A comparison between longitudinal shedding patterns of Salmonella Typhimurium and Salmonella Dublin on dairy farms

Salmonella in cattle herds may behave as epidemic or endemic infections. An intensive longitudinal sampling study across all management groups and ages on six dairy farms in the UK was used to examine patterns of Salmonella shedding, following the prior identification of either Salmonella Dublin (SD) (three farms) or Salmonella Typhimurium (ST) (three farms) on the premises in the context of clinical salmonellosis. Individual faeces, pooled faeces and environmental samples (total 5711 samples), taken approximately every six weeks for 15-24 weeks, were cultured for Salmonella. SD was detected at low frequency (on any visit, 0.5-18.3 per cent of samples positive) and most consistently in calves. By contrast, ST was isolated at higher frequency (on any visit, 6.8-75 per cent of samples positive), and in higher numbers, up to 10(7) cfu/g faeces. Significantly more samples from calves were positive for ST than were positive for SD (50.6 per cent v 3.1 per cent; P?相似文献   

Fecal shedding of Salmonella spp by horses in the United States during 1998 and 1999 and detection of Salmonella spp in grain and concentrate sources on equine operations

OBJECTIVE: To estimate prevalence of fecal shedding of Salmonella spp among horses in the US horse population and prevalence of Salmonella spp in grain or other concentrate used as horse feed on equine operations in the United States. DESIGN: Cross-sectional survey. SAMPLE POPULATION: Horses on 972 operations in 28 states. PROCEDURE: Fecal samples were collected from horses resident at each operation. Only a single sample was collected from any individual horse; number of horses from which samples were collected on each operation was determined on the basis of number of horses on the operation. A single sample of grain or concentrate was also collected from each operation. All samples were tested for Salmonella spp by means of bacterial culture. RESULTS: Overall, 0.8% (SE, 0.5) of resident horses shed Salmonella spp in their feces. The overall prevalence of operations positive for fecal shedding of Salmonella spp (i.e., operations with > or = 1 horse shedding Salmonella spp in its feces) was 1.8% (SE, 0.7). Prevalence of grain or other concentrate samples positive for Salmonella spp was 0.4%. Serotypes of Salmonella spp that were identified in grain or other concentrate were not those typically associated with clinical disease in horses. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the national prevalence of fecal shedding of Salmonella spp by horses in the United States was 0.8%, and that prevalence of Salmonella spp in grain or other concentrate used for horse feed was 0.4%.     

Occurrence of Salmonella serotype Typhimurium DT104 on a commercial swine farm before, during, and after depopulation and repopulation

OBJECTIVE: To determine whether depopulation-repopulation could be used to eradicate Salmonella serotype Typhimurium DT104 from a commercial swine farm in the midwestern United States. DESIGN: Observational study SAMPLE POPULATION: A commercial swine farm undergoing depopulation-repopulation to eliminate porcine reproductive and respiratory syndrome virus and Mycoplasma hyopneumoniae. PROCEDURE: Pooled fecal samples, tissue samples, and serum samples were collected from pigs on the farm before and after depopulation-repopulation. When there were no pigs on the farm, environmental swab specimens were collected for bacterial culture. Serum was analyzed for anti-Salmonella antibodies with an indirect ELISA. Salmonella isolates obtained by bacterial culture of fecal, tissue, and environmental samples were characterized by means of serotyping, phage typing, pulsed-field gel electrophoresis (PFGE), and antimicrobial susceptibility testing. RESULTS: 167 Salmonella isolates representing 9 serotypes were recovered from the farm. Results of PFGE and antimicrobial susceptibility testing suggested that S. Typhimurium DT104 strain was not eradicated from the farm. However, seroprevalence of anti-Salmonella antibodies and the percentage of pooled fecal samples positive for Salmonella spp were significantly decreased following repopulation. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that depopulation-repopulation in conjunction with stringent cleaning and disinfection, attention to biosecurity procedures, control of other diseases, and changes in feed management may reduce the occurrence of, but likely will not eliminate, Salmonella spp in commercial swine herds.     

