RESUMEN
Infection with the foodborne pathogen Campylobacter is the leading bacterial cause of human foodborne illness in the United States. The objectives of this experiment were to test the hypothesis that mixed microbial populations from the bovine rumen may be better at excluding Campylobacter than populations from freshly voided feces and to explore potential reasons as to why the rumen may be a less favorable environment for Campylobacter than feces. In an initial experiment, C. jejuni cultures inoculated without or with freshly collected bovine rumen fluid, bovine feces or their combination were cultured micro-aerobically for 48 h. Results revealed that C. jejuni grew at similar growth rates during the first 6 h of incubation regardless of whether inoculated with the rumen or fecal contents, with rates ranging from 0.178 to 0.222 h-1. However, C. jejuni counts (log10 colony-forming units/mL) at the end of the 48 h incubation were lowest in cultures inoculated with rumen fluid (5.73 log10 CFUs/mL), intermediate in cultures inoculated with feces or both feces and rumen fluid (7.16 and 6.36 log10 CFUs/mL) and highest in pure culture controls that had not been inoculated with the rumen or fecal contents (8.32 log10 CFUs/mL). In follow-up experiments intended to examine the potential effects of hydrogen and hydrogen-consuming methanogens on C. jejuni, freshly collected bovine feces, suspended in anaerobic buffer, were incubated anaerobically under either a 100% carbon dioxide or 50:50 carbon dioxide/hydrogen gas mix. While C. jejuni viability decreased <1 log10 CFUs/mL during incubation of the fecal suspensions, this did not differ whether under low or high hydrogen accumulations or whether the suspensions were treated without or with the mechanistically distinct methanogen inhibitors, 5 mM nitrate, 0.05 mM 2-bromosulfonate or 0.001 mM monensin. These results suggest that little if any competition between C. jejuni and hydrogen-consuming methanogens exists in the bovine intestine based on fecal incubations.
RESUMEN
Lipolysis and biohydrogenation in ruminal animals promote the accumulation of saturated fatty acids in their meat and milk. Antibodies were generated against key ruminal lipase contributors Anaerovibrio lipolyticus, Butyrivibrio fibrisolvens, Propionibacterium avidum and acnes. An anti-Pseudomonas lipase antibody was generated to determine if an antibody against a purified protein would be more effective. Each bacterium was cultured and assayed without or with increasing levels of each antibody. Butyrivibrio fibrisolvens H17C also participates in biohydrogenation and therefore the antibody was tested to determine if it could effectively reduce biohydrogenation. Butyrivibrio fibrisolvens was assayed without and with the anti-B. fibrisolvens antibody and linoleic or α-linolenic acid. All antibodies were effective at reducing lipolysis with the anti-Pseudomonas lipase averaging a 78% reduction. The anti-B. fibrisolvens showed a tendency for a reduction (P=0.0713) in biohydrogenation products of α-linolenic acid. Results demonstrate that lipolysis and biohydrogenation can be immunologically inhibited in vitro.
Asunto(s)
Anticuerpos Antibacterianos/química , Ácidos Grasos/química , Lipólisis/fisiología , Propionibacterium/efectos de los fármacos , Butyrivibrio/efectos de los fármacos , Hidrogenación , Ácido Linoleico/química , Lipasa/metabolismo , Ácido alfa-Linolénico/químicaRESUMEN
Thymol is a natural product that exhibits antimicrobial activity in vitro but in vivo results indicate that absorption within the proximal alimentary tract precludes its delivery to the distal gut. Presently, the anti-Campylobacter activity of thymol was compared against that of thymol-ß-D-glucopyranoside, the latter being resistant to absorption. When treated with 1 mM thymol, Campylobacter coli and jejuni were reduced during pure or co-culture with a ß-glycoside-hydrolysing Parabacteroides distasonis. Thymol-ß-D-glucopyranoside treatment (1 mM) did not reduce C. coli and jejuni during pure culture but did during co-culture with P. distasonis or during mixed culture with porcine or bovine faecal microbes possessing ß-glycoside-hydrolysing activity. Fermentation acid production was reduced by thymol-ß-D-glucopyranoside treatment, indicating that fermentation was inhibited, which may limit its application to just before harvest. Results suggest that thymol-ß-D-glucopyranoside or similar ß-glycosides may be able to escape absorption within the proximal gut and become activated by bacterial ß-glycosidases in the distal gut.
