Shedding of Coxiella burnetii in ewes in two pregnancies following an episode of Coxiella abortion in a sheep flock.

Coxiella burnetii infection in pregnant sheep typically causes abortion or the birth of weak lambs. Two C. burnetii-related abortions in a group of 34 pregnant ewes were reported at their first lambing in our research institute. The seroprevalence of C. burnetii infection and bacteria shedding were investigated using an ELISA and PCR, respectively, during the course of two subsequent pregnancies. None of the ewes examined seroconverted from negative to positive at the time of the second and the third parturition and most of the ewes that were seropositive at the abortion episode remained positive throughout the investigation. The two successive pregnancies resulted in the birth of healthy lambs without PCR evidence of Coxiella infection from placenta and vaginal swabs taken postpartum. PCR assay performed on vaginal swabs taken from all animals 1, 5 or 12 days after the second lambing were also negative for Coxiella. However, one ewe that had previously experienced C. burnetii shedding at the first lambing excreted the bacteria in the genital tract after the third parturition. The bacteria could not be detected by PCR in milk and faecal samples taken up to 12 days after both parturitions.     

Relationships between the shedding of Coxiella burnetii, clinical signs and serological responses of 34 sheep

Two abortions associated with Coxiella burnetii occurred in a group of 34 pregnant ewes. The seroprevalence of C. burnetii infection was studied by using an ELISA and the immunofluorescence (IF) assay was applied to the contents of vaginal swabs. In addition, a PCR assay, with primers based on a transposon-like repetitive region of the C. burnetii genome (trans-PcR), was used for the highly sensitive and specific detection of C. burnetii in vaginal swabs, milk and faeces. Of the 34 animals tested at parturition, eight (24 per cent) were positive by ELISA, 11 (32 per cent) were positive by IF, and 15 (44 per cent) were positive when the vaginal swab extract was subjected to the trans-PCR assay. C. burnetii was therefore detected by PCR in the vaginal swabs of seven seronegative ewes. However, five weeks after lambing, 16 (47 per cent) of the animals tested were ELISA positive but only two animals (6 per cent) were positive by PCR. Among the ELISA- and PCR-positive animals, eight (25 per cent) shed coxiella in their milk and six (18 per cent) did so in their faeces.     

Shedding and serological patterns of dairy cows following abortions associated with Coxiella burnetii DNA detection

To describe both shedding and serological patterns following abortions detected as being associated with Coxiella burnetii (Cb), 24 cows experiencing an abortion due to Cb were followed over a one month period. Samples taken on the day of abortion (D0) were followed 3-fold by weekly samplings from day 14 (D14) to D28 after the abortion. Milk and vaginal mucus were collected at each weekly sampling and tested using real-time PCR while blood samples were collected 2-fold on D21 and D28 and tested using ELISA. We found a very short duration of C. burnetii shedding in vaginal mucus after abortion, highlighting the need to collect samples as rapidly as possible following an abortion to avoid false negative results. In contrast with previous results, concomitancy of vaginal and mucus shedding was frequent, especially for cows shedding a high bacterial load on DO leading to the hypothesis that the clinical onset of the infection influences the modalities of Cb shedding. Lastly, serological results indicating a lack of sensitivity to detect Cb shedder cows (especially for cows for which Ct values were high) suggest that ELISA is not a useful tool to diagnose abortions at the individual level.     

A mucosal disease-like condition in lambs with hairy shaker disease

Extract

A hairy shaker disease outbreak occurred on a Southland farm in spring 1992 in a flock of 100 2-year-old ewes and 350 older ewes. About 80 of the 2-year-old ewes produced lambs that were small and coarse-fleeced but robust. Most of these lambs were born early in the season. The lambs born later in the season appeared normal.     

