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1.
The aim of this study was to determine if the factors affecting the abortion rate in dairy herds with high incidence of Neospora‐associated abortions are different in pregnancies of cows and heifers chronically infected with Neospora caninum. In heifers (n = 229), an increase in the cumulative number of days with a mean relative humidity (RH) lower than 60% during the second trimester of gestation increases the risk of abortion. Yet, the likelihood of abortion was 7.6 times lower for pregnant heifers inseminated with Limousin bull semen, compared with those inseminated with Holstein‐Friesian bull semen. In pregnancies of parous cows (n = 521), an increase in rainfall and in the cumulative number of days with a mean RH lower than 60% during the second trimester of gestation increased the abortion rate. However, in contrast, an increase in the lactation number produced a decrease in the abortion rate, with a likelihood of abortion 4.8 times lower for pregnant cows inseminated with Limousin bull semen, and three times lower for those inseminated with Belgian Blue bull semen, compared with dairy cows inseminated with Holstein‐Friesian bull semen. Finally, the likelihood of abortion was 3.2 times lower for pregnancies of parous cows with low antibody titres against N. caninum (6–30 units) as compared to those with high antibody titres (≥30 units), whereas in heifers this variable had no effect. The practical recommendations of the present study include the control of the cow environment during the second trimester of gestation, the priority of culling for parous cows with higher antibody titres against N. caninum and the insemination of Neospora‐seropositive cows with semen from the Limousin breed.  相似文献   

2.
There is an evidence that the epidemiology of neosporosis differs in dairy and beef cattle, such that beef cattle carry a lower risk of abortion. The aim of the present study was to establish whether artificial insemination using semen from beef bulls could reduce the risk of abortion in dairy cows seropositive for the Neospora caninum parasite. Our study was based on yearly serological screening for neosporosis and on the confirmation of Neospora infection in aborted fetuses in two high‐producing dairy herds with a mean 28% seroprevalence of N. caninum antibodies. The study population comprised of 273 pregnancies in seropositive animals: 156 pregnancies monitored after insemination using Holstein–Friesian semen and 117 after insemination using beef bull semen. Abortion rates for these animals were 28.2% (77 of 273), 34.6% (54 of 156) and 19.7% (23 of 117). Logistic regression analysis indicated no significant effects of lactation number and previous abortion on the abortion rate. Based on the odds ratio, a 1‐unit increase in the Neospora antibody titre yielded a 1.01‐fold increase in the abortion rate. The likelihood of abortion was two times higher for cows in one of the two herds and 2.8 times lower (one of 0.36) for pregnant cows inseminated with beef bull semen rather than Holstein–Friesian semen. Our results indicate that the use of beef bull semen can reduce the risk of abortion in dairy cows, and suggest that annual screening for neosporosis, specifically the antibody titre to the protozoan, could be an useful predictor of abortion risk in reproductive health programmes.  相似文献   

3.
Gamma interferon (IFN‐γ) production and cross‐breed pregnancy have been attributed a role in protecting dairy cows infected with Neospora caninum against abortion. Plasma levels of pregnancy‐associated glycoproteins‐1 (PAG‐1) are a marker of placental/foetal well‐being and of PAG‐2 is an abortion risk indicator in chronically N. caninum‐infected animals. The present study examines, in cross‐breed pregnancies, interactions between IFN‐γ production and levels of PAG‐1 and PAG‐2 in non‐aborting naturally Neospora‐infected dairy cows. Data were obtained from 60 pregnant Holstein‐Friesian cows: 44 Neospora‐seropositive and 16 Neospora‐seronegative; 12 became pregnant using Holstein‐Friesian semen and 48 using Limousin semen. Blood samples were collected on Days 40, 90, 120, 150, 180 and 210 of gestation. Gamma interferon was only detected in the plasma of nine of the 44 Neospora‐seropositive cows, all of them became pregnant using Limousin semen. Through GLM procedures, in cows inseminated with Limousin semen and Neospora‐seropositive cows showing no IFN‐γ production, PAG‐1 concentrations were high and increased throughout gestation compared to the levels detected in cows inseminated with Holstein‐Friesian semen and Neospora‐seropositive cows producing IFN‐γ, respectively. In Neospora‐seronegative cows and in Neospora‐seropositive cows showing no IFN‐γ production, significantly increased PAG‐2 concentrations were observed on gestation Day 120. Our findings indicate that IFN‐γ production correlates negatively and the production of antibodies against N. caninum is uncorrelated with plasma PAG concentrations during gestation in Neospora‐infected dairy cows. Accordingly, IFN‐γ production could be linked to the transplacental migration of tachyzoites, which may cause a reduction in PAG levels.  相似文献   