Asunto(s)
Antibacterianos/farmacología , Bacterias/metabolismo , Campylobacter/efectos de los fármacos , Tracto Gastrointestinal/microbiología , Glicósidos/metabolismo , Timol/farmacología , Animales , Antibacterianos/química , Bovinos , Heces/microbiología , Fermentación , Porcinos , Timol/químicaRESUMEN
Campylobacter bacteria are foodborne pathogens that can colonize the gut of food animals. Limited in their ability to ferment sugars, Campylobacter can derive energy for growth via amino acid catabolism. The objectives of the present studies were to test whether supplemental distillers grains containing high amounts of rumen-undegradable intake protein or supplemental lasalocid may, by promoting amino acid flow to the lower bovine gut, increase intestinal carriage of Campylobacter. In study one, 10 steers (5 per treatment) were adapted to diets formulated to achieve 0 or 30% dried distillers grains. After an initial 14-day adaptation to the basal diet, control and treated steers were fed their respective diets for 23 days, after which time they were fed supplemental lasalocid for an additional 8 days, followed by a 5-day withdrawal. In study two, 24 steers preacclimated to a basal diet were adapted via 3-day periodic increases to dietary treatments formulated to achieve 0, 30, or 60% wet corn distillers grains with solubles. Analysis of Campylobacter bacteria cultured from duodenal and fecal samples in study one and from fecal samples in study two revealed no effect of dried distillers grains or wet corn distillers grains with solubles on the prevalence or concentrations of duodenal or fecal Campylobacter. The results from study one indicated that colonized steers, regardless of treatment, harbored higher Campylobacter concentrations when transitioned to the basal diet than when coming off pasture. Campylobacter carriage was unaffected by lasalocid. These results provide no evidence that feeding distillers grains high in rumen-undegradable intake protein or supplemental lasalocid contributes to increased intestinal carriage of Campylobacter in fed cattle.
Asunto(s)
Alimentación Animal/análisis , Campylobacter/crecimiento & desarrollo , Bovinos/microbiología , Lasalocido/análisis , Zea mays/química , Animales , Antibacterianos/análisis , Antibacterianos/farmacología , Campylobacter/efectos de los fármacos , Bovinos/metabolismo , Dieta/veterinaria , Heces/microbiología , Tracto Gastrointestinal/microbiología , Lasalocido/farmacologíaRESUMEN
Food-producing animals are reservoirs of Campylobacter, a leading bacterial cause of human foodborne illness. The natural product thymol can reduce the survivability of Campylobacter, but its rapid absorption in the proximal gastrointestinal tract may preclude its use as a feed additive to reduce intestinal colonization of these pathogens. This work examined the ex vivo absorption of thymol and thymol-ß-d-glucopyranoside in everted porcine jejunal segments, as the latter was hypothesized to be more resistant to absorption. A modified gas chromatography and extraction method was developed to determine 1.0-500 mg/L thymol. From 1 and 3 mM solutions, 0.293 ± 0.04 and 0.898 ± 0.212 mM thymol, respectively, p = 0.0347, were absorbed, and 0.125 ± 0.041 and 0.317 ± 0.143 mM thymol-ß-d-glucopyranoside, respectively, p = 0.0892, were absorbed. Results indicate that thymol-ß-d-glucopyranoside was absorbed 2.3 to 2.8 times less effectively than thymol, thus providing evidence that thymol-ß-d-glucopyranoside may potentially be used as a feed additive to transport thymol to the piglet lower gut.
