Survival of Oocysts of Eimeria alabamensis on Pastures under Different Climatic Conditions in Sweden

The extent to which oocysts of the coccidian parasite Eimeria alabamensis can survive the winter and cause clinical coccidiosis in different parts of Sweden was investigated. Fecal samples were collected between May and July 1993 from calves on 59 farms where calves had grazed the same pasture for at least 5 consecutive years. The farms were situated in 9 regions of Sweden with different climatic conditions in the winter. On each farm, 5 samples of feces were collected from the floor of the calf-house before the calves were turned out in the spring, and again from the pasture on days 4 or 5, 8 or 9 and 10 or 11 after they were turned out. Overwintering of oocysts of E. alabamensis was considered to have occurred if an increase in the excretion rate of oocysts of this species could be demonstrated 8 to 11 days after calves had been turned out to pastures that had not been grazed since the previous autumn. Oocysts were shown to have overwintered on 27 farms, representing all 9 regions. Samples from 20 (34%) of the farms representing all the climatic regions contained more than 850000 oocysts per g of feces. This was comparable with the numbers found in animals with clinical coccidiosis due to E. alabamensis. Delaying turnout until the beginning of July did not affect the infection rate of the calves. However, calves which were turned out to pastures that had been grazed by older cattle or horses, either earlier in the spring or in previous years, excreted significantly fewer oocysts than calves which were turned out to pastures that had been grazed only by calves. A questionnaire answered by 321 dairy farmers revealed that of the 298 farmers who turned their first-season grazing cattle out to traditional pastures, 179 (60%) had used the same pasture for at least 5 years. These 179 farmers had experienced a significantly higher incidence of diarrhoea in their calves during the first 2 weeks at pasture than those farmers who had used different pastures.     

The annual cycle of shedding Eimeria oocysts by European bison (Bison bonasus) in the Bialowieza Primeval Forest, Poland

Between April 2008 and March 2009, we analyzed the pattern of coccidian oocysts present in the feces of the European bison (Bison bonasus L., 1758) and found 4 species (Eimeria bovis , E. canadensis, E. ellipsoidalis, E. zuernii) previously reported from this host and 3 species (Eimeria alabamensis, E. cylindrica, E. pellita) that are new host and locality records. All the species occurred in bison females, and only 4 occurred in males; E. bovis was the most prevalent in both sexes. The overall prevalence of Eimeria spp. invasion reached 34.7% in cows and 13.9% in bulls. The highest prevalence was noted in early spring, with a peak in April, and the lowest in late autumn and winter. The oocyst count per gram of feces (OPG) varied from 50 to 1,350; no symptoms of clinical coccidiosis were observed. We found a significant influence of winter aggregations of bison on shedding of coccidian oocysts. The prevalence and OPG values were higher in bison congregating in large numbers around winter-feeding sites in comparison to other sites. We suggest that the coming together of cows during the growing season impacts the gender-related differences in prevalence and the number of coccidian species involved. This observation probably results from an increased production of oocysts by sub-clinically infected individuals in high-density bison populations.     

Occurrence and strain diversity of thermophilic campylobacters in cattle of different age groups in dairy herds

AIMS: To investigate the occurrence and numbers of thermophilic campylobacters excreted by cattle in dairy herds, and to assess the strain diversity within herds. METHODS AND RESULTS: Faecal samples from 15 animals at each of 24 cattle farms were cultured quantitatively for thermophilic campylobacters and 23% of animals and 83% of farms were positive for Campylobacter jejuni. Young animals had a higher prevalence and higher faecal concentration than older animals. Serotyping and pulsed field gel electrophoresis (PFGE) of isolates showed that the most common serotypes were 2, 4-complex and 11. Serotype 2 was especially prevalent among calves (68% of the positive calves). In eight of the 20 positive herds, all isolates had the same sero- and PFGE type while, in the other herds, two to five different types were isolated. CONCLUSIONS: Significant differences were found between age groups in relation to the prevalence and numbers of excreted campylobacters, serotype distribution and strain diversity. The relatively few different strains in each herd indicate that transmission between animals is common. SIGNIFICANCE AND IMPACT OF THE STUDY: The high prevalence on cattle farms of the human pathogen C. jejuni and the wide distribution of serotype 2, the most common serotype among Danish patients, indicate that cattle might be an important reservoir for human infections. The ability of this serotype to colonize calves in high numbers further indicates that serotype 2 strains may have an advantage over other serotypes.     