4.
The possible direct relationship between climate variations and abortion in Neospora caninum‐infected cows has not been studied. The objective of this study was to determine whether climate changes could be a risk factor for abortion in N. caninum‐infected cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection on aborted fetuses in two high‐producing dairy herds with a mean 27% seroprevalence of N. caninum antibodies. The final population study was comprised of 357 pregnancies in seropositive animals. Logistic regression analysis indicated no significant effects of herd, N. caninum antibody titre, climate variables during the first and third trimesters of gestation, mean and maximum temperature–humidity index values during the second trimester of gestation, and previous abortion on the abortion rate. Based on the odds ratio, a 1‐unit increase in lactation number yielded a 0.85‐fold decrease in the abortion rate. The likelihood of abortion was 1.9 times (1/0.54) lower for pregnant cows inseminated with beef bull semen compared with Holstein‐Friesian bull semen. The likelihood of abortion decreased significant and progressively by factors of 0.5, 0.41 and 0.3 for the respective classes 40–49, 30–39 and <30 rainfall mm during the second trimester of gestation (using the class ≥60 rainfall mm as reference). As a general conclusion, it seems that increased rainfall in a dry environment can compromise the success of gestation in N. caninum‐infected cows. Attempts should therefore be made to reduce environment effects during the second trimester of gestation, a period in which the immune response of cows is diminished.  相似文献   

5.
There is an evidence that the epidemiology of neosporosis differs in dairy and beef cattle, such that beef cattle carry a lower risk of abortion. The aim of the present study was to establish whether artificial insemination using semen from beef bulls could reduce the risk of abortion in dairy cows seropositive for the Neospora caninum parasite. Our study was based on yearly serological screening for neosporosis and on the confirmation of Neospora infection in aborted fetuses in two high-producing dairy herds with a mean 28% seroprevalence of N. caninum antibodies. The study population comprised of 273 pregnancies in seropositive animals: 156 pregnancies monitored after insemination using Holstein-Friesian semen and 117 after insemination using beef bull semen. Abortion rates for these animals were 28.2% (77 of 273), 34.6% (54 of 156) and 19.7% (23 of 117). Logistic regression analysis indicated no significant effects of lactation number and previous abortion on the abortion rate. Based on the odds ratio, a 1-unit increase in the Neospora antibody titre yielded a 1.01-fold increase in the abortion rate. The likelihood of abortion was two times higher for cows in one of the two herds and 2.8 times lower (one of 0.36) for pregnant cows inseminated with beef bull semen rather than Holstein-Friesian semen. Our results indicate that the use of beef bull semen can reduce the risk of abortion in dairy cows, and suggest that annual screening for neosporosis, specifically the antibody titre to the protozoan, could be an useful predictor of abortion risk in reproductive health programmes.  相似文献   

6.
This present study, was designed to establish whether Neospora caninum infection affects the fertility of high‐producing dairy cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection in aborted foetuses. Assessment was made of 7518 artificial inseminations (AI) (applied to parous cows) performed in three herds. Of these inseminations, 2540 (33.8%) resulted in pregnancy; 34% of which corresponded to seronegative cows (2226 of 6556 AI performed in seronegative cows) and 32.6% to seropositive animals (314 of 962). Abortion occurred in 97 (30.1%) of the 314 pregnancies recorded in dams seropositive for N. caninum, while only 93 (4.2%) of the 2226 pregnancies in seronegative animals ended in abortion. Logistic regression analysis indicated no significant effects of N. caninum antibody titre, days in milk and milk production at insemination on fertility. Factors found to affect fertility were herd, season of insemination, lactation and insemination number, semen‐providing bull and AI technician. Our results indicate that N. caninum infection does not affect the fertility of high‐producing dairy cows.  相似文献   