Asunto(s)
Antiinfecciosos/metabolismo , Aditivos Alimentarios/metabolismo , Glucósidos/metabolismo , Absorción Intestinal , Yeyuno/metabolismo , Sus scrofa/metabolismo , Timol/metabolismo , Animales , Femenino , Técnicas In Vitro , Sus scrofa/crecimiento & desarrollo , Timol/análogos & derivadosRESUMEN
Food producing animals can be reservoirs of Campylobacter, a leading bacterial cause of human foodborne illness. Campylobacter spp. utilize amino acids as major carbon and energy substrates, a process that can be inhibited by thymol and diphenyliodonium chloride (DIC). To determine the effect of these potential additives on feed intake, live weight gain, and gut Campylobacter levels, growing pigs were fed standard grower diets supplemented with or without 0.0067 or 0.0201% thymol or 0.00014 or 0.00042% DIC in a replicated study design. Diets were offered twice daily for 7 days, during which time daily feed intake (mean ± SEM, 2.39 ± 0.06 kg day(-1)) and daily gain (0.62 ± 0.04 kg day(-1)) were unaffected (P > 0.05) by treatment. Pigs treated with DIC but not thymol tended to have lower rectal Campylobacter levels (P â¼ 0.07) (5.2 versus 4.2 and 4.4 log CFU g(-1) rectal contents for controls and 0.00014% DIC and 0.00042% DIC, respectively; SEM â¼ 0.26). However, DIC or thymol treatments did not affect (P > 0.05) ileal or cecal Campylobacter (1.6 ± 0.17 and 4.5 ± 0.26 log CFU g(-1), respectively), cecal total culturable anaerobes (9.8 ± 0.10 log CFU g(-1)), or accumulations of major fermentation end products within collected gut contents. These results suggest that thymol and DIC were appreciably absorbed, degraded, or otherwise made unavailable in the proximal alimentary tract and that encapsulation technologies will likely be needed to deliver effective concentrations of these compounds to the lower gut to achieve in vivo reductions of Campylobacter.
Asunto(s)
Compuestos de Bifenilo/farmacología , Campylobacter/fisiología , Contaminación de Alimentos/prevención & control , Compuestos Onio/farmacología , Porcinos/microbiología , Timol/farmacología , Alimentación Animal , Animales , Campylobacter/crecimiento & desarrollo , Campylobacter/metabolismo , Ciego/metabolismo , Ciego/microbiología , Recuento de Colonia Microbiana , Reservorios de Enfermedades/microbiología , Reservorios de Enfermedades/veterinaria , Relación Dosis-Respuesta a Droga , Heces/microbiología , Fermentación/efectos de los fármacos , Humanos , Porcinos/crecimiento & desarrollo , Porcinos/metabolismo , Aumento de PesoRESUMEN
Strategies are sought to reduce intestinal colonisation of food-producing animals by Campylobacter jejuni, a leading bacterial cause of human foodborne illness worldwide. Presently, we tested the antimicrobial activity of hydrolysable-rich blackberry, cranberry and chestnut tannin extracts and condensed tannin-rich mimosa, quebracho and sorghum tannins (each at 100 mg/mL) against C. jejuni via disc diffusion assay in the presence of supplemental casamino acids. We found that when compared to non-tannin-treated controls, all tested tannins inhibited the growth of C. jejuni and that inhibition by the condensed tannin-rich mimosa and quebracho extracts was mitigated in nutrient-limited medium supplemented with casamino acids. When tested in broth culture, both chestnut and mimosa extracts inhibited growth of C. jejuni and this inhibition was much greater in nutrient-limited than in full-strength medium. Consistent with observations from the disc diffusion assay, the inhibitory activity of the condensed tannin-rich mimosa extracts but not the hydrolysable tannin-rich chestnut extracts was mitigated by casamino acid supplementation to the nutrient-limited medium, likely because the added amino acids saturated the binding potential of the condensed tannins. These results demonstrate the antimicrobial activity of various hydrolysable and condensed tannin-rich extracts against C. jejuni and reveal that condensed tannins may be less efficient than hydrolysable tannins in controlling C. jejuni in gut environments containing high concentrations of amino acids and soluble proteins.