Housing, Feeding and Management of Calves and Replacement Heifers in Swedish Dairy Herds

A questionnaire was sent to 1500 randomly selected dairy herds in Sweden, asking for general information about the herds, including routines from birth to first calving and also routines at breeding, calving and during the grazing period. Fifty-eight percent of the questionnaires were returned. The preweaned calves were kept in individual calf pens in 68% and in group housing systems in 28% of the herds. Pens with slatted floors were the main housing system for replacement heifers from weaning to breeding, and tie stalls from breeding to first calving. Whole milk was used in 44% and milk replacements in 42% of the herds. The calves received, as a median, 2.5 litres of milk per meal and 2 meals per day. The median age at weaning was 8 weeks. Age was the single most common criteria used for deciding both weaning and breeding time. The median age when the heifers were first turned out to pasture was 6 months. Prophylactic anthelmintic treatment was used by 65% of the herds. The most common diet for replacement heifers before calving was a combination of grain, hay and silage.     

Effects of early separation on the dairy cow and calf: 2. Separation at 1 day and 2 weeks after birth

This study investigated the effects of separating dairy calves from their mothers at 1 day (early separation) and 14 days (late separation) after birth. Behavioural observations were conducted on 24 Holstein dairy cow–calf pairs during the first 24 h after separation. Before separation, cow–calf pairs were generally inactive. After separation, cows from the late-separation treatment group showed higher rates of calling, movement and placing the head outside the pen, than cows in the early-separation group. Parity did not influence cow behaviour. During the first 2 weeks after calving, cows in the late-separation group (i.e. still with their calves) yielded less milk at milking, a difference at least partly due to the milk consumed by the calf. Milk yields from days 15–150 did not differ between the two groups. After separation, calves in the late-separation group moved and placed their heads outside the pen more often than early-separation calves. During the first 14 days after birth, late-separation calves gained weight at more than three times the rate of those separated early. When introduced to an unfamiliar calf at 6 weeks of age, calves from the late-separation group showed more intense social behaviour towards the unfamiliar calf than did those calves separated early. Thus, the response to separation by both cows and calves increased when calves were separated at 2 weeks rather than 1 day of age, but calves separated at the later age gained more weight and delayed separation appeared to influence the development of calf social behaviour.     

Experimental infections of Eimeria alpacae and Eimeria punoensis in llamas (Lama glama).

Four llamas (Lama glama) ranging in age from 1.5 yr to 7 yr each were inoculated orally with 10,000 (n = 2) or 50,000 (n = 2) sporulated oocysts of Eimeria alpacae (25%) and Eimeria punoensis (75%). The prepatent period for E. aplacae was 16-18 days, and it was 10 days for E. punoensis. Patent periods for E. alpacae and E. punoensis were approximately 9 days and 24 days, respectively. Although large numbers of oocysts were present in feces, no clinical sign of coccidiosis was observed. Based on ths experiment, E. alpacae and E. punoensis at the numbers given are not likely pathogenic in healthy llamas older than 1 yr.     