7.
The antigen-specific IgG subclass response may be a convenient indicator of the underlying nature of T helper cell regulation. The aim of the present study was to identify possible differences in Neospora caninum-specific total plasma IgG, IgG1 and IgG2 antibody levels in purebreed and crossbreed pregnancies throughout gestation in beef and dairy cattle chronically infected with N. caninum. Comparisons were also made between aborting and non-aborting dams. The population examined comprised 96 pregnant parous cows seropositive for N. caninum. Plasma antibodies were determined on Days 90, 120, 150, 180 and 210 of gestation or until abortion. Of the 96 pregnancies examined, 12 ended in abortion. None of the 14 Holstein-Friesian (HF) cows inseminated with HF semen (HF-HF group) aborted, whereas 6 (11.0%) of the 54 HF cows inseminated with Limousin semen (HF-L group) and 6 (21.4%) of the 28 Rubia Gallega (RG) beef cows inseminated with RG semen (RG-RG group) aborted. In the 84 non-aborting cows, a significant positive effect of gestation day was observed on total IgG, IgG1 and IgG2 antibodies levels (P<0.0001 for the three variables). In RG-RG cows, significantly higher levels of IgG (P=0.003; d.f.=2; F-value=6.41), IgG1 (P<0.001; d.f.=2; F-value=10.55) and IgG2 (P=0.004; d.f.=2; F-value=5.82) antibodies against N. caninum were recorded throughout gestation compared to the other groups, whereas the levels of these antibodies were significantly lower in HF-HF on Days 180 and 210 of gestation. In aborting cows, significantly lower IgG (P=0.001; d.f.=1; F-value=25.21) and IgG2 (P=0.001; d.f.=1; F-value=20.39) antibody levels were observed in the RG-RG cows compared to the HF-L cows, whereas no significant effect on IgG1 antibody levels was detected in the two groups with aborting animals (RG-RG and HF-L). Our findings indicate that humoral mechanisms against N. caninum infection and abortion differ in purebreed pregnancies and crossbreed pregnancies in beef/dairy cattle.  相似文献   

8.
The mating of small beef type bulls (Angus, Eringer) to reduce difficulties at first calvings is increasingly applied in Switzerland. In contrast to this, calf producers refuse to use large type beef bulls on their cows because of direct and indirect damages due to increased calving problems. It proved to be an attractive alternative to use specially selected dual purpose bulls tested for ease of calving and high growth rate but low dairy performance, so called M-bulls (Meat bulls), out of the regular AI testing programme for Braunvieh and Simmentals.From 1974 to 1976, Charolais, Limousin and Piemontese bulls were included in the AI testing programme and compared with Braunvieh- and Simmental-M-bulls. Data included progeny from 47 bulls, 7936 calvings, 1137 animals with carcass gains, and 130 dissected carcasses. If calving performance and net gains are considered, the M-bulls compete well with the foreign breeds. If, in addition, the amount of meat in the carcass is taken into account, then Charolais and Piemontese crosses are superior. The problem is one of distributing gains and losses among calf producers, feeders and butchers. It needs specially tested bulls with emphasis on ease of calving out of the specialized beef breeds or sire lines to persuade the dairy farmer to cross his cows.  相似文献   

9.
Pregnancy is characterized by transient changes in the maternal immune system, also evident at peripheral level. The present study analyzes the kinetics and possible factors affecting peripheral white blood cell populations throughout pregnancy in a herd of high-producing dairy cows chronically infected or not with Neospora caninum. We examined 54 pregnant parous cows: 29 Neospora-seronegative and 25 Neospora-seropositive cows. Blood samples were collected on Days 90, 120, 150, 180 and 210 of gestation. General Linear Model (GLM) repeated measures analysis of variance showed that the interaction Neospora-seropositivity × parity significantly affected total leukocyte, neutrophil and monocyte counts with lower levels of total leukocytes, lower neutrophil and higher monocyte counts recorded in primiparous Neospora-seropositive cows. In addition, N. caninum-seropositive cows had significantly increased monocyte counts on Day 180 of gestation compared to seronegative ones. Other factors significantly associated with changes in total and/or differential leukocyte profiles were period of pregnancy, season, twin pregnancy and milk production. In conclusion, a parity-associated effect of chronic N. caninum infection was observed on peripheral blood cell profiles in dairy cattle during gestation.  相似文献   

