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1.
Digests of diaphragms from 33 482 hogs slaughtered in the mid-atlantic states were examined for the presence of Trichinella spiralis larvae. The samples were obtained from 7 slaughterhouses, ranging in slaughter capacity from less than 50 per day to more than 4000 per day. The sources of the hogs varied from “backyard” operations, raising hogs for home use, to commercial farms. The means by which hogs were brought to the slaughterhouse also differed; the larger slaughterhouses often purchased directly from the producer while the smaller slaughterhouses (1000 hogs per day or less) usually purchased through dealers or brokers. Infected hogs were detected more frequently than was expected from previously-published prevalence studies; overall, 0.58% of samples examined contained T. spiralis larvae. All of the infected hogs were marketed through the smaller slaughterhouses (less than 1000 per day) and nearly all were marketed through brokers. The mean number of larvae per gram of diaphragm, determined by slaugterhouses type, ranged from 0.5 to 74.6; most infections were light although 5 had counts of 1000–2480.Most of the positive samples were obtained from one slaughterhouse, the data from which exhibited marked differences in the frequency of infection by day of the week; 128 positive samples of the total of 190 found were obtained on Fridays, although only 10% of all samples were obtained on that day. Analysis of the geographic origin of shipments containing infected hogs revealed that most originated in New Jersey and Pennsylvania, although the hogs shipped from the latter state might originated in New England or Maryland. Attempts to trace back infected hogs for further epidemiological investigation were largely futile, owing to the absence of an identification system.  相似文献   

2.
The levels of production, ascarid burden and respiratory disease were measured on 15 purposively selected swine herds, and the relationships between the various measures of ascarid burden were examined. On each farm 30 randomly selected pigs were weighed and rectal fecal samples were collected at approximately 11, 15, 19 and 22 weeks of age, and at slaughter. Fecal ascarid-egg counts and duration of infection were combined to calculate a composite measure of ascarid burden called "lifetime burden". At the abattoir the carcass weight and levels of anteroventral pneumonia, atrophic rhinitis, and liver lesions were recorded for each hog. The number of ascarids in the small intestines were counted. Study hogs were marketed at an average of 189 +/- 22 days. The average dressed carcass weight was 77.0 +/- 5.9 kg and the mean average daily gain was 0.519 +/- 0.071 kg/day. The percent of hogs with ascariasis varied widely among farms, no matter what measure of ascariasis was used; the percent with intestinal ascarids at slaughter ranged from 0% to 96%, the percent that shed ascarid eggs during their lifetime ranged from 0% to 100%, and the range for hogs with liver lesions ranged from 27% to 100%. Of the hogs slaughtered, 82% had milk spot lesions, 32% shed ascarid eggs during their lifetime and 35% had intestinal ascarids. The latter had an average of 12 intestinal ascarids. Anteroventral pneumonia occurred in 55% of the slaughtered hogs and 9% had atrophic rhinitis scores of five. The percent of hogs per farm with pneumonia ranged from 17% to 96%. The percent of hogs per farm with atrophic rhinitis scores of five ranged from 0% to 57%.  相似文献   

3.
A field evaluation of an enzyme-linked immunosorbent assay (ELISA) for swine trichinosis was done with sera obtained from 5 herds experiencing ongoing transmission of Trichinella spiralis. Epizootiologic studies conducted on these herds offered an opportunity to evaluate the accuracy of an ELISA, using larval T spiralis excretory-secretory antigens. Sera from 162 infected pigs and 143 serum samples from noninfected pigs originating from the same farms were tested. The infection status of the pigs was determined by digestion of diaphragm or tongue muscle samples. Two criteria were established to classify the ELISA optical density (OD) readings: Criterion I stated that an OD greater than or equal to 5 times the mean OD of several normal swine sera pools was positive; criterion II stated that a OD greater than or equal to 4 times the normal sera values was positive. The results obtained did not reveal obvious serologic variations among infected herds located in the 4 states involved. Overall, the test detected 93% (criterion I) and 96% (criterion II) of infected pigs. The majority of false-negative sera was from hogs that had less than 5 larvae/g of muscle; 1 hog had 73.8 larvae/g of diaphragm muscle. The false-positive rates were 8% for criterion I and 9% for criterion II. The actual rate for these false-positive samples may have been overestimated, because generally, only small tissue samples (0.4 to 10 g) were digested; larger sample sizes might have altered the results. The relevance of this qualification is that these pigs originated from herds with prevalence rates greater than 50%. Other factors that may account for occasional false-positive sera or false-negative sera in the swine trichinosis ELISA are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

