An examination of the prevalence of and risk factors for shedding of Cryptosporidium spp. and Giardia spp. in cows and calves from western Canadian cow-calf herds

The primary objectives of this study were to describe the prevalence and risk factors for Cryptosporidium spp. and Giardia spp. infection in cows and calves during the calving season in western Canadian cow-calf herds. Through the calving season of 2002, fresh fecal samples were collected from 560 beef cows and 605 calves in western Canada. Feces were examined for the presence of Cryptosporidium spp. and Giardia spp. using a quantitative sucrose gradient immunoflourescent antibody test. Samples were collected from mature cows on 59 farms and from calves on 100 farms. Only 1.1% (5/560) of the cows were positive for Cryptosporidium spp. whereas 3.1% (19/605) of the calves were positive. Prevalence for Giardia spp. was much higher; Giardia spp. was detected in 17.0% (95/560) of the cow and 22.6% (137/605) of calf fecal samples. Data describing herd management practices, treatment and disease history, age, gender, breed and fecal consistency were gathered to assess potential risk factors associated with shedding. The association between the risk of shedding and average precipitation from December to June and ecological region were also evaluated. Risk factors for infection with Cryptosporidium spp. in either cows or calves could not be evaluated because the multilevel model would not converge due to the relatively low prevalence of the organism in this sample. The prevalence for Giardia spp. was sufficient to explore potential risk factors in both cows and calves. No risk factors were identified for Giardia spp. in beef cows following calving. After the construction of a multivariable model, the only significant predictors for Giardia spp. presence in beef calves was dam age and calf age. Calves born to 2-year-old heifers were 2.3 (95% CI, 1.09-5.06; P = 0.031) times more likely to be shedding Giardia spp. then calves born to cows that were 4-10 years of age. Calves that were 9-18 days of age and calves that were > 18 days of age were 22.4 (95% CI, 5.88-88.18; P < 0.001) and 150 (95% CI, 39.72-603.19; P < 0.001) times more likely, respectively, to be shedding Giardia spp. than calves < or = 4 days of age.     

Prevalence of Giardia duodenalis genotypes in pre-weaned dairy calves

To determine the prevalence of Giardia genotypes in pre-weaned dairy calves, fecal samples were collected from a minimum of 18, 1-7-week-old dairy calves per farm on two farms each in the states of Vermont, New York, Pennsylvania, Maryland, Virginia, North Carolina, and Florida. Samples cleaned of fecal debris and concentrated using CsCl density gradient centrifugation were stained and examined by immunofluorescence microscopy and also subjected to PCR and gene sequence analysis. Prevalence by PCR ranged from 9% on a farm in Pennsylvania to 93% on a farm in Vermont, with an average prevalence for 407 calves on 14 farms of 40%. Gene sequence analysis of the TPI, beta-giardin and 16S rRNA genes revealed 85% of the positive samples to be Assemblage E, while 15% were Assemblage A, although the percentages of these genotypes varied greatly from farm to farm. Some farms had no Assemblage A Giardia. Thus, while a majority of the calves were infected with a genotype that is not known to be infectious for humans, calves on 7 of 14 farms did harbor Assemblage A Giardia. Calves should be considered as a potential source of human infectious cysts in the environment.     

Prevalence of species and genotypes of Cryptosporidium found in 1-2-year-old dairy cattle in the eastern United States