Asunto(s)
Aesculus/química , Antibacterianos/farmacología , Campylobacter jejuni/efectos de los fármacos , Taninos Hidrolizables/farmacología , Extractos Vegetales/farmacología , Proantocianidinas/farmacología , Rosaceae/química , Vaccinium macrocarpon/química , Infecciones por Campylobacter/microbiología , Campylobacter jejuni/crecimiento & desarrollo , Pruebas Antimicrobianas de Difusión por Disco , HumanosRESUMEN
Foodborne pathogenic bacteria such as Escherichia coli O157:H7 are threats to the safety of beef. Citrus peel and dried orange pulp are by-products from citrus juice production that have natural antimicrobial effects and are often incorporated into least-cost ration formulations for beef and dairy cattle. This study was designed to determine if orange peel and pulp affected E. coli O157:H7 populations in vivo. Sheep (n = 24) were fed a cracked corn grain-based diet that was supplemented with a 50-50 mixture of dried orange pellet and fresh orange peel to achieve a final concentration (dry matter basis, wt/wt) of 0, 5, or 10% pelleted orange peel (OP) for 10 days. Sheep were artificially inoculated with 10(10) CFU of E. coli O157:H7 by oral dosing. Fecal shedding of E. coli O157:H7 was measured daily for 5 days after inoculation, after which all animals were humanely euthanized. At 96 h postinoculation, E. coli O157:H7 shedding was reduced (P < 0.05) in sheep fed 10% OP. Populations of inoculated E. coli O157:H7 were reduced by OP treatment throughout the gastrointestinal tract; however, this reduction reached significant levels in the rumen (P < 0.05) of sheep fed 10% OP diets. Cecal and rectal populations of E. coli O157:H7 were reduced (P < 0.05) by inclusion of both 5 and 10% OP diets. Our results demonstrate that orange peel products can be used as a preharvest intervention strategy as part of an integrated pathogen reduction scheme.
Asunto(s)
Alimentación Animal , Citrus sinensis/química , Escherichia coli O157/crecimiento & desarrollo , Contaminación de Alimentos/prevención & control , Rumen/microbiología , Animales , Antibacterianos/farmacología , Bovinos , Enfermedades de los Bovinos/prevención & control , Recuento de Colonia Microbiana , Infecciones por Escherichia coli/microbiología , Infecciones por Escherichia coli/prevención & control , Infecciones por Escherichia coli/veterinaria , Escherichia coli O157/efectos de los fármacos , Heces/microbiología , Fermentación , Microbiología de Alimentos , Humanos , Ovinos , Enfermedades de las Ovejas/prevención & controlRESUMEN
Pathogenic bacteria attached to the hide or shed in the feces of cattle at slaughter can contaminate carcasses intended to be processed for human consumption. Therefore, new pre-harvest interventions are needed to prevent the carriage and excretion of foodborne pathogens in cattle presented to the processing plant. The objectives of this study were to examine the antimicrobial effects of hydrolysable tannin-rich chestnut and condensed tannin-rich mimosa extracts on bacterial indicators of foodborne pathogens when applied as a hide-intervention and as a feed additive to feedlot cattle. Water (control) or solutions (3 % wt/vol) of chestnut- and mimosa-extract treatments were sprayed (25 mL) at the left costal side of each animal to a 1000 cm² area, divided in four equal quadrants. Hide-swabs samples obtained at pre-, 2-min, 8-h, and 24-h post-spray application were cultured to enumerate Escherichia coli/total coliforms and total aerobic plate counts. In a second experiment, diets supplemented without (controls) or with (1.5 % of diet dry matter) chestnut- or mimosa-extracts were fed during a 42-day experimental feeding period. Weekly fecal samples starting on day 0, and rumen fluid obtained on days 0, 7, 21 or 42 were cultured to enumerate E.coli/total coliforms and Campylobacter. Tannin spray application showed no effect of treatment or post-application-time (P > 0.05) on measured bacterial populations, averaging 1.7/1.8, 1.5/1.6 and 1.5/1.7 (log10CFU/cm²) for E. coli/total coliforms, and 4.0, 3.4 and 4.2 (log10CFU/cm²) in total aerobes for control, chestnut and mimosa treatments, respectively. Mean (± SEM) ruminal E. coli and total coliform concentrations (log(10) CFU/mL) were reduced (P < 0.01) in steers fed chestnut-tannins (3.6 and 3.8 ± 0.1) in comparison with the controls (4.1 and 4.2 ± 0.1). Fecal E. coli concentrations were affected by treatment (P< 0.01), showing the highest values (log10 CFU/g) in fecal contents from mimosa-fed steers compared to controls (5.9 versus 5.6 ± 0.1 SEM, respectively). Total coliforms (log CFU/g) showed the highest values (P < 0.01) in feces from chestnut- and mimosa-fed steers (6.0 and 6.1 ± 0.1 respectively) in comparison with controls (5.7 ± 0.1). Fecal Campylobacter concentrations (log10CFU/g) were affected by treatment (P < 0.05), day (P < 0.001) and their interaction (P < 0.01) with the controls having lower concentrations than chestnut- and mimosa-fed steers (0.4, 1.0, and 0.8 ± 0.3, respectively). It was concluded that under our research conditions, tannins were not effective in decreasing measured bacterial populations on beef cattle hides. Additionally, chestnut tannin reduced E. coli and total coliforms within the rumen but the antimicrobial effect was not maintained in the lower gastrointestinal tract. Further research is necessary to elucidate the possible antimicrobial effects of tannins at site-specific locations of the gastrointestinal tract in beef cattle fed high-grain and high-forage diets.
Asunto(s)
Alimentación Animal/microbiología , Antiinfecciosos/farmacología , Campylobacter/efectos de los fármacos , Enterobacteriaceae/efectos de los fármacos , Carne/microbiología , Taninos/farmacología , Acacia/química , Animales , Antiinfecciosos/química , Bacterias Aerobias/efectos de los fármacos , Bovinos , Dieta/veterinaria , Fagaceae/química , Heces/microbiología , Contaminación de Alimentos/prevención & control , Masculino , Rumen/microbiología , Taninos/química , TexasRESUMEN
Salmonella is a foodborne pathogenic bacterium that causes human illnesses and morbidity and mortality in swine. Bacteriophages are viruses that prey on bacteria and are naturally found in many microbial environments, including the gut of food animals, and have been suggested as a potential intervention strategy to reduce Salmonella levels in the live animal. The present study was designed to determine if anti-Salmonella phages isolated from the feces of commercial finishing swine could reduce gastrointestinal populations of the foodborne pathogen Salmonella Typhimurium in artificially inoculated swine. Weaned pigs (n = 48) were randomly assigned to two treatment groups (control or phage-treated). Each pig was inoculated with Salmonella Typhimurium (2 × 10(10) colony forming units/pig) via oral gavage at 0 h and fecal samples were collected every 24 h. Swine were inoculated with a phage cocktail via oral gavage (3 × 10(9) plaque forming units) at 24 and 48 h. Pigs were humanely killed at 96 h, and cecal and rectal intestinal contents were collected for quantitative and qualitative analysis. Fecal Salmonella populations in phage-treated pigs were lower (p < 0.09) than controls after 48 h. Phage treatment reduced intestinal populations of inoculated Salmonella Typhimurium in pigs compared to controls at necropsy. Cecal populations were reduced (p = 0.07) by phage treatment >1.4 log(10) colony forming units/g digesta, and rectal populations were numerically reduced. The number of pigs that contained inoculated Salmonella Typhimurium was reduced by phage treatment, but a significant (p < 0.05) reduction was only observed in the rectum. We conclude that phages can be a viable tool to reduce Salmonella in swine. Further research needs to be performed to determine the most efficacious dosing regimens and the most effective combinations of phages targeting the diverse Salmonella population found in swine before they can enter the food supply.
