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1.
The prevalence and distribution of seropositivity towards the protozoan parasite Neospora caninum were studied in single blood samples from 1561 cows from 31 Danish dairy herds. Blood samples were analysed by an indirect enzyme-linked immunoassay and an indirect fluorescent-antibody test. Seroprevalence in 15 herds with previous abortions assigned to neosporosis ranged from 1% to 58%, with a mean frequency of 22%. In eight out of 16 herds without a history of N. caninum related abortions, no seroreactors were found. In the remaining eight herds, the seroprevalence ranged from 6% to 59%. The prevalence and distribution of seropositivity, gestation number prior to sampling, and breed were related to abortions and perinatal deaths using a random-effects logistic-regression model. Abortion risk was significantly increased in seropositive animals (OR=3) and in 2nd-gestation cows (OR=3). Perinatal death was significantly influenced by gestation number and breed, but not by serostatus. Reproductive performance and culling risk of cows were not affected by serostatus. Seropositivity increased with “age” (i.e. gestation number) (P=0.02). In open cows, seropositivity tended to decrease with distance from calving (P=0.05). The proportion of seropositive pregnant cows increased with trimester (P=0.02).  相似文献   

2.
The prevalence and distribution of seropositivity towards the protozoan parasite Neospora caninum were studied in single blood samples from 1561 cows from 31 Danish dairy herds. Blood samples were analysed by an indirect enzyme-linked immunoassay and an indirect fluorescent-antibody test. Seroprevalence in 15 herds with previous abortions assigned to neosporosis ranged from 1% to 58%, with a mean frequency of 22%. In eight out of 16 herds without a history of N. caninum related abortions, no seroreactors were found. In the remaining eight herds, the seroprevalence ranged from 6% to 59%. The prevalence and distribution of seropositivity, gestation number prior to sampling, and breed were related to abortions and perinatal deaths using a random-effects logistic-regression model. Abortion risk was significantly increased in seropositive animals (OR=3) and in 2nd-gestation cows (OR=3). Perinatal death was significantly influenced by gestation number and breed, but not by serostatus. Reproductive performance and culling risk of cows were not affected by serostatus. Seropositivity increased with “age” (i.e. gestation number) (P=0.02). In open cows, seropositivity tended to decrease with distance from calving (P=0.05). The proportion of seropositive pregnant cows increased with trimester (P=0.02).  相似文献   

3.
AIM: To estimate the distribution and causes of abortion in dairy herds across New Zealand during the 2001/2002 breeding season.

METHODS: A questionnaire survey was sent to all veterinary practices that employed members of the New Zealand Veterinary Association. Veterinarians were requested to record the numbers of dairy herds serviced by their practice in which the rate of aborting cows was zero (0%), low (1–5%) and high (6–10% and >10%), and all laboratory submissions, specimens, tests and results related to their investigation of abortions in these herds, for each category.

RESULTS: Forty-two large animal practices serving 1,431 dairy clients from all except one region in New Zealand responded. The within-herd incidence of abortion was zero in 497 herds (34.7%), low in 876 herds (61.2%), and high in 58 herds (4.1%) in the season 2001/2002. Within the high category, 0.6% herds reported abortions at a frequency as high as may be expected in epidemic abortions (>10%). Compared to other regions, the abortion incidences tended to be relatively high in Northland, Auckland and the Bay of Plenty, and low in Hawke Bay, Waikato and Nelson (p<0.001). Cases were submitted for laboratory investigation from 51/934 (5.5%) herds. Even though submission rates increased with the level of abortion, most submissions originated from herds with a low abortion rate. The main agents identified among submissions as the cause of abortion were Neospora caninum (Nc) (35%) and bovine viral diarrhoea virus (BVDV) (16%). Among 39 submissions from low abortion herds, 33% were suspected due to Nc and 15% to BVDV, and this was not statistically different (p>0.10) from the distribution in 13 submissions from high abortion herds (46% Nc, 23% BVDV). While cases associated with Nc were submitted in April, May and June, submissions for suspected BVDV spread evenly over the months of March to July.