Losses related to the ingestion of lincomycin-medicated feed in a range sheep flock

Because of an episode of abortion caused by a tetracycline-resistant Campylobacter jejuni, lincomycin was mixed into a barley pellet and fed to 3,000 range ewes at a dosage of 225 mg/ewe/day. After the second feeding, a number of ewes were anorectic and diarrheic, and 6 were dead. Necropsies revealed congestion and hemorrhage of the entire gastrointestinal tract. The feeding of the medicated pellets was discontinued immediately. Sick ewes were treated with antihistamines and corticosteroids, but they did not recover, and many died during the next several weeks. Lambs born within the first 7 days after the incident were alert and vigorous. Dams did not produce milk and many died during or after parturition. Later, however, lambs were born dead or weak, and abortions of autolyzed lambs began. Affected ewes examined 3 weeks later had salmonellosis and/or toxic tubular nephrosis associated with an oxalate-like crystal. The flock had been grazed on range infested with Halogeton glomeratus just before treatment with lincomycin, and it also had a history of Salmonella-related abortions. The deaths finally ceased after a month. Approximately 2,000 ewes and 3,200 lambs were lost, resulting in an economic loss of $550,000.     

Effect of passive transfer of maternal immune components on infection with ovine herpesvirus 2 in lambs

OBJECTIVE: To define the role of passively tranferred immunity in protection against early infection with ovine herpesvirus 2 (OvHV-2) in lambs. ANIMALS: 15 adult sheep and 34 lambs. PROCEDURES: 2 groups of animals were used, including 15 lambs born to OvHV-2-free ewes and 19 lambs born to OvHV-2-positive ewes. After nursing colostrum, all lambs and their dams were introduced into a flock positive for OvHV-2. Blood was obtained from the lambs every 2 weeks and examined by PCR assay and competitive inhibition ELISA. RESULTS: None of the animals had positive results by PCR analysis for samples obtained approximately 2 weeks after introduction into the flock. In the group of lambs from OvHV-2-infected ewes, 5 of 19 had positive results at 1 month of age and 17 of 19 by 5 months of age. In the group of offspring from OvHV-2-negative ewes, only 1 of 15 had positive results at 1 month of age, and the number reached 12 of 15 by 5 months of age. All lambs in both groups had positive results by 6 months. An active antibody response to the virus was detected in animals within 3 weeks after viral DNA became detectable in the blood. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis suggests that passively transferred immunity does not play an important role in the delay of infection with OvHV-2 in lambs. Age also does not seem to influence susceptibility. The rate of infection in young lambs may simply be a reflection of the intensity of viral exposure in their environment.     

Demonstration of lateral transmission of scrapie between sheep kept under natural conditions using lymphoid tissue biopsy

Scrapie free adult sheep were introduced to a sheep flock specifically maintained to maximise scrapie infection. Native born sheep of the highly susceptible VRQ/VRQ genotype in this flock show highly efficient transmission, evidenced by 100% infection, with an age at death of less than 2 years. Infection in introduced sheep was identified by biopsy of tonsilar and nictitating membrane lymphoid tissue. Progeny of these sheep were monitored and clinical disease confirmed by examination of the brain using routine diagnostic methods. Na?ve sheep of New Zealand origin introduced to the flock in adulthood became infected, demonstrating that lateral transmission had occurred. Lambs born to introduced ewes became infected and died at the same age as lambs born to native ewes, consistent with lateral transmission of scrapie to lambs. Although maternal transmission cannot be totally excluded for the lambs in this study, the data are consistent with lateral transmission being the most important means of spread leading to the high incidence of scrapie observed in this flock.     

A census of the prevalence of vaginal prolapse in sheep flocks in the Borders region of Scotland

A postal census of vaginal prolapse in sheep flocks in the Borders region of Scotland yielded 540 replies from 963 owners (56 per cent). There were 262,250 ewes in 976 flocks and 2573 vaginal prolapses were reported. Analysis of the data revealed that 390 (40 per cent) of the flocks had no vaginal prolapses and in 237 (24.3 per cent) the reported prevalence was between 0.1 per cent and 1.0 per cent. Only 63 (6.5 per cent) of flocks had a greater than 5 per cent prevalence of vaginal prolapses. The greatest number of prolapses occurred in an upland flock of greyface ewes mated with Suffolk tups with 50 cases among 700 ewes (7.1 per cent) and the highest prevalence was in an upland Scottish blackface flock of ewes bred with Suffolk tups with 15.2 per cent (35 cases among 230 ewes). There were marked breed differences; very few hill breeds were affected and most cases occurred in greyface ewes mated with Suffolk tups.     