Asunto(s)
Control Biológico de Vectores/métodos , Salmonelosis Animal/prevención & control , Fagos de Salmonella/fisiología , Salmonella typhimurium/crecimiento & desarrollo , Salmonella typhimurium/virología , Sus scrofa/microbiología , Crianza de Animales Domésticos/métodos , Animales , Derrame de Bacterias , Bacteriólisis , Ciego/microbiología , Recuento de Colonia Microbiana/veterinaria , Heces/microbiología , Contenido Digestivo/microbiología , Humanos , Viabilidad Microbiana , Recto/microbiología , Intoxicación Alimentaria por Salmonella/prevención & control , Salmonelosis Animal/microbiología , Salmonelosis Animal/virología , Salmonella typhimurium/aislamiento & purificación , Salmonella typhimurium/fisiología , Sus scrofa/crecimiento & desarrollo , Sus scrofa/virología , Factores de TiempoRESUMEN
Ruminal methanogenesis is considered a digestive inefficiency that results in the loss of 2-12% of the host's gross energy intake and contributes nearly 20% to the United States annual CH(4) emissions. Presently, the effects of the known CH(4) inhibitor, nitroethane, and two synthetic nitrocompounds, dimethyl-2-nitroglutarate and 2-nitro-methyl-propionate, on ruminal CH(4) production and fermentation were evaluated in vitro. After 24 h incubation at 39 degrees C under 100% CO(2), ruminal fluid cultures treated with 2.97 or 11.88 mumol ml(-1) of the respective nitrocompounds produced > 92% less CH(4) (P < 0.05) than non-treated controls. Quantification of fermentation end-products produced and H(2) balance estimates indicate that fermentation efficiencies were not compromised by the nitro-treatments.
Asunto(s)
Etano/análogos & derivados , Fermentación , Glutaratos/química , Hidrógeno/química , Metano/química , Nitroparafinas/química , Propionatos/química , Animales , Dióxido de Carbono/química , Bovinos , Etano/química , Ácidos Grasos/química , Gases , Técnicas In Vitro , Medicago sativa/metabolismo , Compuestos de Nitrógeno/química , Rumiantes , TemperaturaRESUMEN
Experiments were conducted to determine factors that affect sensitivity of Salmonella enterica serovar Typhimurium to sodium chlorate (5mM). In our first experiment, cultures grown without chlorate grew more rapidly than those with chlorate. An extended lag before logarithmic growth was observed in anaerobic but not aerobic cultures containing chlorate. Chlorate inhibition of growth during aerobic culture began later than that observed in anaerobic cultures but persisted once inhibition was apparent. Conversely, anaerobic cultures appeared to adapt to chlorate after approximately 10h of incubation, exhibiting rapid compensatory growth. In anaerobic chlorate-containing cultures, 20% of total viable counts were resistant to chlorate by 6h and had propagated to 100% resistance (>10(9)CFU mL(-1)) by 24h. In the aerobic chlorate-containing cultures, 12.9% of colonies had detectable resistance to chlorate by 6h, but only 1% retained detectable resistance at 24h, likely because these cultures had opportunity to respire on oxygen and were thus not enriched via the selective pressure of chlorate. In another study, treatment with shikimic acid (0.34 mM), molybdate (1mM) or their combination had little effect on aerobic or anaerobic growth of Salmonella in the absence of added chlorate. As observed in our earlier study, chlorate resistance was not detected in any cultures without added chlorate. Chlorate resistant Salmonella were recovered at equivalent numbers regardless of treatment after 8h of aerobic or anaerobic culture with added chlorate; however, by 24h incubation chlorate sensitivity was completely restored to aerobic but not anaerobic cultures treated with shikimic acid or molybdate but not their combination. Results indicate that anaerobic adaptation of S. Typhimurium to sodium chlorate during pure culture is likely due to the selective propagation of low numbers of cells exhibiting spontaneous resistance to chlorate and this resistance is not reversible by molybdenum supplementation.