Group A Rotavirus as a Cause of Neonatal Calf Enteritis in Sweden

Faeces samples were collected during outbreaks of neonatal calf diarrhoea in 14 beef and dairy herds. Samples from 33 calves were taken at the onset of diarrhoea as well as from 30 calves with no signs of enteritis. No vaccines or medical treatment had previously been given. The mean age of the calves was 16.8 days (SD 8.2). The clinical evaluation of faeces consistency corresponded well to the dry matter content of the faeces (p<0.001). The samples were analyzed for rotavirus, Cryptosporidium species and Escherichia coli K99+. Group A rotavirus was detected by ELISA and RNA Polyacrylamide gel electrophoresis (RNA-PAGE) in 14/33 (43.8%) of the samples from scouring calves and 1/30 (3.7%) of the samples from non-scouring calves. The correlation between group A rotavirus and diarrhoea was statistically significant (p<0.001). No non-group A rotaviruses were found by RNA-PAGE. Cryptosporidium species were detected through demonstration of oocysts in smears from 12/63 (19.0%) of the faecal samples, but no statistically significant correlation between diarrhoea and detection of oocysts was demonstrated. Escherichia coli K99+ was not detected in any faeces sample. The clear association between group A rotavirus and diarrhoea is suggested to be due to low pathogenic load in the herds.     

Bluetongue virus serotype 8 (BTV-8) infection reduces fertility of Dutch dairy cattle and is vertically transmitted to offspring

In 2007, BTV-8 re-emerged for the second year in the Netherlands and caused morbidity and increased mortality in cattle herds. In addition, cattle farmers reported reduced fertility in their cows. For this study, fifteen herds that were not vaccinated were selected. These were matched to 10 vaccinated herds by geographic region. At the start of the study, in July 2008, all cattle in the non-vaccinated herds >1 year old were sampled. All seronegative cows entered the study program and blood samples from these cows were tested for antibodies against BTV-8 in an ELISA. Cows were sampled at intervals of three weeks and sampling was stopped once a cow tested seropositive. Sampling ceased in all remaining cows in December 2008.Newborn calves originating from infected dams or from vaccinated dams were tested by PCR for BTV-8. Fertility data were obtained from the Royal Dutch Cattle Syndicate (CRV). Multi-level generalized latent and linear models were used for analyses.In 2008, 185 (17.2%) out of 1,074 initially seronegative non-vaccinated cattle seroconverted and were assumed to be infected with BTV-8. Infected cows were 5 (95% CI: 1.9-14.3) times more likely to return for insemination within 56 days after first insemination. In addition, these cows needed 1.7 (95% CI: 1.4-2.0) times more inseminations for an assumed pregnancy, and needed 2.5 (95% CI: 2.4-2.6) times more days between first and last insemination compared to the period prior to seroconversion and compared to cows not infected by BTV-8 in 2008. No association between BTV-8 infection and the chance to abort between 100 and 260 days after last insemination was found.In total, 48 calves originating from infected cows were tested by PCR for the presence of BTV-8. Ten (20.8%) out of these 48 calves were born PCR-positive. None of 256 calves from vaccinated dams tested PCR-positive. Further, cows infected during the second half of gestation had a 15.5 times (95% CI: 1.3-190.4) higher chance of a PCR-positive newborn calf compared to cows infected in the first half of gestation. This study showed that BTV-8 has a negative effect on fertility of dairy cattle.     

A Longitudinal Study of Escherichia coli in Cows and Calves with Special Reference to the Distribution of O-antigen Types and Antibiotic Resistance

The faecal excretion of E. coli from 6 adult cows was followed over a period of 105 days. E. coli were excreted in only 23·4% of specimens and the patterns of excretion varied between animals. All isolates of E. coli were antibiotic sensitive and fell into 6 O-antigen types; very few were non-typeable. The O-types excreted by each animal, compared with those from other cows in the same house, were traced with time. A similar but less intense study was undertaken in 8 calves. In contrast E. coli was excreted from all samples and included both antibiotic sensitive and resistant strains; 37 O-types were represented. The persistence of specific O-types within each calf and their spread to other calves in the same house were studied. A comparison of the O-types in the bovine species with those isolated from man has been made.     