The effects of bovine viral diarrhoea-mucosal disease (BVD) virus on the ovine foetus

Bovine viral diarrhoea-mucosal disease (BVD) virus has been incriminated as a cause of abortion, hairy birth coat and unthriftiness in sheep. Intravenous inoculation of 40 ewes 34 to 45 days pregnant with the V/TOB strain of virus produced death in two of four foetuses 9 days after inoculation and in all but one of 31 foetuses between 11 and 56 days. The highest levels of virus in placentomes and foetal tissues occurred between 9 and 15 days after inoculation and in foetal fluids between 11 and 18 days. Virus was not detected in any foetus later than 21 days after inoculation. Groups of 10 ewes infected between 59 and 62 days (Group B) and 70 and 76 days (Group C) of gestation had 73% and 62%, respectively, of abortions or perinatal foetal deaths. Birth weights of lambs born to infected ewes in groups B and C were significantly lower than those born to uninfected control ewes. Virus was recovered consistently from the cotyledons of the foetal membranes of live lambs, and irregularly from the tissues of full term foetuses that were dead at birth but on no occasion from mummified foetuses. There were no specific gross or microscopic lesions in tissues selected from aborted foetuses and the results highlight the difficulties associated with the diagnosis of BVD abortions and perinatal death of foetuses under field conditions.     

Lifetime production of 1/4 and 1/2 Finnsheep ewes from Rambouillet, Targhee and Columbia dams as affected by natural attrition

Lifetime production of first-generation 1/4 and 1/2 Finnsheep crossbred ewes from Rambouillet (R), Targhee (T) and Columbia (C) dams was compared with that from randomly selected purebred R, T and C ewes. All 1,190 ewes, representing nine breed groups, were managed under range conditions and mated annually to Suffolk rams. Lifetime production was evaluated as the total lamb and total wool production per ewe from the time each entered the breeding flock at 7 mo of age through the period each remained in the flock (potentially seven producing years). Culling was for debilitating unsoundness only. The study was designed to determine the average lifetime production per breed group as affected by natural ewe attrition. Orphan-reared lambs were not included in lamb production nor were foster lambs, except those actually born in and reared by the groups. Differences among pooled breed groups (1/4 Finns, 1/2 Finns and purebreds) were not significant for average final age in the flock (5.1, 5.1 and 4.9 yr, respectively), but differences were significant (P less than .01) for lifetime lamb and wool production. Average lifetime fleece weights of 1/4 and 1/2 Finn ewes were only 95 and 82% as high, respectively, as those of purebreds. However, 1/4 and 1/2 Finn ewes had 34 and 46%, respectively, higher numbers of lambs weaned (at 130 d) and 30 and 38% higher total weight of lamb weaned than purebreds.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemimelia and low marking percentage in a flock of Merino ewes and lambs

Hemimelia at a prevalence of 11% of lambs marked, and low marking percentage (51%) was observed in a flock of mixed age Merino ewes and their lambs. Hemimelia occurred in one or 2 limbs of affected lambs. Lambs from other flocks on the farm were unaffected, and the condition was not reported from other farms. The condition had not occurred in the past, and has not recurred. No infectious or hereditary factors were implicated in the aetiology of the condition. Grazing Western Australian Blue Lupin stubble by the affected flock during and after joining was the only known difference between this flock and others on the farm.     

An investigation of the possible effects of subclinical iodine deficiency on ewe fertility and perinatal lamb mortality

A controlled supplementation trial was performed in an assumed iodine-deficient Romney ewe flock in the Manawatu. Significantly more twin litters were born to iodine-supplemented ewes than to control ewes. Furthermore, the perinatal mortality rate in lambs born to iodine-supplemented dams was significantly lower than in lambs born to control dams. Ewe age and the use of different lambing paddocks for iodine-supplemented and control ewes may have been confounding factors. In both iodine-supplemented and control ewes, serum T3, and T4, concentration values remained above the currently used normal range throughout the trial period.     