CONCLUSION: In the 2001/2002 season, approximately 4% of dairy herds in New Zealand recorded a relatively high incidence of abortion (>5%) and 0.6% herds experienced an incidence of >10%. BVDV and Nc were the most frequently diagnosed agents associated with abortion, regardless of whether the seasonal incidence of abortion within a herd was low or high.  相似文献   

4.
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5.
Epidemiology of bovine abortions in Israeli dairy herds   总被引：1，自引：0，他引：1  
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6.
A serological survey for antibodies against Neospora caninum in aborting cattle was carried out in the Czech Republic. Serum samples from 463 aborting dairy cows originated from 137 farms from different parts of the Czech Republic were tested for presence of N. caninum antibodies by use of an enzyme-linked immunosorbent assay (ELISA) and an indirect fluorescent antibody test (IFAT). Antibodies (> or = 1:640) to N. caninum were found in 18 (3.9%) of 463 aborting cows. Farm prevalence in aborting cows was 12.4% (17/137). The antibody titres of cows were 1:200 (9 cows), 1:640 (7 cows), 1:1280 (3 cows), 1:2560 (3 cows), 1:5120 (3 cows), 1:10,240 (2 cows) and 1:20,480 (0 cow). A case-control study was conducted to estimate the association of N. caninum infection and abortion. For this 407 serum samples were collected from cows on five dairy farms with repeated occurrence of endemic and sporadic abortion of unidentified etiology. These samples were obtained from aborting cattle (n=44) and normally calving cattle (control group; n=363) and tested for N. caninum antibodies by an immunofluorescent antibody test (IFAT). Overall, 3.19% (13/407) of cows sampled had positive N. caninum fluorescence with a cut-off titre of 1:200. The prevalence of N. caninum was significantly higher (P<0.05) in the aborting group (13.64%; 95% confidence interval (CI): 5.2, 27.4) than in the control group (1.93%; 95% CI: 0.8, 3.9). A strong association between seropositivity and abortion was found, with seropositive cows being eight times more likely to abort than seronegative cows (odds ratio=8; 95% CI: 2.6, 25.1). This first report on the serological prevalence of N. caninum in cows in the Czech Republic verified a strong association between N. caninum infection and abortions in five dairy farms. Thus, the neosporosis should be considered in differential diagnosis of bovine abortion.  相似文献   

7.
A seroepidemiological survey of Neospora caninum and Toxoplasma gondii in cattle and water buffaloes was carried out in the People's Republic of China. Serum samples were obtained from dairy (n=262, 9 herds in 9 provinces) and beef cattle (n=10, 1 herd) and water buffaloes (n=40) in China. All sera were tested for antibodies to N. caninum and T. gondii by an enzyme-linked immunosorbent assay (ELISA) and an indirect agglutination test (IAT), respectively. The overall seroprevalence of N. caninum in dairy cattle was 17.2% (45/262), and the herds seroprevalence of N. caninum was 88.9% (8/9), and antibodies to T. gondii were present in 6 cows (2.3%). None of the cows had antibodies against both T. gondii and N. caninum. Antibodies to T. gondii or N. caninum were not found in beef cattle or water buffaloes. The seroprevalence of N. caninum in aborting cows (20.2%) was higher than that in non-aborting cows (16.6%) with an odds ratio of 1.26 (95% CI, 0.54-2.95), but the difference was not statistically significant (P>0.05). There was no apparent association of N. caninum seropositivity with age or number of pregnancies. This is the first report on the seroprevalence of N. caninum in cattle and water buffaloes in China.  相似文献   