Asunto(s)
Cloratos/farmacología , Farmacorresistencia Bacteriana , Molibdeno/farmacología , Salmonella typhimurium/efectos de los fármacos , Ácido Shikímico/farmacología , Aerobiosis , Anaerobiosis , Recuento de Colonia Microbiana , Humanos , Viabilidad Microbiana , Salmonella typhimurium/crecimiento & desarrollo , Salmonella typhimurium/metabolismo , Factores de TiempoRESUMEN
Indole and 3-methylindole (skatole) are odor pollutants in livestock waste, and skatole is a major component of boar taint. Skatole causes pulmonary edema and emphysema in ruminants and causes damage to lung Clara cells in animals and humans. A gas chromatographic method that originally used a nitrogen-phosphorus detector to increase sensitivity was modified resulting in an improved flame ionization detection response for indole and skatole of 236% and 207%, respectively. The improved method eliminates the large amount of indole decomposition in the injector. A 10 micro g mL(-1) spike of indole and skatole in water and swine fecal slurries resulted in recovery of 78.5% and 96% in water and 76.1% and 85.8% in fecal slurries, respectively. The effect of the addition of nitroethane and nitroethanol at 21.8 mM in swine fecal slurries was studied on the microbial production of indole and skatole. Nitroethane and nitroethanol decreased the production of skatole in swine fecal slurries at 24 h. The nitroethane effect on l-tryptophan-supplemented fecal slurries after 6 and 24 h incubation resulted in a decrease of 69.0% (P = 0.02) and 23.5% skatole production, respectively, and a decrease of 14.9% indole at 6 h, but an increase in indole production of 81.1% at 24 h.
Asunto(s)
Bacterias/efectos de los fármacos , Bacterias/metabolismo , Cromatografía de Gases/métodos , Etano/análogos & derivados , Etanol/análogos & derivados , Heces/microbiología , Indoles/metabolismo , Nitroparafinas/farmacología , Escatol/metabolismo , Porcinos/microbiología , Animales , Cromatografía de Gases/instrumentación , Etano/farmacología , Etanol/farmacología , Factores de Tiempo , Triptófano/metabolismoRESUMEN
Campylobacter are important human foodborne pathogens known to colonize the gastrointestinal tract of cattle. The incidence of Campylobacter in cattle may be seasonal and may vary among age groups and type (beef versus dairy). Less is known about other factors that could influence the prevalence, colonization site, and shedding of Campylobacter in cattle. The objectives of this study were to evaluate the prevalence and enumerate Campylobacter at two sites along the digestive tract of beef and dairy type cattle consuming either grass or feedlot diets. In an initial study, Campylobacter was not recovered from rumen samples of any of 10 ruminally cannulated (six dairy and four beef type) pasture-reared cattle and there was no difference (p > 0.05) between cattle types on fecal Campylobacter recovery, with 50% of each type yielding culture-positive feces (overall mean +/- SE, 0.75 +/- 0.001 SEM log(10) colony-forming units [CFU]/g feces). When calculated from Campylobacter culture-positive animals only, mean fecal concentrations were 1.50 +/- 0.001 SEM log(10) CFU/g. In a follow-up study with feedlot and pasture-reared cattle (n = 18 head each), 78% of rumen and 94% of fecal samples from pastured cattle were positive for Campylobacter while 50% of the rumen and 72% of the fecal samples were positive in concentrate-fed animals. Overall mean concentration of Campylobacter was greater in feces than ruminal fluid (p < 0.05). When only Campylobacter-positive animals were analyzed, concentrations recovered from feces were higher (p < 0.05) in concentrate-fed than in pasture-fed cattle (4.29 vs. 3.34 log(10) CFU/g, respectively; SEM = 0.29). Our results suggest that the rumen environment and its microbial population are less favorable for the growth of Campylobacter and that concentrate diets may provide a more hospitable lower gastrointestinal tract for Campylobacter.