Resynchronization with the G6G protocol: A retrospective,observational study of second and later timed artificial inseminations on commercial dairy farms

We recorded conception rates and estimated pregnancy rates following second and later timed artificial inseminations (TAIs) after hormonal resynchronization on commercial dairy farms, using the so‐called G6G protocol (PGF day‐0; GnRH 2, 8 days; PGF 15, 16 days, GnRH 17 days; TAI 18 days), and the 5‐day Ovsynch protocol or 5DO (GnRH day 0; PGF 5, 6 days; GnRH 7 days; TAI 8 days). In four farms, both protocols were implemented in parallel, and these 1,368 s and later TAIs were used for the protocols’ comparison based on logistic regression (544 TAIs in primiparous; 824 in multiparous cows; 1,024 TAIs after G6G [600 TAIs in multiparous and 424 in primiparous]; 344 TAIs after 5DO [224 TAIs in multiparous and 120 in primiparous]; 280 TAIs during the hot season; 1,088 during the cool season). Conception rate (CR) was 31.7% ± 12.0% among all cows, 35.1% ± 10.7% among cows resynchronized with the G6G protocol and 21.8% ± 9.7% among cows resynchronized with the 5DO protocol (p < 0.0001). CR among all cows was lower during the hot season (19.3% ± 8.4%) than during the cool season (34.9% ± 10.6%; p < 0.0001), and similar seasonal results were observed with G6G protocols. Logistic regression showed significant effects on CR in second and later TAIs by protocol (OR = 0.514; 95% CI 0.385–0.686; p < 0.0001) and season (OR = 0.486; 95% CI 0.350–0.676; p < 0.0001). Parity did not influence CR after second and later TAIs (p > 0.1), and no interaction with season or resynchronization protocol was found. Estimated pregnancy rates based on these CR data from both hormonal protocols suggest that G6G can be effectively used for second and later TAIs and highlight the importance of considering protocol and season when designing strategies for second and later timed AIs on dairy farms.     

An observational study on the prevalence and impact of Isospora suis in suckling piglets in southwestern Ontario, and risk factors for shedding oocysts

An observational study was conducted to determine the prevalence of Isospora suis oocysts in fecal samples from suckling piglets in Ontario, and to evaluate the relationship between the presence of I. suis oocysts and diarrhea. Fifty farms and 709 litters of piglets were included in the study. Oocysts were detected on 70% of farms, with 187 litters infected. A litter of pigs that was positive for oocysts was significantly more likely to exhibit diarrhea than a litter that was negative [odds ratio (OR) = 4.0; 95% confidence interval (CI) = 2.8 to 5.8; P < 0.001]. Management and housing factors were examined with respect to risk factors for the presence of I. suis. Farms that did not use a detergent when cleaning farrowing crates were 10-times more likely to be positive for I. suis than those that used a detergent (P = 0.007). It was concluded that coccidiosis is a common problem on Ontario swine farms.     

Antibiotic resistance of members of the genus Salmonella isolated from chickens, turkeys, cattle, and swine in the United States during October 1981 through September 1982

Members of the genus Salmonella isolated from chickens, turkeys, cattle, and swine and submitted to the National Veterinary Services Laboratories for serotyping during October 1981 through September 1982 were tested for sensitivity to 12 antibacterial drugs. A total of 3,500 isolates was tested. A high rate of drug resistance was observed. Three cultures were resistant to each of the drugs and 30% were resistant to each drug except chloramphenicol, cephalothin, and gentamicin. Multiple resistance patterns were observed for 80% of the cultures with an even higher percentage in cultures from swine.     