8.
The seroprevalence of Neospora caninum infection was estimated from a sample of 889 cattle from 43 dairy herds in three counties in the Asturias region of Spain. The true prevalence of infection was estimated to be 30.6 per cent (95 per cent confidence interval (CI) 27.6 to 33.6). Seropositivity was associated with abortion during the previous year (odds ratio (OR)=3.31, P<0.001) and was slightly higher among purchased cattle (37.6 per cent), than among cattle raised on the farm (29.1 per cent) (P=0.078). Seropositive cows were more likely than seronegative cows to have had a seropositive dam (OR=2.3, P=0.011), suggesting that congenital transmission contributed to about 56 per cent of the infections. Herds with a true seroprevalence above 10 per cent had more dogs on the farm, than herds with a lower prevalence (P=0.032). The ORS relating abortion to seropositivity in individual herds ranged from 0.7 to 19, indicating that some herds experienced few abortions caused by N. caninum, while others experienced more abortions due to the organism. Overall, 38.7 per cent of the abortions were estimated to have been attributable to N. caninum.  相似文献   

9.
Data derived from 340 dairy herds, mainly in southern England, between April 1998 and March 1999, showed that the average total culling rate was 22.1 per cent, with 5.6 per cent for infertility, 3.6 per cent for mastitis, 1.7 per cent for lameness, 2.0 per cent for poor milk yield, 3.7 per cent for age and 5.5 per cent for miscellaneous reasons which included death. The average annual rate of assisted calvings was 8.7 per cent, of injury 0.9 per cent, digestive disease 1.3 per cent ketosis 0.4 per cent, hypomagnesaemia 0.7 per cent, hypocalcaemia 5.3 per cent, mastitis 36.6 per cent, and lameness 23.7 per cent. There was a significant association (P<0.001) between higher rates of mastitis in cows housed in straw yards as opposed to cubicles and also between higher rates of lameness in cows housed in cubicles as opposed to yards (P<0.015). However, there were farms with low rates of mastitis in cows kept in straw yards and low rates of lameness in cows kept in cubicles. Larger herds tended to have more problems with lameness and higher bulk milk somatic cell counts (BMSCC). There was a positive association between BMSCC and mastitis rate.  相似文献   

10.
A study was carried out to investigate the effect of restricting silage feeding on time of calving and calving performance in Holstein-Friesian cows. In the treatment group (n = 1,248 cows, 12 herds) silage feeding commenced in the evening (17:00 to 20:00 h), after a period of restricted access (2 to 10 h) while in the control group ad-libitum access to silage was provided over the 24 h period (n = 1,193 cows, 12 herds). Daytime and nighttime calvings were defined as calvings occurring between the hours of 06:30 and 00:29 and between 00:30 and 06:29, respectively. Restricting access to silage resulted in less calvings at night compared to cows with ad-libitum access to silage (18 vs 22%, P < 0.05). Cows with restricted access to silage had a higher percentage of difficult calvings (11 vs 7%, P < 0.001) and stillbirths (7 vs 5%, P < 0.05) compared to cows in the control group. The percentage of calvings at night was lower (13%) when access to silage was restricted for 10 h compared to 2, 4 or 6 h (22, 18, 25%, respectively) (P < 0.001). Calf sire breed, calf gender or cow parity did not influence time of calving. In conclusion, offering silage to pregnant Holstein-Friesian cows in the evening, after a period of restricted access, reduced the incidence of nighttime calvings, but increased the incidence of dystocia and stillbirth.  相似文献   