4.
Seventy market-weight hogs (90 to 113 kg) were used in a feeding study to determine the correlation of serum sulfamethazine concentrations with sulfamethazine concentrations in liver and muscle at time of slaughter. Test groups were fed medicated feeds prepared from commercial medicated premixes containing 110 g of sulfamethazine/metric ton for 30 days. Fifteen days before hogs were slaughtered, test groups were given maintenance feeds containing 1.1 to 13.9 g of sulfamethazine/metric ton and were fed these diets until slaughtered. Comparison of data from positive- and negative-control groups indicated that total withdrawal of sulfamethazine in the feed was not necessary for the liver to contain less than the allowed tolerance of 0.1 mg of sulfamethazine/kg of liver at slaughter. Feed concentrations of up to 2 g of sulfamethazine/metric ton could be tolerated in withdrawal feeds before liver sulfamethazine values exceeded 0.1 mg/kg of liver. Serum/tissue sulfamethazine ratios were erratic in hogs given 1.1 to 2.7 g of sulfamethazine/metric ton, but became less variable in hogs given greater than 5.7 g/metric ton. Feed concentrations greater than 8 g of sulfamethazine/metric ton produced values greater than 0.1 mg/kg of muscle and values of about 0.4 mg/kg of liver. When serum sulfamethazine concentrations alone were used as a predictor for tissue sulfamethazine values, 100% of the liver values exceeded 0.10 mg/kg of liver when sulfamethazine in serum was greater than 0.45 mg/L. However, 57.4% of samples having serum concentrations between 0.10 and 0.45 mg/L had associated sulfamethazine values greater than 0.1 mg/kg of liver. All hogs having serum sulfamethazine concentrations less than 0.1 mg/L had sulfamethazine concentrations less than 0.1 mg/kg of liver.  相似文献   

5.
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6.
The prevalence of paratuberculosis in culled New England cattle   总被引：4，自引：0，他引：4  
The prevalence of bovine paratuberculosis in New England was determined to be 18% based on a random survey of abattoir cattle. Six tissues from each of 100 animals were examined by histologic and bacteriologic methods. The cecal lymph node and the ileocecal valve yielded positive cultures most frequently, but isolations were also made from liver, tonsil, colon, and ileum. On the basis of the prevalence data, the economic significance of paratuberculosis to the New England dairy industry was estimated in excess of +15.4 million annually. Field studies identified 25 infected herds in New England. One of the infected herds from Connecticut was sold at public auction, an act which resulted in the dissemination of 95 potentially infected cattle to 28 farms in 8 different states.  相似文献   

7.
Responses of Beijing black hogs to porcine somatotropin   总被引：2，自引：0，他引：2  
Somatotropin treatment of U.S-breed finishing hogs improves feed efficiency, growth rate and carcass lean-to-fat ratio. Because Chinese-bred hogs have poorer feed efficiency, growth rate and lean-to-fat ratio than U.S. bred hogs, the characteristics affected by porcine somatotropin (PST) may respond differently to treatment. In the present experiment, Beijing Black finishing hogs (a composite of a local Chinese, Berkshire and Yorkshire breeds) were treated with PST for 28 d from average initial to final weights of 67.8 to 96.6 kg. In hogs individually fed as much as they would eat four times a day (n = 12/treatment group, six gilts and six barrows), feed efficiency was improved by 22.4 and 29.9% by 2 and 4 mg/d PST, respectively (P less than .01), primarily due to increased growth rate (22.1 and 32.6% greater than control, respectively, P less than .01); feed intake was not affected. Performance of group-housed and group-fed hogs (six/pen, four pens/treatment) administered 2 mg/d PST for 28 d (average initial and final weights of 66.5 +/- 1.7 and 94.0 +/- 2.4 kg, respectively) was similar (22.7% improved feed efficiency, P less than .01; 25% increased growth rate, P less than .01). At slaughter, last rib backfat thickness was decreased an average of 19.2% for hogs treated with 2 and 4 mg/d PST (P less than .01). Percentage of total muscle, obtained by physical separation of the half-carcass, was increased an average of 13.5% (P less than .01), whereas percentage of total fat was decreased 21.8% (P less than .01) in PST-treated hogs. The pH, water-holding capacity and meat color scores of longissimus muscle from PST-treated hogs did not differ from those of control hogs. Growth rate, feed efficiency and muscle weight responses to PST treatment were at least as large as those for U.S. breeds.  相似文献   