The prevalence of Cryptosporidium species in 1-2-year-old heifers was determined for 571 animals on 14 dairy farms in seven states on the East Coast of the United States. A fecal specimen collected directly from each heifer was processed to concentrate oocysts that were then examined by polymerase chain reaction (PCR). For every PCR-positive specimen the 18S rRNA gene of Cryptosporidium was sequenced. Cryptosporidium was identified by PCR from heifers on 13 of 14 farms. On all except four farms groups of heifers were housed in a barn or in large covered pens. Others were pastured. From many of the same farms an earlier study reported that 41% of 393 pre-weaned calves and 26.2% of 447 post-weaned calves were infected. In the present study, 11.9% of 571 heifers were infected with Cryptosporidium, 0.7% with Cryptosporidium parvum, the zoonotic species. Of 68 PCR-positive specimens characterized by gene sequencing 1, 4, 10, 24, and 29 calves were infected with Cryptosporidium suis, Cryptosporidium parvum, Cryptosporidium deer-like genotype, Cryptosporidium bovis, and Cryptosporidium andersoni, respectively. These findings demonstrate a lower prevalence of infection in 1-2-year-old dairy cattle than in younger cattle as well as a change in the diversity of species present. Consequently, the risk of humans acquiring infection with C. parvum from exposure to feces from yearling and older cattle appears much lower than from exposure to pre-weaned calves.     

Molecular characterization of Cryptosporidium and Giardia in pre-weaned calves in Western Australia and New South Wales

A total of 364 fecal specimens from randomly selected pre-weaned calves, aged up to 4 months, from 5 different farms in the south of Western Australia and 1 farm from New South Wales were screened for the presence of Cryptosporidium and Giardia using PCR. There were substantial differences in prevalence between the farms and the overall prevalence was 22.3% (81/364) and 26.9% (98/364) respectively for Cryptosporidium and Giardia. For Cryptosporidium, 70 positives were identified at the 18S locus. At a unique diagnostic locus, an additional 12 C. parvum positives were identified. Sequence analysis at the 18S ribosomal RNA locus was successful for 59 of the 70 positive isolates; of these 14 were C. parvum, 28 were C. bovis, 15 were C. ryanae, 1 was pig genotype II and 1 was a mixed C. ryanae/C. parvum infection. Sub-typing analysis at the glycoprotein 60 (gp60) locus for 24 C. parvum isolates identified all as IIa; 17 were A17G2R1, 1 was A18G3R1 and 6 were A20G3R1. For Giardia, 75 positives were identified at the 18S locus and an additional 23 positives were identified at the gdh locus. The majority of the isolates sequenced were assemblage E, however assemblage A and B and mixed A and E and A, B and E infections as well as the quenda genotype were identified. The findings of the present study indicate that pre-weaned calves are not an important source of zoonotic Giardia species in Australia but may be an important source of zoonotic Cryptosporidium.     

Prevalence and age-related variation of Cryptosporidium species and genotypes in dairy calves

Fifteen dairy farms in seven states on the east coast of the US were each visited on two consecutive years to determinate the prevalence of Cryptosporidium species in pre-weaned (5 days to 2 months) and post-weaned calves (3-11 months), respectively. After each of 971 fecal specimens collected directly from each calf was sieved and subjected to density gradient centrifugation to remove debris and concentrate oocysts, specimens were examined by immunofluorescence microscopy, and polymerase chain reaction (PCR). For all PCR-positive specimens the 18S rRNA gene of Cryptosporidium was sequenced. Cryptosporidium was identified from all farms. Types of housing appeared to have no influence with regard to prevalence of infection. Of 971 calves, 345 were infected with Cryptosporidium (35.5%), but more pre-weaned calves (253 of 503; 50.3%) than post-weaned calves (92 of 468; 19.7%) were found to be infected. A total of 278 PCR-positive specimens characterized by gene sequencing revealed Cryptosporidium parvum, Cryptosporidium andersoni, and two unnamed Cryptosporidium genotypes Bovine B (AY120911) and deer-like genotype (AY120910). The prevalence of these Cryptosporidium species and genotypes appeared to be age related between pre- and post-weaned calves. C. parvum, the only zoonotic species/genotype, constituted 85% of the Cryptosporidium infections in pre-weaned calves but only 1% of the Cryptosporidium infections in post-weaned calves. These findings clearly demonstrate that earlier reports on the presence and prevalence of C. parvum in post-weaned cattle that were based solely on oocyst morphology must be reassessed using molecular methods to validate species and genotype. This finding also indicates that persons handling or otherwise exposed to calves under 2 months of age are at greater risk of zoonotic infection from Cryptosporidium than the risk of infection from exposure to older calves.     