11.
The factors affecting the mortality of cows in Danish dairy herds were investigated by analysing data from 6839 herds. The mean risk of mortality during the first 100 days of lactation was 2.5 per cent. The risk of mortality increased with increasing herd size (odds ratio [OR] 1.05 for an increase in herd size of 50 cows), with the proportion of purchased cows (OR 1.05 for an increase in the proportion of purchased cows of 0.1), and with increases in the somatic cell count (OR 1.16 for an increase in average weighted mean somatic cell count of 100,000 cells/ml). The risk decreased with increasing average milk yield per cow (OR 0.93 for an increase in mean yield per cow-year of 1000 kg). The risk was lower in free-stall barns with deep litter (OR 0.79) than in barns with cubicles (OR 1) or tie-stalls (OR 1.04). Herds with Danish Holstein (OR 1) or Danish Jersey (OR 0.93) cows as the predominant breed had a higher risk of mortality than herds of the Danish red dairy breed (OR 0.67). The risk of mortality was lower in organic herds (OR 1) than in conventional herds (OR 1.17), and lower in herds that grazed pasture during the summer (OR 0.78).  相似文献   

12.
An epidemiologic study of ketosis in dairy cows in Sweden covering approximately 125 000 calvings in 1268 herds is presented and various risk factors identified.The Swedish Red and White breed (SRB) had a higher incidence of ketosis than the Swedish Friesian breed (SLB). A positive report of parturient paresis, alone or in combination with a positive report of retained placenta increased the risk of ketosis in SRB cows. Simultaneous reports of parturient paresis and retained placenta increased the risk of ketosis in SLB cows. Tied cows of both breeds with pasture had a decreased risk during the months of pasture. The incidence of ketosis decreased with herd size, and tied zero-grazing cows had a higher incidence than loose-housed cows.Cows reported positive once for ketosis had an increased risk in subsequent calvings but no increased risk of removal during lactation.  相似文献   

13.
A comprehensive database was established on the milk production and reproductive performance of dairy cows in 19 selected herds in Northern Ireland, varying in size, management system and genetic merit. Data were obtained for 2471 cows, 1775 of which calved in a second year, and 693 were culled from the herd for specific reasons. The estimated mean rate of heat detection (assessed by the interheat interval during the main breeding season) in all the herds was 71 per cent, with a range from 53 to 92 per cent The average conception rate to first insemination was 37.1 per cent (range 21 to 66 per cent). The average calving interval for the retained cows was 407.2 days (range 359 to 448 days). Twenty-eight per cent of the cows that calved were culled, with infertility being the largest single reason (26.8 per cent of the cows culled). There were major differences in reproductive performance between the herds, but heat detection rate, conception rate and calving interval did not appear to be affeded by a herd's genetic merit. The herds with shorter calving intervals were characterised by better heat detection efficiency (83 v 61 per cent, P<0.01), a shorter interval from calving to first insemination (74 v 97 days; P<0.05), a higher conception rate to first insemination (45 v 34 per cent, P>0.10) and a lower removal rate (23 v 37 per cent, P<0.01). Furthermore, the cows in these herds had lower body condition scores (BCS) in the dry period (3.0 v 3.3; P<0.05) but lost less body condition in early lactation (0.3 v 0.6 BCS units, P<0.05). These results show that dairy herd fertility in Northern Ireland is generally low and similar to that previously reported for England and the USA, but that in some herds changes in herd management practices improved the cows' fertility.  相似文献   

14.
The mandatory reporting and investigation of bovine abortions provides a system for the surveillance of the progress of the Brucellosis Eradication Scheme and a warning of resurgence of brucellosis in tested herds. Before the scheme was introduced in 1971, about a quarter of all abortions were caused by Brucella abortus. By 1976, the percentage of abortions due to Brucella in herds under test for brucellosis had been reduced to 3.4%. Most Brucella abortions occurred during the seventh and eighth months of gestation. Cows in the 4- to 6-year-old age group were at greater risk of aborting from Brucella infection than heifers. Approximately 94% of all aborting cows were in herds which experienced three or fewer abortions. Less than 4% of herds experienced four or more abortions annually. In most cases of abortion due to brucellosis, more than one diagnostic test yielded positive results. However, 13.3% of cases were recognised by positive bacteriological results alone.  相似文献   