8.
Groups of hog sera from endemic and non-endemic areas for swine trichinellosis in Yugoslavia were tested by ELISA using excretory-secretory (ES) antigens collected from T. spiralis muscle larvae maintained in vitro for 24, 48 or 72 h. The 24-h ES had the highest level of specificity for T. spiralis infection. Antigen preparations recovered after 48 or 72 h yielded an increasing rate of false-positive reactions. Additional antigens occurred in the 48- and 72-h ES preparations as determined by gel electrophoresis and monoclonal antibody binding. The occurrence of false-negative reactions was directly correlated with T. spiralis worm burdens. Hogs with muscle larvae densities greater than 10 larvae per gram were all positive by ELISA. Among 17 hogs with less than 10 larvae per gram, only one hog was negative by ELISA with 24-h ES antigen; the false-negative rate was higher with 48- and 72-h ES. These results show that ES antigen produced during the first 24 h of in vitro cultivation is highly specific for the immunodiagnosis of swine trichinellosis.  相似文献   

9.
Salmonella in the mesenteric lymph nodes of healthy sows and hogs   总被引：1，自引：0，他引：1  
Mesenteric lymph nodes were collected from healthy sow and slaughter hogs that had been kept in holding pens for an average of 10 and 2 days, respectively, before slaughter at an abattoir. Salmonella was isolated from 58.2% (67/115) of the sows and 31.3% (16/51) of the slaughter hogs. This difference in Salmonella prevalence was significant (chi 2 = 10.22, P less than 0.005); therefore, the hypothesis that there would be no significant difference in the infection rates of sows and slaughter hogs was rejected.  相似文献   

10.
An excretory-secretory (ES) antigen was used in a serodiagnostic enzyme-linke immunosorbent assay (ELISA) for swine trichinosis. ELISA procedures included a double- antibody test, using either an anti-swine IgG or a protein A enzyme conjugate, and a triple-antibody test using a pig IgG heavy-chain specific second antibody with a conjugated third antibody. The ES antigen was effective in eliminating all false-positive reactivity in sera from farm-raised hogs. The triple-antibody procedure was more sensitive and demonstrated a greater efficiency in detecting positive animals and early seroconversions. Naturally-infected pigs with worm burdens as low as 0.01 larvae per gram (LPG) of diaphragm were seropositive using these procedures. Seroconversion in experimentally-infected animals receiving low doses of muscle larvae (500) occurred considerably later than in animals receiving high doses (10000). This might account for false-negative reactions in naturally-infected animals with very low (less than 0.1 LPG) worm burdens.  相似文献   

11.
用10％甲醛已固定17个月的痒病绵羊脑干组织悬浮液，人工接种于2只新西兰边区莱斯特育成羊（2＃、11＃）及2只新西兰边区莱斯特和美利奴杂交2代的育成羊（3286＃、3150＃）的脑内，观察293d。结果显示，11＃新西兰边区莱斯特羊发病后剖杀，组织学检查发现其延脑内出现大的特异性空泡变性的神经元，证明痒病因子对甲醛有较强的抵抗力。  相似文献   

12.
Rabbits of the New Zealand White and Small Chinchilla breeds were each infected at 3-4 months of age with 4-10 thousand invasive trichostrongyle larvae. Prepatent period of the infection was 22-32 days. Third-stage larvae were present up to the 6th day of infection, fourth-stage from the 8th day, fifth-stage from the 14th day and sexually mature trichostrongyles on the 18th day. The period of patency of the infection lasted for over a year, but only small numbers of eggs were passed in faeces, and food intake was not affected. Between 14 and 44% of the third-stage larvae developed into sexually mature nematodes, regardless of infection dose or duration of infection.  相似文献   