Prevalence and genotypes of Giardia duodenalis in post-weaned dairy calves

To determine the prevalence of Giardia genotypes in post-weaned dairy calves, fecal specimens were collected from 3 to 11-month-old dairy calves per farm on two farms in Vermont, New York, Pennsylvania, Maryland, Virginia, North Carolina, and Florida. Specimens cleaned of fecal debris and concentrated using CsCl density gradient centrifugation were stained and examined by immunofluorescence microscopy and also subjected to PCR and DNA sequence analysis. Overall, PCR provided more sensitive detection than IFA. Prevalence of Giardia infection, as detected by PCR ranged from 20% on NC-2 to 81% on VT-2, with an overall prevalence of 52% (237 positive samples out of 456 total). DNA sequence analysis of the 16S rRNA gene revealed 87% of the 237 Giardia isolates were Assemblage E, and 13% were Assemblage A although the prevalence of these genotypes varied greatly from farm to farm, with five farms having no Assemblage A Giardia. Therefore, Assemblage E was present in 45% of all animals tested and Assemblage A was present in 7% of the animals. Thus, while many of the calves were infected with a genotype that is not known to be infectious for humans, post-weaned calves on nine of 14 farms did harbor Assemblage A Giardia. Therefore calves should be considered as a potential source of human infectious cysts in the environment, with some farms representing a much higher risk than others.     

Prevalence of Giardia and Cryptosporidium in beef cows in southern Ontario and in beef calves in southern British Columbia

In 1998 and 1999, fecal samples were collected from 669 beef cows on 39 farms located within 10 counties of Ontario. Overall prevalences of Giardia, Cryptosporidium muris, and Cryptosporidium parvum in cows were 8.7%, 10.6%, and 18.4%, respectively. Of the 39 farms sampled, Giardia was detected on 64%, Cr. muris on 72%, and Cr. parvum on 90%. Cryptosporidium parvum was detected in 28% of the cows in 1998 and in 5.2% in 1999. Differences between the 2 y were attributed to sampling during calving in 1998 and during gestation in 1999. In 1998, Giardia, Cr. muris, and Cr. parvum were detected in herds provided with municipal water. In 1998, 193 calves were sampled from 10 farms, representing 4 watersheds, in British Columbia. Thirty-six percent of the calves exhibited signs of diarrhea. Overall prevalences of Giardia and Cryptosporidium spp. in calves were 36% and 13%, respectively. There was evidence that calves with Giardia were more likely to develop scours. Restricting cattle from surface water during periods of high shedding may reduce watershed contamination.     

A cross-sectional study of the prevalence of foot lesions in post-weaning pigs and risks associated with floor type on commercial farms in England

We carried out a cross-sectional study during 2003 and 2004 to establish the prevalence and risk factors associated with floor type for commonly observed foot lesions in pigs aged 6, 8 and 14 weeks. The overall prevalence of foot lesions was 39.6% in 2283 pigs from 90 representative pig farms in England. The most prevalent lesions were heel/sole bruising (7.1%), heel/sole erosion (10.8%), heel flaps (8.4%) and toe erosion (11.6%). Pigs were kept on either solid (41%), partly slatted (28%) or fully slatted (31%) floors. Of the 104 pens with a solid floor, 26% of pens were outside with straw bedding on a soil base, 33% were indoors with deep bedding on solid concrete, 25% were partly deeply bedded on solid concrete and 16% were sparsely bedded on solid concrete. Only six of the pens with partly slatted floors were bedded.Multilevel logistic-regression models were built using data from 100 farms to examine the risks for individual foot lesions with prevalences >5%. The prevalence of toe erosions was positively associated with deep bedding, whereas deep bedding and soil floors were negatively associated with the prevalence of heel/sole erosions. Heel flaps and heel/sole bruising were both associated with slatted floors, possibly indicating a common aetiology. The greatest reduction in prevalence of all these lesions, from AFp calculations, would be achieved by moving pigs from slatted floors onto solid floors.     