Effect of organic acids in drinking water during the last 2 weeks prior to slaughter on Salmonella shedding by slaughter pigs and contamination of carcasses

In this study, we investigated the effect of adding organic acids to the drinking water of finishing pigs 2 weeks prior to slaughter on the shedding and prevalence rate of Salmonella at slaughter. Approximately 600 animals from four Belgian pig herds infected with Salmonella were included. At two herds, the study was conducted twice. Before the start of the study, overshoes were taken at the different herds. Two weeks prior to the expected slaughter date, the pigs were randomly divided into two groups (treatment and control group) each containing on average 50 animals within each herd. The treatment group received from this day onwards acidified drinking water (pH = 3.6-4.0), the control group received non-treated water (pH = 7.8-8.5). All other housing, feeding and management factors were identical in both groups. At the slaughterhouse, 10 pigs of each group (20 pigs for each group of study group 6) were randomly selected and sampled (blood, contents of ileum and rectum, mesenteric lymph nodes and carcass swabs). All samples were immediately transported to the laboratory and submitted to Salmonella isolation. Salmonella was isolated out of 11.9% (66/554) of the samples taken at the slaughterhouse, with the highest frequency found in the content of the ileum (18.7%), followed by 17.8% in the lymph nodes, 7.2% in the content of the rectum and 3.6% in the carcass swabs. The results did not reveal a significant difference between the treatment and control groups for the different slaughterhouse samples. The study documented that the investigated control strategy namely, the strategic application of organic acids during the last 2 weeks prior to slaughter was insufficient to decrease Salmonella shedding and contamination shortly before and during slaughter.     

A questionnaire-based,retrospective field study of persistence of Salmonella Enteritidis and Salmonella Typhimurium in Danish broiler houses

A questionnaire-based, retrospective field study was conducted in 78 Danish broiler houses (analytical units) on 42 farms. In spring 1997, all these broiler houses had been infected with Salmonella Enteritidis, phage type 8, and/or Salmonella Typhimurium, definitive-type 66, by day-old chicks delivered from the same hatchery. Because these two salmonella types had not been detected in the Danish broiler sector before and the broiler houses were infected in a period of low salmonella prevalence, the study could focus on farm-related factors, without being distorted by other salmonella infections.

The same person visited all 78 broiler houses, and farm-related factors were listed both from personal observations and by interrogating the person in charge of attending to the broilers. Additional factors (noted at the visits) were recorded in a later telephone interview. Altogether, 187 variables were analyzed.

Broiler houses were divided into single-infection houses (which had one or both of the salmonella types in only one crop), and multiple-infection houses (where infection occurred in multiple crops). This was done both generally and separately for each of the salmonella types.

Factors associated with house status—but that were beyond the control of the farmer—were the salmonella type and the percentage of salmonella positive samples in the first crop. Factors which could be controlled by the farmer and which were associated with reduced prevalence of multiple-infection houses included antiseptic soap and water for washing hands in the anteroom, hygiene barriers when removing dead broilers, gravel alongside the broiler house, systematic checks of indoor rodent-bait depots, and combined surface and pulse-fogging disinfection.     

A study of the distribution patterns and levels of Salmonella enteritidis in the immune organs of ducklings after oral challenge by serovar-specific real-time PCR

The objective of this study was to understand the distribution patterns and levels of Salmonella Enteritidis (SE) in the immune organs of ducklings after oral challenge. We conducted serovar-specific real-time polymerase chain reaction (PCR) for SE to detect the genomic DNA of SE in the blood and immune organs, including the bursa of Fabricius, thymus, spleen, and Harderian gland, from ducklings after oral challenge at different time points. The results showed that SE was consistently detected in all the samples. The Harderian gland and spleen tested positive at 8 hr postinoculation (PI). The organism was detected in the blood, bursa of Fabricius, and thymus at 10 hr PI. The copy number of SE DNA in each tissue reached a peak at 24-36 hr PI. The spleen, blood, and Harderian gland contained high concentrations of SE, whereas the thymus and bursa of Fabricius had low concentrations. SE populations began to decrease and were not detectable at 2 days PI, but they were still present up to 9 days PI in the spleen, without producing any apparent symptoms. To validate these results, the indirect immunofluorescent antibody (IFA) technique was used, and the IFA results were similar to those of the fluorescent quantitative-PCR. In conclusion, the results provided insight into the SE life cycle in the immune organs; furthermore, the Harderian gland and spleen were determined to be the primary sites of invasion among the immune organs of normal ducklings after oral SE challenge. This study will help in understanding the pathogenesis of SE infection in vivo and may help in the development of a live Salmonella vaccine in the future.     

