analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were evaluated for reducing the dimensionality of the SIFT-MS data, and OPLS-DA was found to be best at discriminating between the groups, particularly with SIFT-MS data acquired using the H3O+ precursor ion. Analysis of these data also show the significance of ammonia as a discriminating ion. These results show that SIFT-MS may potentially be used on the headspace of horse faecal samples for detecting altered microbial fermentation associated with acute intestinal disease of the colon. Keywords: SIFT-MS, metabolic profiling, horse volatile metabolome.

PWE-169 Analysis of faecal volatiles from young children infected with and without rotavirus

IntroductionRotavirus is the most common cause of severe diarrhoea among infants and young children. Rotavirus is usually an easily managed disease of childhood, but worldwide nearly 500 000 children under...

Electrophysiological response patterns of 16 olfactory neurons from the trichoid sensilla to odorant from fecal volatiles in the locust, locusta migratoria manilensis

Locusts are the most serious pests of crops in greater part of the world. They locate their host plants primarily through olfactory cues, using antennal chemosensilla, which house olfactory receptor neurons (ORNs). Despite the great economical interest of these species, their olfactory neurons have been poorly investigated at the functional level. In this study, we have used single sensillum recordings (SSRs) to obtain response patterns of ORNs from the antennal trichoid sensilla to various chemicals in the oriental locust Locusta migratoria. On the basis of their spontaneous spike amplitudes, trichoid sensilla could be distinguished into two types, housing two or three ORNs, respectively. These two structural types could be further classified into seven functional subtypes. Nine different odorants that are present in the locust feces were used as stimulants during SSRs. In particular, benzaldehyde elicited inhibitory responses in most of the ORNs tested. Moreover, in a majority of these ORNs, the excitatory responses obtained with trans-2-hexenal or 2-heptanone was inhibited when benzaldehyde was mixed with these stimulants. At least 16 response patterns of these ORNs to nine chemicals were identified by SSRs, suggesting a high complexity of the cellular mechanisms underlying chemoreception in locusts.

Fecal volatile components elicit aggregation in the oriental migratory locust, Locusta migratoria manilensis (Orthoptera: Acrididae)

Abstract The aggregation components from fecal volatiles of the oriental migratory locust, Locusta migratoria manilensis were identified with gas chromatographic/electroantennographic detector (GC-EAD), GC-MS (mass spectrometry) analyses and behavioral bioassays. Both last instar nymphs and adults of the oriental migratory locust have similar aggregation pheromones in their volatiles. A total of 11 electrophysiologically active compounds, namely, hexanal, cyclohexanol, heptanal, phenol, 2,5-dimethyl-pyrazine, benzyl alcohol, benzaldehyde, guaiacol, nonanal, 2,6,6-trimethyl-2-cyclohexene-1,4-dione and decyl aldehyde were identified in the fecal volatiles of 2-day-old immature adult male locusts. Only hexanal, nonanal, benzaldehyde, cyclohexanol and 2,5-dimethyl-pyrazine elicited significant aggregation responses in immature 2-day-old adult males. However, adult males had significantly lower behavioral responses to synthetics of five single compounds than the blend of cyclohexanol, 2,5-dimethyl-pyrazine, benzaldehyde, nonanal, hexanal in ratios of 100: 100: 2: 60: 30 in the range of 30–60 μg/mL. We propose that it is the blend of these five compounds that plays a key role in eliciting and sustaining aggregation in gregarious oriental migratory locusts. These results also showed that the aggregation pheromones of the oriental migratory locust are significantly different from those found in the desert locust.

OC-005 Does irritable bowel syndrome smell different from irritable bowel disease? A study of faecal volatile analysis in inflammatory bowel syndrome

Introduction Irritable bowel syndrome (IBS) is considered to be a functional disorder of gastrointestinal tract, the cause of which remains inadequately identified. Since there are no diagnostic markers, symptoms based criteria are currently used to confirm the diagnosis. Due to similar clinical presentation, it is yet a challenging task to distinguish it from inflammatory bowel disease (IBD) in both primary care and specialist settings. Volatile compounds are chemical which may be emitted from faeces and reflect the pathophysiological environment of the bowel. Understanding changes in their pattern could provide diagnostic information about various bowel disorders. Methods We aimed to analyse the faecal volatile pattern of patients with diarrhoea predominant IBS and compare it with IBD. We studied 90 individuals, 20 from diarrhoea predominant IBS, 50 from active IBD (CD=25, UC 25), and 20 from healthy individuals. Diagnosis of IBS was confirmed using symptoms based criteria (Manning, Rome III) while all individual with IBD had histological diagnosis. Fresh samples were aliquoted in 10 ml vials and faecal volatile were extracted using solid phase micro-extraction fibre injected into the head space and were analysed by gas chromatography/mass spectrometery. Volatile compounds were identified using NIST library and manual visualisation using fragmentation pattern. Results From 400 VOCs identified, 25 were selected using univariate analysis at 0.007 significant level. These were used in forward stepwise entry analysis to construct a predictive model which showed significant value in separating IBS from active IBD and healthy controls. On cross-validation, the IBS: IBD model remains significantly stable: 90% of patients were correctly diagnosed. This model has sensitivity of 95% and NPV 90%. Conclusion These interim results show that VOCs may be used to distinguish IBS from IBD and either from healthy controls. Further data will provide more information to identify this group more clearly from IBD and allow us to further validate this model.