Goats may experience reproductive failures and shed Coxiella burnetii at two successive parturitions after a Q fever infection

Q fever is a zoonosis caused by the obligate intracellular bacterium, Coxiella burnetii. Aborting domestic ruminants are the main source of human infection. In January 2003, an abortion episode occurred in a dairy caprine herd where 18/60 (30%) goats experienced reproductive problems: 4/60 (7%) aborted and 14/60 (23%) had stillbirths. Serological screening for abortion-related infectious diseases suggested Q fever. The diagnosis of C. burnetii infection was confirmed with PCR based on the occurrence of C. burnetii shedding into vaginal mucus, faeces and colostrums taken after kidding from the affected animals. The pregnancy following this episode resulted in one abortion and four stillbirths; three of those goats had already experienced reproductive failure during the previous kidding season. The seroprevalence of C. burnetii infection and the bacteria shedding were investigated using both ELISA and PCR assays, respectively, during the course of the initial and subsequent kidding seasons. Serological testing, performed on the whole herd 6 weeks after the abortion episode, showed 48/60 (80%) of ELISA positive goats. PCR assay performed on both vaginal swab and milk samples showed that the bacterium was shed for almost four months after the outbreak. C. burnetii DNA was also amplified from vaginal swab and milk samples taken from goats after the second kidding season. Furthermore, the bacteria were found into 14 vaginal swabs and 12 milk samples taken from infected females at both kidding seasons.     

An investigation of the possible effects of subclinical iodine deficiency on ewe fertility and perinatal lamb mortality

A controlled supplementation trial was performed in an assumed iodine-deficient Romney ewe flock in the Manawatu. Significantly more twin litters were born to iodine-supplemented ewes than to control ewes. Furthermore, the perinatal mortality rate in lambs born to iodine-supplemented dams was significantly lower than in lambs born to control dams. Ewe age and the use of different lambing paddocks for iodine-supplemented and control ewes may have been confounding factors. In both iodine-supplemented and control ewes, serum T₃ and T₄ concentration values remained above the currently used “normal” range throughout the trial period.     

Flock dynamics of desert Barki sheep in relation to age structure

Reproduction data of 8689 ewe records spread over 40 years (from 1960 to 2000) representing 2952 breeding Barki ewes were used in this study. The flock belonged to the Desert Research Center in Egypt. Flock dynamics of nine age groups (2–10 yrs) were assessed. Two parameters were used to evaluate flock dynamics, net reproduction rate (R_o) (number of ewe- lambs reaching joining age and produced by each ewe during its lifetime in the flock) and intrinsic rate of increase (r_m) (flock growth when no resource is limiting). Age of ewe had a highly significant (P < 0.01) effect on number of ewes lambing per ewe joined (E_PJ), number of lambs born per ewe joined (L_BJ), number of lambs weaned per ewe joined (L_WJ) and number of ewe lambs reaching joining age per ewe joined (L_EJ.J). All estimates tended to increase with dams age up to four years and decreased thereafter. The results of R_o and r_m showed that the studied flock must consist of 5 age groups to maintain its size and replace itself. It may be recommended to cull the breeding ewe at the age of 6 years to accelerate genetic improvement.     

Efficacy of a vaccine to prevent Chlamydia- or Campylobacter-induced abortions in ewes

In a sheep flock, Chlamydia psittaci, Campylobacter fetus, Ca jejuni, and Salmonella dublin caused abortions. A vaccine that contained C psittaci type I from 2 sources: a cow with pneumonia and an aborted ovine fetus, Ca fetus, Ca jejuni, and 4 strains of K99 Escherichia coli was given to 240 ewes before they were bred. All fetuses, placentas, and lambs, that died within 36 hours of birth were examined for infectious agents. Of 55 abortions, 30 (55%) were caused by Chlamydia or Campylobacter spp; 25 of the 30 (83%) abortions took place in the nonvaccinated group (n = 240). Forty-five more lambs survived in the vaccinated group than in the nonvaccinated group. Abortion rates for Chlamydia and Campylobacter spp (2.1 vs 10.4% in vaccinated and nonvaccinated groups, respectively) were significantly different (P = 0.003). Abortion rates for S dublin were not significantly different between groups. The Salmonella epizootic was controlled quickly by sanitation and treatment procedures. The vaccine was at least 80% efficacious against Chlamydia and Campylobacter spp and appeared to be protective.     

Immunization against polyandroalbumin leads to increases in lambing and tailing percentages

A series of 10 farm trials was conducted in which the lambing performance of ewes immunised against polyandroalbumin was compared with that of untreated ewes in the same flock. The trials show that polyandroalbumin treatment is a reliable method of increasing lambing and tailing percentages in New Zealand flocks. An average of 39 extra lambs born per 100 ewes tupped was achieved on farms where ewes were given two treatments about four weeks apart and rams were introduced 18-26 days after the second dose. On farms where rams were introduced less than 12 days after this booster injection an average of 19 extra lambs born per 100 ewes tupped resulted. On farms where rams were introduced at 18-26 days post booster injection an average of 35 extra lambs were tailed for every 100 ewes tupped. The response for immunization increased in direct relation to the liveweight of the ewes at tupping.     