A longitudinal study of sows and boars raised by smallholder farmers in the Philippines

We conducted a longitudinal study to obtain baseline information about the health and productivity of sows and boars raised by smallholder-pig raisers in the Philippines, and test constraints and opportunities to smallholder-sow production that had been identified previously in a cross-sectional study [More, S.J., Lee, J.-A.L.M., La?ada, E.B., Taveros, A.A., Cotiw-an, B.S., 1999. Weight-for-age of growing pigs raised by smallholder farmers in the Philippines. Prev. Vet. Med. 41, 151-169]. Over 12-18 months, we collected data during monthly on-farm visits about 213 sows raised in 119 herds at 2 sites and 32 boars in 31 herds at 1 site. Sow reproductive performance was low and boars were used only infrequently (an average of 0.9 services/month). Using repeated-measure analyses, we identified sow nutrition and piglet care (such as provision of creep feed and unrestricted access to the sow) as important husbandry issues associated with increased sow productivity.     

Saliva chromogranin A in growing pigs: A study of circadian patterns during daytime and stability under different storage conditions

Salivary chromogranin A (CgA) is considered to be a biomarker of activation of the sympatho-adrenomedullary system, and has recently been proposed as a useful indicator of the acute stress response in pigs. The aim of the present study was to determinate whether salivary CgA concentrations in healthy growing pigs exhibits any circadian pattern during the daytime, and to evaluate its stability under different storage conditions. A total of 80 pigs (40 in spring and another 40 in autumn) of two different ages and genders were used. To establish the circadian pattern, saliva samples were collected at 07.00, 11.00, 15.00 and 19.00 h on two consecutive days. Pooled samples were used for the stability study and were measured on the day of sampling and periodically for up to 360 days later. Samples were stored at 4 °C, ?20 °C or ?80 °C and the effect of repeated freezing and thawing was also evaluated.No circadian pattern was detected for salivary CgA in either season and there were no significant effects of gender or age. However, mean salivary CgA concentrations were significantly higher (P < 0.0001) in the pigs sampled in autumn, compared to those sampled in the spring. Short term storage at 4 °C is recommended for up to 2 days, whereas frozen samples can be stored for 1 year at ?20 °C or ?80 °C, without substantial reduction in CgA values. In addition, samples can be frozen and thawed up to seven times without significant loss of the biomarker.     

A survey of nematode control measures used by milking goat farmers and of anthelmintic resistance on their farms

Forty-seven milking goat herds, located throughout New Zealand, were surveyed for anthelmintic usage and for gastrointestinal nematodes resistant to anthelmintics. Most farmers (62%) followed a predetermined drenching programme and usually (68%) had a policy of alternating between drench families. Alternation was generally within the farming year. Kids were on average being drenched 12.5 times during their first year (range 2-34). Does aged greater than one year were all being drenched at the same frequency (average 13.4, range 2-34) irrespective of age. On each of the 47 farms, a group of goats was treated with a benzimidazole (BZ) drench (oxfendazole, OFZ, at 4.5 mg/kg on 36 farms and thiabendazole, TBZ at 66 mg/kg on 11 farms); a second group was treated with a "cell membrane depolarizing" (CMD) drench (levamisole, LEV, at 8 mg/kg on 35 farms and morantel citrate, MOR, at 10 mg/kg on 12 farms); a third group remained untreated as controls. Faecal egg counts and larval cultures were done before dosing and one week later. Faecal egg count depressions of <80% were taken as being suggestive of anthelmintic resistance. On this basis resistance was found on 79% of farms surveyed. Resistance to BZs alone occurred on 36% of farms, resistance to CMDs alone on 4% and resistance to both on 38% of farms. On 23% of farms one or other of the drenches was without any apparent effect and on one farm both of the drenches tested failed to reduce the egg counts. Post-drenching larval cultures showed Trichostrongylus, Haemonchus and Ostertagia to be the most prevalent genera remaining after drenching with BZ on 14,11, and 8 farms, respectively. After drenching with LEV Ostertagia was the dominant species on 10 farms, Trichostrongylus on 2 and on one farm the two genera were equally common. Following treatment with MOR Trichostrongylus was the dominant species on 3 farms, Haemonchus on 2 and on one farm Trichostrongylus and Ostertagia were equally common. There was a positive association between drenching frequency and the presence of resistance on farms. Possible interpretations of this association are discussed.     