13.
Faecal specimens from 200 market swine (115 feeder pigs and 85 butcher hogs) offered for sale at a southern California livestock auction yard during a three-month period, were examined for cryptosporidium oocysts. Of the 10 pigs (5 per cent) found to be excreting the parasite, seven were feeder pigs and three were butcher hogs. Of the feeder pigs four (4.1 per cent) came from the 98 non-diarrhoeic pigs and three (17.6 per cent) from 17 diarrhoeic pigs. The 85 butcher hogs were all apparently healthy.  相似文献   

14.
In March 1973, a modified live virus vaccine was released for sale in the United States for the protection of neonatal calves from infection with calf rotavirus. At that time no published evidence existed that this agent was present in New York or the New England states. Serum neutralizing antibodies for the calf rotavirus (reovirus-like agent of neonatal calf diarrhea) were detected in serum from 108 of 110 dairy cattle in New York State representing 78 different herds. To exclude the possibility that the demonstrated serologic response may have been stimulated by vaccine virus, 36 samples were included that had been collected prior to the date of vaccine release. Neutralizing antibodies were demonstrated in 108 of the 110 sera ranging from titers of 4 to greater than 1024, thereby offering indirect evidence of the ubiquitous nature of calf rotavirus in New York.  相似文献   

15.
Effect of atrophic rhinitis on growth rate in Illinois swine herds   总被引：4，自引：0，他引：4  
Influence of atrophic rhinitis (AR) on mean daily weight gain (MDG) was studied in hogs randomly selected from 7 farrow-to-finish herds in Illinois. Herds were selected to obtain a wide range of clinical signs and lesions of the disease; thus, prevalence of clinical signs of AR in finishing hogs ranged from 0% to 20% among herds, and in hogs examined at slaughter the proportion of hogs with turbinate lesions ranged from 5% to 92%. None of the herds investigated had any obvious problems with pneumonia; nevertheless, hogs with moderate to severe pneumonic lesions were excluded from the study, to minimize any combined effect of AR and pneumonia. In 3 herds, MDG in AR-free pigs was 15% to 18% better than in pigs with severe AR lesions. Prevalence of clinical signs ranged from 5% to 20%, and of turbinate lesions, from 66% to 92%. In 4 herds in which MDG appeared to be unaffected by AR, prevalence of clinical signs of the disease ranged from 0% to 5%, and of turbinate lesions, from 5% to 74%. No consistent pattern of influence on AR lesions was found for bacterial infections, as determined by culturing of nasal swab specimens on MacConkey agar and blood agar.  相似文献   

16.
Two anthelmintics, fenbendazole and cambendazole, were used in an attempt to eliminate Muellerius capillaris infections in a group of 44 goats. During the course of this study (508 days), M capillaris larvae were found in at least one fecal specimen from each of 22 of the 44 goats. All 44 goats were dewormed with fenbendazole (30 mg/kg of body weight) at the onset of this study (day 18). Two additional dewormings with fenbendazole at 4- to 8-week intervals were restricted to the goats that continued to shed M capillaris larvae. On the basis of routine fecal examinations, fenbendazole eliminated M capillaris larvae from the feces of 8 (36%) of these 22 goats. On day 253, cambendazole (60 mg/kg) was given orally to 17 of these 22 goats (2 of the 22 had died and 3 were not available for treatment); 13 of these goats were still shedding M capillaris larvae. Cambendazole eliminated M capillaris larvae from the feces of 10 (77%) of these 13 goats chronically infected with M capillaris.  相似文献   

17.
A survey of anteroventral (AV) lung lesions, pleuritis and serology for Mycoplasma hyopneumoniae (MH) and Actinobacillus pleuropneumoniae (AP) was conducted on a minimum of 25 slaughter hogs from each of 18 randomly sampled Prince Edward Island farms (producing over 1,000 market hogs per year). The data were analyzed to evaluate the potential role of these two agents as risk factors for the two conditions, using crude and multivariable techniques, as well as individual and herd data. Anteroventral lung lesions were present in 50.5% of hogs at slaughter, and pleuritis was present in 15.4% of the hogs. Least squares multivariable regression was used to analyze the simultaneous ability of MH, AP and MH/AP interaction to predict the herd prevalence of AV lung lesions. Only MH was associated with AV lung lesions (p = 0.035). In spite of this statistical significance, MH accounted for only 53% of the herd variation in prevalence of lung lesions (R2 = 0.529). As well, some herds maintained very low levels of lung lesions despite moderate (up to 30%) prevalence of MH. Discrepancies between the analytic techniques suggested herd-level factors play an important role in the development of lung lesions. Pleuritis did not appear to be associated with either of the agents studied (p = 0.478).  相似文献   