Immunogenicity of a single sporocyst of Eimeria maxima

Eight out of a total 40 chickens infected with single sporocysts of Eimeria maxima produced infective oocysts. These 8 chickens, when challenged with 4 X 10(5) oocysts per bird at 28 days postinfection, showed at least twice the percent average weight gain of the previously unexposed chickens, indicating that partial immunity was probably conferred by these infections. Also, these successful single sporocyst infections suggest that like E. tenella, sporozolles of E. maxima are probably sexually undifferentiated.     

Variation in Eimeria oocyst count and species composition in weanling beef heifers

Rectal fecal samples were collected daily on 10 consecutive days in November 2004 from 11 weaned beef heifers to assess daily variation in fecal oocyst count and species composition. Subsequent samples were collected from the same animals on 15 April 2005 and 9 June 2005. Oocyst numbers were determined by the modified McMaster's test, and species were identified by examination of oocysts recovered with the Wisconsin sugar flotation technique. Soil samples were collected from the heifer pasture on 8 June 2005, and oocysts were quantified and identified to species. Mean fecal oocyst counts varied little at all sampling dates ranging from 134-377 oocysts/g. Ten Eimeria spp. were identified in fecal samples collected in November and April and 11 in June. Eimeria bovis was the most common species identified at all samplings. Mean species composition showed little variation during the 10-day sampling period in November, remained similar in April, and varied slightly in June. Twelve Eimeria spp. were identified in soil samples in proportions similar to those seen in fecal samples. The results indicate that clinically normal weanling beef heifers are likely to be infected with a diverse, but relatively stable, community of Eimeria spp.     

Role of adult sheep in transmission of infection by Cryptosporidium parvum to lambs: confirmation of periparturient rise

In sheep farms, oocyst shedding by asymptomatic adult carriers is one of the mechanisms which may explain maintenance of infections by Cryptosporidium parvum between lambing periods. The objective of this work was to investigate this hypothesis and the existence of a periparturient rise in oocyst shedding. Fourteen pregnant sheep were randomly selected from two farms with a history of neonatal diarrhoea caused by C. parvum and samples were collected from the 6th week before birth until 2 weeks after birth. Faecal samples were filtered, concentrated and examined for oocysts using an indirect immunofluorescence assay. The kinetics of anti-C. parvum antibodies (IgG and IgA) were studied using an indirect enzyme-linked immunosorbent assay. All except one animal excreted C. parrum oocysts at some time during the experimental period. The percentage of animals passing oocysts increased in the first week post-partum (farm 1) and in the first week before birth (farm 2). The numbers of oocysts excreted ranged from 20-440 oocysts g(-1) of faeces. In contrast, no significant changes in the anti-C. parvum immunoglobulin levels were observed over the sampling period. Finally, a high percentage of lambs (71%) born to these ewes acquired infection in the first 2 weeks of life.     

A factor derived from adult rat and cow small intestine reduces Cryptosporidium parvum infection in infant rats

Cryptosporidium parvum is an intracellular protozoan parasite of the mammalian intestine. In rats, C. parvum infection is age related; infants are susceptible, whereas adults are resistant. The transition from susceptibility to resistance usually takes place around the age of weaning. In the present study, infant rats were orally inoculated with a preparation of intestinal scrapings taken from adult rats or cows. Infant rats received the scrapings daily from 3 to 14 days of age, were inoculated with C. parvum oocysts at 9 days of age, and killed at 15 days of age. Fecal samples and intestinal tissues were examined for the presence of C. parvum. Significantly fewer rats were infected in the groups that received intestinal scrapings compared with controls. In addition, infected rats in the treatment groups shed significantly fewer oocysts than those in the control group. Scrapings from the intestinal mucosa of adult cows were also able to protect infant rats from infection, whereas scrapings from intestines of calves were not protective. In sum, these data indicate the presence of a factor in the intestines of adult rats and cows that can transfer protection against C. parvum infection to susceptible infant rats.     