A longitudinal study of Escherichia coli strains isolated from captive mammals, birds, and reptiles in Trinidad.

A longitudinal study was conducted of the prevalence and characteristics of Escherichia coli in mammals, birds, and reptiles housed at the Emperor Valley Zoo, Trinidad. During a 6-mo study period, swabs were obtained from fecal samples that were randomly collected from the enclosures of animals from these three taxonomic groups every 3 wk. With snakes, both cloacal and fecal swabs were obtained. Fecal and cloacal swabs were cultured for E. coli on eosin methylene blue agar. The production of mucoid colonies and hemolytic colonies and non-sorbitol fermenter status were identified. The occurrence of O157 strains was determined amongst E. coli isolates that were non-sorbitol fermenters, and the disc diffusion method was used to determine the antibiograms of isolates. The frequency of E. coli isolation was significantly higher in mammals compared with birds and reptiles. Overall, the frequencies of isolation of E. coli from omnivores. herbivores, and carnivores, 87.2%, 70.0%, and 57.3%, respectively, regardless of animal class, were significantly different. Most (99.6%) of the E. coli isolates tested for antibiotic sensitivity exhibited resistance to one or more of the eight antimicrobial agents used. The possession of phenotypic virulence markers by the E. coli isolates studied and the generally high resistance to antimicrobial agents may have health implications for the zoological collection.     

Variations in plasma prolactin, thyroid hormones, gonadal steroids and growth hormone in turkeys during the induction of egg laying and moult by different photoperiods.

1. Concentrations of prolactin, growth hormone, testosterone, progesterone, thyroxine and triiodothyronine were measured in the blood plasma of female turkeys during successive periods of egg laying, a decline in lay, a moult induced by a short photoperiod (6 light: 18 dark) and a resumption of egg laying induced by a long photoperiod (16L:8D). 2. Concentrations of prolactin, growth hormone, testosterone and progesterone were higher in laying birds than in birds which were moulting or not laying. 3. The concentration of testosterone, but not of the other hormones studied, increased significantly during the period of profuse moult. 4. Concentrations of the thyroid hormones did not change with the varying physiological condition of the birds. However, the concentration of thyroxine was depressed by the long photoperiod.     

A longitudinal study of veterinary students and recent graduates: 1. Backgrounds, plans and subsequent employment

Objective To examine factors that influence career choies by veterinary graduates.
Design Longitudinal study.
Population Students – 77 female and 77 males - who began studying veterinary science at The University of Queensland in 1985 and 1986.
Procedure Questionnaires were completed in the first and fifth year of the course, and in the second year after graduation. The data were arranged into an aggregated data set, then analysed using the SAS System for Windows.
Results These students chose veterinary science, many cases at an early age, because of their attitude towards animals rather than advice from other people. Most had extensive experience with animals, and many gained this in cities rather than on farms. Between half and two-thirds of them looked forward to a career in private practice when they were in first year. The proportion planning a career in private practice was highest for those who chose veterinary science before they were 12 years old. One-quarter of those in first year were undecided about what they would do after graduation. When they were surveyed in fifth year, most planned to enter mixed private practice at least initially. In fact, 59% entered mixed practice and 28% small animal practice. There were no significant relationships between prior experience with animals and either career plans or success in the job market. When asked in their second year after graduation, about half planned to continue in private practice over the longer term, and a quarter were undecided.
Conclusions The decision to study veterinary science is often made at a young age, and is influenced mainly by attitudes towards animals. The career path planned by the majority involves private practice, but for about a quarter the future is unclear, both when they enter the course and after they have worked as veterinarians.