15.
The effect of summer grazing in large Danish dairy herds and certain management characteristics of grazing were studied for their impact on dairy cow mortality. Mortality data (from the Danish Cattle Database) from 391 Danish dairy herds (>100 cows) were combined with information from a questionnaire survey of grazing procedures on these herds in 2008. In all, 131 of the herds were identified as summer grazing and 260 as zero-grazing herds. The mortality was affected by an interaction of summer grazing and milking system. The risk of a cow dying was reduced to 46% in a grazing compared to a zero-grazing herd having automatic milking system. In traditional milking system, mortality was reduced to 75% in grazing compared to zero-grazing herds. Within the grazing herds, the risk of mortality decreased with increasing number of hours on pasture during the season. Free access between barn and pasture was associated with increased cow mortality.  相似文献   

16.
A cross-sectional questionnaire survey was performed on dairy herds in Flanders (Belgium) to detect management factors that are associated with an increased gastrointestinal parasite infection level of adult dairy cows. At the end of the grazing season, information concerning general herd factors, pasture management and anthelmintic treatment strategy was obtained from 956 herds. A bulk tank milk sample was obtained from 779 out of the 956 herds and the antibody levels (ODR) against Ostertagia ostertagi were determined. The associations between ODR and herd management factors were studied by two linear regression models. The first model evaluated the effect of general herd factors and the level of the cows' exposure to pasture. Large sized herds had significantly lower ODRs as compared to medium (P=0.001) or small sized herds (P=0.03). Herds with only dairy cows had lower ODRs than herds with both dairy and beef cows (P=0.02). An increased exposure to pasture of the cows was associated with higher ODRs (P<0.001). The second model was built to evaluate the effect of pasture management factors and anthelmintic treatment strategy. Later turn-out on pasture (P<0.001) and mowing (P=0.002) were both significantly associated with lower ODRs. Cows that had a restricted grazing time per day tended to have lower ODR than cows that grazed 24 h per day (P=0.07). An increased exposure to pasture of the heifers was significantly associated with higher ODRs (P=0.001). No associations were found between ODR and calf related management factors, anthelmintic treatment strategy, time of turn-in, rotational grazing type or stocking rate. Later turn-out on pasture, mowing and restricting the grazing time per day are factors that can be applied immediately on dairy farms to reduce economical losses due to gastrointestinal nematodes.  相似文献   

17.
Paratuberculosis is a chronic infection affecting cattle and other ruminants. In the dairy industry, losses due to paratuberculosis can be substantial in infected herds and several countries have implemented national programmes based on herd-classification to manage the disease. The aim of this study was to develop a method to estimate the probability of low within-herd prevalence of paratuberculosis for Danish dairy herds. A stochastic simulation model was developed using the R® programming environment. Features of this model included: use of age-specific estimates of test-sensitivity and specificity; use of a distribution of observed values (rather than a fixed, low value) for design prevalence; and estimates of the probability of low prevalence (PrLow) based on a specific number of test-positive animals, rather than for a result less than or equal to a specified cut-point number of reactors.

Using this model, five herd-testing strategies were evaluated: (1) milk-ELISA on all lactating cows; (2) milk-ELISA on lactating cows ≤4 years old; (3) milk-ELISA on lactating cows >4 years old; (4) faecal culture on all lactating cows; and (5) milk-ELISA plus faecal culture in series on all lactating cows.

The five testing strategies were evaluated using observed milk-ELISA results from 19 Danish dairy herds as well as for simulated results from the same herds assuming that they were uninfected.