Efficacy of Monensin Against Bovine Coccidiosis in Young Holstein-Friesian Calves*

Monensin, an anticoccidial antibiotic, was incorporated into pelleted feed and given to 10-week-old Holstein-Friesian calves at 0.25 mg/kg, 1.0 mg/kg, or 2.0 mg/kg of body weight. Inoculated calves were inoculated by drenching with 500,000 sporulated oocysts of Eimeria bovis. Other calves served as inoculated or uninoculated controls. Observations were recorded on oocyst discharge in the feces, clinical signs, weight gain, food consumption, hemoglobin, packed cell volume, total serum protein, sodium and potassium content of the serum, and differential white cell counts. Calves in the inoculated control group developed severe infections, discharged large numbers of oocysts, developed clinical signs and 1 of 5 died. Uninoculated, untreated control calves were essentially free of coccidia. A few calves in the groups which received monensin developed light infections but none of them had clinical signs of coccidiosis. Calves which received the highest and the lowest dosages of monensin gained weight less rapidly than did the uninoculated controls or the animals which received monensin at 1.0 mg/kg of body weight. Inoculated control calves with severe infections had reduced food intake and a significant reduction in weight which was not regained during the experimental period. The only other significant change in any of the parameters measured was a reduction in the total serum protein of inoculated, nonmedicated control calves. The level returned to normal 5 weeks after clinical signs first appeared.     

Quantification of the crowding effect during infections with the seven Eimeria species of the domesticated fowl: its importance for experimental designs and the production of oocyst stocks.

The 'crowding effect' in avian coccidia, following administration of graded numbers of sporulated oocysts to na?ve hosts, is recognisable by two characteristics. First, increasing doses of oocysts give rise to progressively higher oocyst yields, until a level of infection is reached (the 'maximally producing dose') above which further dose increases result in progressive decreases in oocyst yields. Second, the number of oocysts produced per oocyst administered (the 'reproductive potential') tends to decrease as the oocyst dose is increased. The dose that gives the maximal reproductive potential is the 'crowding threshold' and doses exceeding this are 'crowded doses'. Graded doses of Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox or Eimeria tenella were given to chickens of the same breed, sex and age, reared on the same diet, under identical management. The two characteristics of the crowding effect were demonstrated graphically and, by interpolation, the estimated crowding thresholds were 903, < or =16, 39, < or =14, < or =16, < or =16 or 72 sporulated oocysts, respectively, for the seven Eimeria species enumerated above. This is apparently the first report of definitive experiments to quantify a crowding effect in E. brunetti, E. maxima, E. mitis, E. necatrix and E. praecox. Maximum experimental reproductive potentials were considerably lower than the theoretical reproductive potentials for all seven species. The interaction between availability of host intestinal cells and immunity contributing to the crowding effect is discussed. Standard curves obtained under specified conditions should be used to estimate appropriate infective doses for experimental designs or in vivo production of oocyst stocks. For experiments on effects of chemotherapy or immunisation on oocyst production, an infective dose lower than the crowding threshold should be used. For efficient production of laboratory or factory oocyst stocks, the maximally producing dose (which is greater than the crowding threshold), should be used.     

Calf Diseases and Mortality in Swedish Dairy Herds

A survey of the mortality and morbidity affecting calves during the first 3 months of life was carried out. Results are reported from 131 herds with altogether 5,050 calvings. These herds kept individual calf cards for all calves born. The incidences of abortions and stillborn calves were 0.6% and 3.6%, respectively. During the period 0-90 days the mortality and morbidity were 2.6% and 11.0%, respectively. The frequencies of enteritis and pneumonia in calves were 7.2% and 0.8%. Mortality and morbidity were influenced by breed, season, age of the dam and time of first colostrum. The frequencies of abortions, stillborn calves, mortality and morbidity varied considerably between herds. Herd factors influencing mortality and morbidity during different periods of time were: herd size, yield, zero-grazing, whether the calf was allowed to feed by suckling, the design of the calf pens, and previous incidence of infectious enteritis in the herd. On average, both mortality and morbidity in calves were low, though in certain herds, temporarily high frequencies were registered.     

Prevalence of enterohemorrhagic Escherichia coli O157:H7 in a survey of dairy herds.