Binding specificity of locust odorant binding protein and its key binding site for initial recognition of alcohols

Odorant binding proteins (OBPs) are required for olfaction perception, and thus may be possible targets for controlling the population of pests by interfering with their chemical communication. A single OBP LmigOBP1 has been identified in the antennae of Locusta migratoria, though four isoforms have been detected. Here, we have investigated the ligand-binding specificity of LmigOBP1 using 67 volatile odor compounds. Fluorescence assays indicate that LmigOBP1 does not bind fecal volatiles or green leaf odors, but shows high affinity for some linear aliphatic compounds, with pentadecanol and 2-pentadecanone being the strongest binding ligands. A 3-dimensional (3D) model of LmigOBP1 was built by homology modeling. Docking simulations based on this model suggested that Asn74 of LmigOBP1 is a key binding site, and this was validated by site-directed mutagenesis and fluorescence assays. We suggest that, as a general rule, a hydrophilic amino acid at the entrance of the binding cavity participates in initial recognition of ligands, and contributes to ligand-binding specificity of OBPs.

Disruption of aggregation behaviour of oriental migratory locusts (Locusta migratoria manilensis) infected with Nosema locustae

Abstract: The effect of Nosema locustae infection on the aggregation behaviour of the oriental migratory locust, Locusta migratoria manilensis, was studied using a two‐choice arena olfactometer and electroantennography (EAG). Infected locusts had low antennal sensitivity and aggregation responses to faecal extracts and to locust body volatiles. Infected fifth instar nymphs had significantly lower aggregation index than the uninfected nymphs, although with fourth instars the effect on aggregation behaviour only occurred in infected females. With regard to antennal receptor sensitivity, infected adult locusts had significantly lower EAG amplitudes in response to extracts from faeces of the adult males. The effect was most pronounced in female locusts. In contrast, there was no significant difference in the EAG responses between the fifth instar male and female nymphs. Further analysis revealed that EAG responses of fifth instar nymphs and adults infected with N. locustae to the faecal extract and volatiles from fifth instar solitary‐reared nymphs were not significantly affected. In contrast, infected nymphs and adults had remarkably low EAG amplitudes for the remaining stimuli.

The Impact of Supplemental Dietary Methionine Sources on Volatile Compound Concentrations in Broiler Excreta

The impact of different Met sources on broiler fecal odor volatiles was determined by evaluating the types of sulfur compounds produced in broiler excreta. Two experiments were conducted using straight-run broiler chicks randomly distributed in battery cages, with 3 replicate pens of 16 birds each. The treatment groups were 1) dry Met hydroxy analogue (dry MetHA), 2) sodium methioninate aqueous solution (NaMet), 3) liquid Met hydroxy analogue (Liq MetHA), 4) D,L- Met, and 5) no supplemental Met (control group). The Met activities of each Met source were 52, 45.9, 88, and 98%, respectively. All diets were formulated to contain either 0.8% (experiment 1) total Met activity or 0.5% Met activity in the starter and 0.38% Met activity in the grower (experiment 2) (except the control group, 0.35% Met activity), but otherwise met NRC nutrient requirements (NRC, 1994). Diets were fed ad libitum from d 1 to 6 wk of age. There were no significant differences in BW among the treatments. All excreta were collected in litter pans lined with aluminum foil. In experiment 1, at wk 6, broiler excreta were collected for a 24-h period, and 4.5 g of broiler excreta from each treatment group was collected into 15-mL headspace vials. Samples were analyzed by gas chromatography/mass spectrometry (GC/MS). The volatile sulfur compounds that were identified and quantified in the broiler excreta were H2 S, carbonyl sulfide (COS), methyl mercaptan (CH3 SH), dimethyl disulfide (CH3 SSCH3), and dimethyl trisulfide (CH3 SSSCH3). The NaMet treatment group had significantly higher concentrations of H2 S, COS, and CH3 SSCH3 compared with all other treatment groups. The Liq MetHA group had significantly lower concentrations of H2 S, COS, CH3 SH, and CH3 SSCH3 compared with the other treatment groups. The dry MetHA group significantly had the highest concentration of CH4 SH. The D,L-Met treatment group had the significantly highest concentration of CH3 SSSCH3 and the lowest concentration of H2 S. The control group had the significantly lowest concentrations of CH3 SH, CH3 SSCH3, and CH3 SSSCH3 compared with the other treatment groups. In experiment 2, at wk 6, an electronic nose was used to evaluate 15 air samples per treatment group. In addition, 15 air samples (containing 6 to 8 L of air in a Tedlar bag, 3 samples per treatment group) were collected for odor evaluation by a sensory panel. Electronic nose sensor data revealed that volatile compounds in broiler excreta from the control group were significantly different from the other 4 treatment groups. Evaluation of the air samples by a sensory panel determined that there was a statistically significant difference in odor threshold detection between the control group and the other treatment groups. The dilutions to threshold of control group, NaMet, dry MetHA, Liq MetHA, and D,L-Met were 350, 492, 568, 496, and 526 odor units, respectively. These findings demonstrate that dietary Met sources significantly influenced odorous volatile concentrations in broiler excreta.