10.
The present study sought to determine: (i) the effects of Neospora caninum infection and twin pregnancy on plasma pregnancy‐associated glycoprotein‐2 (PAG‐2) concentrations throughout pregnancy and (ii) whether plasma PAG‐2 concentrations could predict abortion in N. caninum‐infected cows. The study was performed on a commercial Holstein‐Friesian dairy herd in northeastern Spain and the final data included those recorded in 53 non‐aborting and 19 aborting animals. Blood samples were collected immediately before pregnancy diagnosis (on Days 40, 90, 120, 150, 180 and 210 post‐insemination) in non‐aborting cows or until the time of abortion detection in aborting cows. General lineal models (GLM) repeated measures anova revealed the different behaviour of PAG‐1 and PAG‐2, and significant effects of Neospora seropositivity, cool season and twin pregnancy on plasma PAG‐2 concentrations throughout gestation (between‐subject effects). In addition, based on the odds ratios, the likelihood of abortion increased in Neospora‐seropositive cows (by a factor of 7.0) compared to seronegative animals and decreased in cows with a high plasma PAG‐2 concentration (>4.5 ng/ml) on Day 120 of pregnancy (by a factor of 0.24), compared to the remaining cows. In conclusion, there is a relationship between plasma PAG‐2 concentrations and the risk of abortion in Neospora‐infected dairy cows. Thus, plasma PAG concentrations measured using anti‐boPAG‐2 antiserum on Day 120 of gestation could serve as an indicator of the abortion risk in N. caninum infected animals; values <4.5 ng/ml indicating a high risk of abortion in chronically infected animals.  相似文献   

11.
The possible direct relationship between climate variations and abortion in Neospora caninum-infected cows has not been studied. The objective of this study was to determine whether climate changes could be a risk factor for abortion in N. caninum-infected cows, and was based on yearly serological screening for neosporosis and on the confirmation of N. caninum infection on aborted fetuses in two high-producing dairy herds with a mean 27% seroprevalence of N. caninum antibodies. The final population study was comprised of 357 pregnancies in seropositive animals. Logistic regression analysis indicated no significant effects of herd, N. caninum antibody titre, climate variables during the first and third trimesters of gestation, mean and maximum temperature-humidity index values during the second trimester of gestation, and previous abortion on the abortion rate. Based on the odds ratio, a 1-unit increase in lactation number yielded a 0.85-fold decrease in the abortion rate. The likelihood of abortion was 1.9 times (1/0.54) lower for pregnant cows inseminated with beef bull semen compared with Holstein-Friesian bull semen. The likelihood of abortion decreased significant and progressively by factors of 0.5, 0.41 and 0.3 for the respective classes 40-49, 30-39 and <30 rainfall mm during the second trimester of gestation (using the class >or=60 rainfall mm as reference). As a general conclusion, it seems that increased rainfall in a dry environment can compromise the success of gestation in N. caninum-infected cows. Attempts should therefore be made to reduce environment effects during the second trimester of gestation, a period in which the immune response of cows is diminished.  相似文献   

12.
This work estimates the economic losses due to Neospora abortions in the humid pampa region of Argentina. The total dairy and beef cattle population at risk of abortion is 1,771,326 and 9,726,684 head, respectively. In dairy cattle, there was an 8 % risk of experiencing abortion due to a variety of causes, but 16.5 % of them were due to Neospora caninum. The economic losses were estimated at US$1,865 (range, 1,400–2,331) per abortion, which equates to a total loss of US$43,607,430 (range, 15,622,600–194,412,390) for the dairy industry at the humid pampa region of Argentina. In beef cattle, the overall risk of abortion was estimated to be 4.5 % for all pregnancies, whereas 6.7 % are specifically due to N. caninum, with an economic loss of US$440 (range, 150–730) per abortion. This amounts to an annual loss to the beef industry of US$12,903,440 (range, 1,130,700–42,070,630) in the same area. The results of this study show that Neospora infections and thus abortions cause severe economic impacts in the dairy and beef industries in the humid pampa region of Argentina, which is one the most important areas of cattle production in the world.  相似文献   

13.
We report herein a survey in which cultures of bovine reproductive tracts for Ureaplasma diversum and mycoplasmas were carried out in order to better understand the role of these organisms in granular vulvitis (GV). Samples cultured were vulvar swabs from clinically normal cows or ones with GV, preputial swabs or raw semen from bulls, and abomasal contents of aborted fetuses.