Whole-herd milk-ELISA was the preferred strategy, and considered the most cost-effective strategy of the five alternatives. The five strategies were all efficient in detecting infection, i.e. estimating a low PrLow in infected herds, however, PrLow estimates for milk-ELISA on age-cohorts were too low in simulated uninfected herds and the strategies involving faecal culture were too expensive to be of practical interest. For simulated uninfected herds, whole-herd milk-ELISA resulted in median PrLow values >0.9 for most herds, depending on herd size and age-structure. None of the strategies provided enough power to establish a high PrLow in smaller herds, or herds with a younger age-structure. Despite this, it appears as if the method is a useful approach for herd-classification for most herds in the Danish dairy industry.  相似文献   


18.
Investigations of 1167 dairy cows out of 105 herds with fertility disorders on secretion of Coxiella burnetii (C. burnetii) by the genitals as well as serological studies of these animals using ELISA demonstrated that C. burnetii infections are significantly associated with abortions but not with repeated inseminations without success or vaginal excretions. The demonstration of an increased risk of infections for persons caring for those dairy herds could be shown by a total of 253 serological studies. A comparison of these studies of farmers caring for dairy herds suffering from abortions a seroprevalence of > or = 20% showed that these persons revealed significantly more frequent antibodies against C. burnetii than farmers of the group compared with. Further studies showed that in herds suffering from abortions a seroprevalence of > or = 20% means an additional risk of infections of farmers. Vice versa abortions of the cows in herds with a seroprevalence of > or = 20% imply an additional infectious risk.  相似文献   

19.
The protozoan parasite Neospora caninum and bovine virus diarrhoea virus (BVDV) are recognized as important causes of bovine abortion and congenital disease worldwide. In this study, serological investigations were performed to estimate the prevalence of N. caninum infection in Swedish dairy cattle, to assess to what extent it may affect abortion rates, and to determine possible effects of coinfection with BVDV. The overall N. caninum seroprevalence in Swedish dairy cows was estimated at 2% (16/780), and the BVDV seroprevalence was 32% (249/780). Among aborting cows from herds with abortion problems, 7% (26/378) had antibodies to N. caninum and 42% (153/378) to BVDV. Seventeen of the N. caninum positive animals also had antibodies to BVDV. There was a statistically significant (P = 0.013) association between presence of antibodies to N. caninum and BVDV. In a case-control study comprising sera from cows in herds without recognized abortion problems, 6% (5/89) and 1% (1/89) of sera from aborting and non-aborting cows, respectively, had antibodies to N. caninum. Two of the N. caninum seropositive aborting cows also had antibodies to BVDV. These results confirm that N. caninum infection is associated with bovine abortion in Sweden and also indicate that there might be concurrent effects of N. caninum and BVDV. It is concluded that Swedish dairy cows have a low prevalence of N. caninum infection which is favourable in relation to possible future control programmes.  相似文献   

20.
OBJECTIVE: To estimate seroprevalence of Mycobacterium avium subsp paratuberculosis (MAP) infection among adult dairy cows in Colorado and determine herd-level factors associated with the risk that individual cows would be seropositive. DESIGN: Cross-sectional observational study. ANIMALS: 10,280 adult (> or = 2 years old) dairy cows in 15 herds in Colorado. PROCEDURE: Serum samples were tested with a commercial ELISA. A herd was considered to be infected with MAP if results of mycobacterial culture of > or = 1 individual cow fecal sample were positive or if > or = 1 culled cow had histologic evidence of MAP infection. RESULTS: 424 of the 10,280 (4.12%) cows were seropositive. Within-herd prevalence of seropositive cows ranged from 0% to 7.82% (mean, 2.6%). Infection was confirmed in 11 dairies. Cows in herds that had imported > or = 8% of their current herd size annually during the preceding 5 years were 3.28 times as likely to be seropositive as were cows in herds that imported < 8%. Cows in herds with > or = 600 lactating cows were 3.12 times as likely to be seropositive as were cows in herds with < 600 lactating cows. Cows in herds with a history of clinical signs of MAP infection were 2.27 times as likely to be seropositive as were cows in herds without clinical signs. CONCLUSIONS AND CLINICAL RELEVANCE: Annual importation rate, herd size, and whether cows in the herd had clinical signs typical of MAP infection were associated with the risk that individual cows would be seropositive for MAP infection.  相似文献   

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