Investigations about kind and frequency of mechanical dystocia in ewes with special regard to the vaginal prolapse ante partum

The incidence of dystocia from ewes in nine lambing periods (1992-2000) was recorded at an obstetrical clinic. First we analysed parturition difficulties in normal pregnant sheep (group 1, n = 229). In the second group parturitions of ewes with vaginal prolapse ante partum were investigated (n = 129). In group 1 maternal causes of dystocia occurred more often than fetal ones (50% maternal, 45% fetal). In maternal parturition difficulties ringwomb was the dominating reason (64%), while abnormal presentations, position and/or posture of the lambs occurred most frequently in fetal dystocia (67%). But there was no statistical influence of age and number of parturitions in both groups. The average of the first notice of prolapsed vaginal tissue was 11 days before lambing. There was a predominance in the affection of sheep at first and second pregnancy (52%). Only 26% of the group 2 sheep had a spontaneous delivery. In 58% of the cases a dystocia was diagnosed. A preterm caesarean section had carried out in 12%, five ewes died before parturition because of septicemia (4%). Sheep suffering from vaginal prolapse ante partum showed maternal caused dystocia significant more frequently than members of group 1 (p < 0.001), with ringwomb as dominating reason (70%). The number of born lambs was significant higher in group 2 than in group 1 (p = 0.019).     

Evaluation of the ovine callipyge locus: IV. Genotypic effects on reproductive traits

A resource population of ewes derived from Dorset and Romanov grandparents was generated over 5 yr to provide genotypic and phenotypic data to estimate effects of each callipyge genotype on component traits of reproduction. Effects on ovulation rate were estimated from data recorded by examination of ovaries from serially slaughtered ewe lambs (n = 174) born in 1994 and 1995. Productivity and longevity through 5 yr of age were recorded on a total of 265 F2 ewes produced in 1996 through 1998. Number of lambs born, birth weights, and weaning weights of lambs were calculated for each ewe. Weaning weight was recorded for each lamb and adjusted for age to 56 and 32 d for dam- and nursery-reared lambs, respectively. Longevity was determined as a binary trait based on the presence or absence of the ewe in the breeding flock at 5 yr of age. Ewes generated 937 records for breeding weight and 925 records for conception rate, which was determined on ewes exposed and still present at the start of each lambing season. Seven hundred seventeen records were analyzed for traits based on the number of ewes lambing. Genotypes for the causative callipyge mutation were determined using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry assay. Each ewe was classified into 1 of 4 genotypes; NMatNPat, NMatCPat, CMatNPat, or CMatCPat, where N represents wild type and C represents the mutant allele. The mean ovulation rate of the ewe lambs genotyped NMatNPat was greater (P < 0.02) than that exhibited by NMatCPat; however, the estimated difference of 0.25 ovum in the ewe lambs did not affect the number born. The live weight of NMatCPat ewes at breeding was 2.5 kg less than that of other genotypes (P < 0.01). The callipyge genotype class did not significantly affect conception rates, fecundity, maternal ability, or ewe longevity. Maintaining a ewe flock to produce homozygous mutant rams for use in terminal sire mating systems presents no unusual problems from a reproduction standpoint.     

The bacteriology and serology of ewes inoculated with viable Brucella ovis organisms

A series of 10 farm trials was conducted in which the lambing performance of ewes immunised against polyandroalbumin was compared with that of untreated ewes in the same flock. The trials show that polyandroalbumin treatment is a reliable method of increasing lambing and tailing percentages in New Zealand flocks. An average of 39 extra lambs born per 100 ewes tupped was achieved on farms where ewes were given two treatments about four weeks apart and rams were introduced 18–26 days after the second dose. On farms where rams were introduced less than 12 days after this booster injection an average of 19 extra lambs born per 100 ewes tupped resulted.

On farms where rams were introduced at 18–26 days post booster injection an average of 35 extra lambs were tailed for every 100 ewes tupped.

The response for immunization increased in direct relation to the liveweight of the ewes at tupping.