Ureaplasma diversum was isolated from 104 (43.3%) of 240 dairy cows, 32 (27.1%) of 118 beef cows, 43 (47.2%) of 91 beef heifers, 23 (67.6%) of 34 beef bulls, and three (60%) of five dairy bulls. Mycoplasmas were isolated from 18 (7.5%) dairy cows, two (1.6%) beef cows, three (8.8%) beef bulls, and one dairy bull. No isolation was made from 97 aborted fetuses. For 65 dairy cows and 30 beef heifers with vulvar lesions, the isolation rates for ureaplasmas of 62.5% and 69.7%, respectively, were significantly higher (X2) than those for normal animals (37.5% and 30.3%). On immunofluorescent serotyping of 137 of the 205 isolates, there were 66 in serogroup C (strain T44), 18 in serogroup B (strain D48), eight in serogroup A (strain A417 or strain 2312), 14 cross-reacting, and 31 that were not identified. It was concluded that U. diversum is commonly present in the lower reproductive tract of beef/dairy cattle in Saskatchewan and is associated with granular vulvitis.

  相似文献   

14.
In this study, semen samples from 25 bulls that had passed a breeding soundness evaluation were analyzed for the presence or absence of a 31-kDa protein, known as fertility-associated antigen (FAA), on spermatozoal membranes. Eighteen bulls had FAA on sperm (FAA-positive) and seven were devoid of FAA on sperm (FAA-negative). A single ejaculate from each bull was extended and frozen with 25 to 30 x 10(6) sperm in .5-mL straws. Crossbred replacement heifers (n = 865) were estrus-synchronized and artificially inseminated either at timed AI or 12 h after they were detected in estrus. Mature cows (n = 285) were inseminated 12 h after they were detected in estrus during a 45-d AI period. Pregnancy rates (pooled) to first AI service for females (n = 764) inseminated with FAA-positive sperm were 65.6% and were 49.7% for females (n = 386) inseminated with FAA-negative sperm (P < .005). Among the estrus-synchronized replacement heifers, pregnancy rates to synchronized AI service for heifers (n = 550) inseminated with FAA-positive sperm were 62% and were 45.7% for heifers (n = 315) inseminated with FAA-negative sperm (P < .005). These data indicate that pregnancy rates to first AI service at spontaneous and synchronized estrus are higher when using semen from bulls with detectable FAA on spermatozoal membranes compared to semen from bulls devoid of FAA on membranes. Fertility-associated antigen is an important determinant for fertility potential of sperm from bulls to be used in AI breeding programs.  相似文献   

15.
AIM: To monitor pregnancy in a group of rising 2-year-old dairy heifers on a farm on which abortion due to Neospora caninum was known to occur in previous years.

METHODS: A prospective cohort study group of 164 rising 2-year-old heifers was pregnancy-tested and blood-sampled at 4–5-week intervals throughout gestation. Sera were tested for antibodies to N. caninum at 3–4-month intervals, using an enzyme-linked immunosorbent assay (ELISA). When loss of pregnancy was detected, an N. caninum indirect fluorescent antibody test (IFAT) was conducted retrospectively on stored sera collected the month before abortion, the month abortion was detected, and for the following 2 months, from heifers that aborted. All fetal and placental material detected following abortion was subjected to gross post-mortem and histopathological examination.

RESULTS: Eleven of 18 (61%) heifers that were seropositive and 4/146 (3%) heifers that were seronegative to N. caninum by ELISA, aborted. The relative risk for abortion among ELISApositive heifers was 23.6. Abortion occurred predominantly between Days 120 and 152 gestation among the ELISA-positive heifers and throughout gestation among the ELISA-negative heifers. IFAT titres rose around the time of abortion in most of the heifers that were previously seropositive by ELISA, but dropped rapidly again in post-abortion samples. IFAT titres among 4/6 ELISA-positive heifers that did not abort increased, but later in gestation than the time other heifers aborted. IFAT titres remained negative in heifers that aborted that were ELISAnegative.