Asunto(s)
Campylobacter/crecimiento & desarrollo , Bovinos/microbiología , Dieta/veterinaria , Heces/microbiología , Rumen/microbiología , Análisis de Varianza , Alimentación Animal , Animales , Campylobacter/genética , Infecciones por Campylobacter/microbiología , Infecciones por Campylobacter/veterinaria , Enfermedades de los Bovinos/microbiología , Recuento de Colonia Microbiana , ADN Bacteriano/genética , Ecología , Femenino , Microbiología de Alimentos , Masculino , PrevalenciaRESUMEN
Ruminal methane (CH(4)) production results in the loss of up to 12% of gross energy intake and contributes nearly 20% of the United States' annual emission of this greenhouse gas. We report the effects of select nitrocompounds on ruminal fermentation after 22 h in vitro incubation (39 degrees C) with or without additions of hydrogen (H(2)), formate or both. In incubations containing no added reductant, CH(4) production was inhibited 41% by 2-nitro-1-propanol (2NPOH) and >97% by 3-nitro-1-propionic acid (3NPA), nitroethane (NE) and 2-nitroethanol (2NEOH) compared to non-treated controls and H(2) did not accumulate. With formate as the sole added reductant, nitro-treatment reduced CH(4) production by >99% and caused 42% to complete inhibition of formate catabolism compared to controls, and the accumulation of H(2) increased slightly. Nitro-treatment decreased CH(4) production 57-98% from that of controls when supplied H(2) or formate plus H(2). Formate catabolism was decreased 42-84% from that in controls by all nitro-treatments except 3NPA with both formate and H(2). Greater than 97% of the added H(2) was catabolized within controls; >84% was catabolized in nitro-treated incubations. Acetate, propionate and butyrate accumulations were unaffected by nitro-treatment irregardless of reductant; however, effects on ammonia and branched chain fatty acid accumulations varied. These results suggest that nitro-treatment inhibited formate dehydrogenase/formate hydrogen lyase and hydrogenase activity.
Asunto(s)
Fermentación/efectos de los fármacos , Nitrocompuestos/farmacología , Sustancias Reductoras/farmacología , Rumen/efectos de los fármacos , Acetatos/análisis , Amoníaco/análisis , Animales , Bovinos , Ácidos Grasos Volátiles/análisis , Metano/metabolismo , Nitrocompuestos/metabolismo , Oxidación-Reducción/efectos de los fármacos , Propionatos/análisis , Rumen/microbiologíaRESUMEN
Nitroethane is a potent inhibitor of ruminal CH 4 production, a digestive inefficiency resulting in the loss of 2-15% of a ruminant's gross energy intake and an important emission source of this greenhouse gas. To assess the effect of nitroethane on methanogenesis and characterize ruminal adaptation observed with low treatment doses to this inhibitor, ruminal microbes were cultured in vitro with supplements of water (controls), 4.5 and 9 mM nitroethane, and 0.09 mM monensin, with or without 9 mM nitroethane. All treatments decreased CH 4 production >78% compared to controls; however, differential effects of treatments were observed on CO 2, butyrate isobutyrate, and valerate production. Treatments did not affect H 2 accumulation or acetate and propionate production. Most probable numbers of nitrometabolizing bacteria were increased with 4.5 and 9 mM nitroethane compared to numbers recovered from controls or monensin-containing treatments, which may explain ruminal adaptation to lower nitroethane treatments.