The prevalence of Escherichia coli O157:H7 in dairy herds is poorly understood, even though young dairy animals have been reported to be a host. From February to May 1993, 662 fecal samples from 50 control herds in 14 states, and from June to August 1993, 303 fecal samples from 14 case herds in 11 states were collected for isolation of E. coli O157:H7. Case herds were those in which E. coli O157:H7 was isolated from preweaned calves in a previous U.S. Department of Agriculture study, whereas control herds from which E. coli O157:H7 had not been isolated previously were randomly selected from the same states as case herds. Among the control herds, E. coli O157:H7 was isolated from 6 of 399 calves (1.5%) that were between 24 h old and the age of weaning and from 13 of 263 calves (4.9%) that were between the ages of weaning and 4 months. Eleven of 50 control herds (22%) were positive. Among the case herds, E. coli O157:H7 was isolated from 5 of 171 calves (2.9%) that were between 24 h old and the age of weaning and from 7 of 132 calves (5.3%) that were between the ages of weaning and 4 months. Seven of 14 case herds (50%) were positive. Sixteen of 31 isolates were obtained by direct plating, with populations ranging from 10(3) to 10(5) CFU/g. Fifteen of 31 isolates were isolated by enrichment only. Nineteen of the isolates produced both verocytotoxin 1 (VT-1) and VT-2, whereas 12 produced VT-2 only.     

Attempted Cross-Transmission of Coccidia Between Sheep and Goats and Description of Eimeria ovinoidalis sp. n.

SYNOPSIS.
Attempted infection of 2 young lambs with oocysts of Eimeria christenseni from a goat was unsuccessful. Negative results were obtained also when young kids were fed oocysts of Eimeria ninakohlyakimovae from sheep. There was no difficulty in infecting lambs with the sheep coccidium resembling E. ninakohlyakimovae nor goats with the goat coccidium E. christenseni. Oocysts from the goat measured 38.4 × 26.7 m, but were easily distinguished from Eimeria ahsata from the sheep by sporocyst size and shape, and from Eimeria ovina by oocyst size. Eimeria ninakohlyakimovae -like oocysts from sheep averaged 23.0 ×18.2 m and were morphologically indistinguishable from previously reported goat coccidia.
Since no cross infections of sheep and goats could be accomplished with oocysts of Eimeria sp. characteristic of one or the other host, I concluded that sheep coccidia previously known as E. ninakohlyakimovae are distinct from morphologically similar goat coccidia and therefore constitute a separate species. Since the name E. ninakohlyakimovae was first used for coccidia from the goat, the sheep coccidium is renamed Eimeria ovinoidalis with oocyst structure and endogenous stages similar to those previously described from the sheep.     

Attempted cross-transmission of coccidia between sheep and goats and description of Eimeria ovinoidalis sp. n.

Attempted infection of 2 young lambs with oocysts of Eimeria christenseni from a goat was unsuccessful. Negative results were obtained also when young kids were fed oocysts of Eimeria ninakohlyakimovae from sheep. There was no difficulty in infecting lambs with the sheep coccidium resembling E. ninakohlyakimovae nor goats with the goat coccidium E. christenseni. Oocysts from the goat measured 38.4 X 26.7 microns, but were easily distinguished from Eimeria ahsata from the sheep by sporocyst size and shape, and from Eimeria ovina by oocyst size. Eimeria ninakohlyakimovae-like oocysts from sheep averaged 23.0 X 18.2 microns and were morphologically indistinguishable from previously reported goat coccidia. Since no cross infections of sheep and goats could be accomplished with oocysts of Eimeria sp. characteristic of one or the other host, I concluded that sheep coccidia previously known as E. ninakohlykimovae are distinct from morphologically similar goat coccidia and therefore constitute a separate species. Since the name E. ninakohlyakimovae was first used for coccidia from the goat, the sheep coccidium is renamed Eimeria ovinoidalis with oocyst structure and endogenous stages similar to those previously described from the sheep.