CONCLUSIONS: Heifers that were seropositive to N. caninum by ELISA had a much greater risk of abortion than seronegative heifers. Most seropositive heifers showed evidence of a reactivation of infection during pregnancy. High (≥1:2,000) N. caninum IFAT titres also occurred in non-aborting heifers.

CLINICAL RELEVANCE: Culling of replacement heifers seropositive to N. caninum may be a cost-effective strategy for minimising risk of abortion. Pregnancy testing heifers before 5 months gestation may overestimate the number that calve in N. caninum-infected herds, but would assist in documenting the occurrence of abortion. Reliance on a high (>1:2,000) IFAT titre to rule-in N. caninum as a cause of abortion is likely to produce false-positive results.  相似文献   

16.
This case-control study aimed at assessing the relative association of Neospora caninum and Brucella species exposure with reproductive disorders. The study was carried out between October 2011 and June 2012 on 731 dairy cows sampled from 150 dairy farms in selected 17 conurbations of Ethiopia. Two hundred sixty-six of the cows were categorized as cases based on their history of abortion or stillbirth while the remaining 465 were controls. The presence of antibody to N. caninum was screened using indirect ELISA, while Brucella spp. exposure was assayed serially using Rose Bengal Plate Test and Complement Fixation Test. Exposure to N. caninum was more frequently observed among cases (23.8 %) than controls (12.7 %), while no significant difference (p?>?0.05) was noted for Brucella exposure between the two groups. Moreover, the proportion of cows with disorders like retention of fetal membrane, endometritis and increased inter-calving period were significantly higher (p?<?0.05) among Neospora seropositive cows. In conclusion, the finding discloses the strong association of N. caninum with reproductive disorders compared to Brucella spp. exposure. However, neither N. caninum nor Brucella spp. could explain the majority (73.2 %) of the reported abortions and stillbirths in cattle. Hence, this observation underscores the need for more intensive investigation on the identification of causes of the aforementioned disorders in dairy cattle of Ethiopia.  相似文献   

17.
The objective of this study was to determine if factors associated with the biostimulatory effect of bulls alter breeding performance of primiparous, suckled beef cows using a progestin-based estrous synchronization protocol. We tested the hypotheses that the estrous synchronization response and AI pregnancy rates differ among cows exposed to bulls, continuously exposed to bull urine, and exposed to fence-line contact with bulls or cows not exposed to bulls or bull urine. Data were collected from 3 experiments performed over consecutive years. Cows were assigned to the following treatments: bull exposure (BE; n = 26) or no bull exposure (NB; n = 25) in Exp. 1, bull urine exposure (BUE; n = 19) or steer urine exposure (SUE; n = 19) in Exp. 2, and fence-line contact with bulls (BFL; n = 26) or no bull exposure (NB; n = 26) in Exp. 3. Synchronization protocols in each experiment included the use of a controlled internal drug release device (d -10), PGF(2alpha) (d -3), and GnRH and fixed-time AI (TAI; d 0). Cows that were observed in estrus by 60 h after PGF(2alpha) were inseminated 12 h later. Cows not observed in estrus by 60 h after PGF(2alpha) were TAI at 72 h and given GnRH (100 mug). Pregnancy was determined by ultrasonography 35 d after TAI. In Exp. 1, 2, and 3, cows were exposed directly to bulls, bull urine, or bull fence-line contact for 35, 64, and 42 d, respectively. Data were analyzed between treatments within each experiment. The proportion of estrous cycling cows did not differ between treatments at the beginning of each experiment; however, more (P < 0.05) BE and BFL cows were estrous cycling at the beginning of the estrous synchronization protocol than NB cows in Exp. 1 and 3. The proportion of cows that showed estrus and interval to estrus after PGF(2alpha) did not differ between treatments in Exp. 1 and 3. However, in Exp. 2, more BUE cows tended (P = 0.09) to have shorter intervals to estrus and to exhibit estrus after PGF(2alpha) than SUE cows. Overall, AI pregnancy rates were greater (P < 0.05) for BE and BUE cows than for NB and SUE cows in Exp. 1 and 2, respectively. There was no difference in AI pregnancy rates between BFL and NB cows in Exp. 3. The presence of bulls and exposure to bull urine appeared to improve breeding performance of primiparous beef cows using a progestin-based estrous synchronization protocol, whereas fence-line bull exposure was insufficient to cause this biostimulatory effect. We propose that a novel urinary pheromone of bulls may be responsible for the enhancement of fertility in the primiparous, postpartum cow.  相似文献   