18.
The US swine industry is large and growing. The quantity of pork desired by consumers of US pork is growing at the rate of 1.5%/y. New production systems and new technology have enabled production per sow to grow at a rate of 4% annually in recent years. Consequently, the number of sows in the United States is declining. Because productivity growth is outpacing demand growth, the deflated price of hogs and pork is declining. Hog production and prices continue to exhibit strong seasonal and cyclic patterns. Pork production is usually lowest in the summer and highest in the fall. Production and prices tend to follow 4-year patterns. The US swine industry continues to evolve toward fewer and larger producers who rely on contracts for both hog production and marketing. In 2000, over half of the hogs marketed were from approximately 156 firms marketing more than 50,000 head annually. These producers finished 60% of their production in contract facilities. Over 90% of their marketings were under contract or were owned by a packer. These producers expressed a high level of satisfaction with hog production. Both they and their contract growers were satisfied with production contracts. These large producers were satisfied with their marketing contracts and planned to continue them in the future. The hog industry has changed a great deal in the last decade. There is little reason to believe this rapid rate of change will not continue. This swine industry is highly competitive and profit driven. Profit margins are too small to allow producers the luxury of ignoring new technology and innovative production systems. Consequently, hog production will continue its rapid evolution from traditional agriculture to typical industry.  相似文献   

19.
Trichinella nativa in a black bear from Plymouth, New Hampshire   总被引：1，自引：0，他引：1  
A suspected case of trichinellosis was identified in a single patient by the New Hampshire Public Health Laboratories in Concord, NH. The patient was thought to have become infected by consumption of muscle larvae (ML) in undercooked meat from a black bear killed in Plymouth, NH in October 2003 and stored frozen at -20 degrees C fro 4 months. In January 2004, a 600 g sample of the meat was thawed at 4 degrees C, digested in hydrochloric acid and pepsin, and larvae were collected by sedimentation. Intact, coiled, and motile ML were recovered (366 larvae per gram (l pg) of tissue), which were passed into mice and pigs. Multiplex PCR revealed a single 127 bp amplicon, indicative of Trichinella nativa. The Reproductive Capacity Index (RCI) for the T. nativa-Plymouth isolate in mice was 24.3. Worm burdens in the diaphragms of two 3-month-old pigs given 2,500 ML were 0.05 and 0.2l pg by 35 days post-inoculation, while 2.2 and 0.75 l pg were recovered from two 3-month-old pigs given 10,000 ML; no larvae were recovered from four 1-year-old pigs given 2,500 ML (n=2) or 10,000 ML (n=2). Viable larvae were also recovered from frozen black bear meat harvested at two additional locations, one in southern Ontario, Canada, and one in upstate New York, USA. Multiplex PCR using genomic DNA from these parasite samples demonstrated that both isolates were T. nativa. This is the first report of the freeze-resistant species, T. nativa, within the continental United States.  相似文献   

20.
Three slaughter checks were performed for each of 21 swine producers at 6-month intervals. Two slaughter checks were performed during the winter, and 1 slaughter check was performed during the summer. Lesions of atrophic rhinitis and pneumonia were evaluated during the slaughter checks. Two types of farrowing facilities and 4 types of grower/finisher facilities were used by the swine producers. Lesions of atrophic rhinitis and pneumonia were compared among seasons and among types of facilities. Lesions of both atrophic rhinitis and pneumonia varied with season. Lesions of atrophic rhinitis were more severe among hogs slaughtered in the summer, whereas lesions of pneumonia were more severe among hogs slaughtered in the winter. Lesions of atrophic rhinitis were more severe in hogs farrowed in central, enclosed farrowing houses and finished in enclosed, mechanically ventilated buildings than in hogs farrowed individually in sow huts and finished on dirt lots. Knowledge of disease patterns associated with season and facilities is useful for assessment of herd health status and for implementation of control programs.  相似文献   

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