18.
The aim of this study was to determine the seroprevalence of Neospora caninum antibodies and its effects on reproductive parameters in cows in intensive dairy herds in Dakar. Randomised blood samples were taken for serology from 196 cows in four herds with a history of sporadic abortion. All of the sera were assayed for antibodies against N. caninum, Candida guillermondii, Coxiella burnetii, and Chlamydophila sp. The associations between serostatus and reproductive parameters (abortion, number of inseminations to conception, and calving to conception interval) were assessed over a period of 5 years (2004–2008). The seroprevalence of N. caninum antibodies in dairy cattle was 17.9%. The local Gobra breed and crossbreeds had higher levels of N. caninum antibodies than exotic breeds (p < 0.05). For the most recent pregnancies, seropositive cows required more inseminations to establish conception than seronegative cows (p < 0.05). The results indicate that dairy cattle from Dakar are exposed to N. caninum. Neosporosis should, therefore, be systematically considered as a cause when the calving to conception interval is prolonged.  相似文献   

19.
This report describes a retrospective study based on serological screening, performed on a Neospora‐associated abortion episode over a 12‐month period in a dairy herd in north‐east Spain. During the 1‐year study period, the overall abortion rate for the herd was 23.2% (38 abortions of 164 diagnosed pregnancies). The data analysed were those derived from blood samples collected from the whole herd (n = 237) and from diagnosed pregnancies. Antibodies to Neospora caninum were found in 35.4% of the cattle with 44% of seropositive pregnant animals aborting over 1‐year period. Based on the odds ratio, the risk of abortion was 12.2 times higher (P < 0.0001) in the Neospora‐seropositive animals than in seronegative animals and significantly higher during the second term of gestation (P < 0.01) than during the first and third terms. Abortions were not found to be associated with parity status or season of pregnancy, and the common risk factors associated with pregnancy loss in the geographical area of the study. Age‐related differences in N. caninum seroprevalence were not statistically significant, indicating vertical transmission as the main route of infection. Indeed, a high percentage of congenitally infected offspring was observed (90.6%) and the farm had been free of dogs for the last 7 years. Our results suggest that, when a dairy herd shows an increased incidence of abortions due to Neosporosis, maternal serology can be a good indicator of the abortion risk in individual cows, and that the effects of factors normally related to abortion, such as parity and pregnancy season, may be masked.  相似文献   

20.
Neosporosis is a major cause of abortion in cattle all over the world. Congenital transmission as well as horizontal transmission by ingestion of oocysts has been described. The detection of Neospora caninum DNA in bull semen warrants the investigation of possible transmission through the use of contaminated semen. In this experiment four cows were artificially inseminated with frozen-thawed semen contaminated in vitro with viable N. caninum tachyzoites (group A) and four control cows were inseminated with tachyzoites-free frozen-thawed semen, from the same bull (group B). Serum samples were collected 15 days before the artificial insemination (AI) and at days 10, 14, 21, 28, 45, 60 and 75 post-insemination. All sera samples were tested for neosporosis by direct agglutination test (DAT). Three of the cows from group A had negative DAT titers (< or =1:20) in all of the samples, while the fourth cow from this group had a low titer of antibodies (1:80) at day 10, and became negative at day 45, suggesting a stimulation of the immune system by the tachyzoites placed in uterus, rather than the induction of an infection. All of the cows from group B had negative DAT titers (< or =1:20) in all of the samples. These results suggest that transmission of neosporosis by artificial insemination with frozen-thawed semen is an unlikely event.  相似文献   

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