Prevalence and genotyping of Giardia duodenalis from beef calves in Alberta,Canada

Giardia infections in domestic cattle has come under increasing scrutiny owing to the potential contamination of surface and ground waters through manure distribution on fields and pasture runoff. The objective of the study was to determine the prevalence and genotypes of Giardia duodenalis in beef calves in major beef cow calf farms in Alberta, Canada. Fecal samples were collected from beef calves aged 2-10 weeks at nine farms in Alberta. Samples were examined for the presence of G. duodenalis cysts by immunofluorescent staining. Giardia cysts were found in 168 of the 495 fecal samples examined, with prevalence ranging from 7 to 60% among farms. Genotypic analysis of positive isolates utilizing PCR and sequencing of a 292 bp fragment of the 16S-rRNA locus, revealed the hoofed livestock genotype in 41 of the 42 isolates. One isolate was identical to the Assemblage A genotype. The results of this study demonstrate that beef calves in this area are primarily infected with the livestock genotype which is thought to be specific to artiodactyl hosts and non-infective to humans. This suggests that the Giardia carried by beef cattle may be a minimal zoonotic threat.     

Prevalence of Giardia and Cryptosporidium spp in calves from a region in New Zealand experiencing intensification of dairying

AIM: To investigate the prevalence of Giardia and Cryptosporidium spp in calves born during two spring-calving seasons in a rapidly intensifying dairying region in the South Island; to evaluate potential correlations between the prevalence of the organism and age, characteristics of faeces, and animal-housing practices; and to compare the results with those from established dairying regions in the North Island. METHODS: A longitudinal study was conducted in 2005 and 2006 on 10 dairy farms located in the Otago region, South Island, New Zealand. A total of 1,190 faecal samples were collected from calves 1-7 weeks old. Direct immunofluorescent microscopy was used to screen the faecal samples for Giardia cysts and Cryptosporidium oocysts. The prevalence of Giardia and Cryptosporidium spp detected in calves in Otago was compared with that previously measured in calves from dairying regions in the Waikato and Manawatu, in the North Island . RESULTS: On average, Giardia and Cryptosporidium spp were detected in 31% and 2.6% of all samples, respectively. The prevalence of Giardia spp cysts in faeces was higher in calves >or=3 weeks of age in 2005 (por=2 weeks of age in 2006 (p=0.07) than in younger calves. No age-related pattern was observed for Cryptosporidium spp in either year. No correlations were evident between characteristics of faeces or animal housing practices and the prevalence of either organism, which did not differ between the two dairy farming regions. CONCLUSIONS: Prevalence rates of Giardia and Cryptosporidium spp in calves 1-7 weeks old did not differ between the two geographical regions, nor did the regions' distinct climate conditions appear to influence the prevalence of either pathogen. Considering data from both years together, the presence of Giardia spp cysts in faeces appeared to increase in the first week or two after birth, so that, on average, 30-40% of animals from 3-6 weeks of age were affected. CLINICAL RELEVANCE: This is the first study to report the prevalence of Giardia and Cryptosporidium spp in dairy calves in the South Island of New Zealand.     

Age-related and housing-dependence of Cryptosporidium infection of calves from dairy and beef herds in South Bohemia, Czech Republic

Data of the prevalence, age-related and housing-dependence of naturally acquired cryptosporidiosis on 11 dairy and 11 beef farms in South Bohemia (Czech Republic) were collected. The farms were visited over four consecutive years (from 2002 to 2005). The prevalence of Cryptosporidium in pre-weaned (animals until second month of age) and post-weaned (animals from the third month of age) calves was determined. A total of 7001 faecal samples were collected, concentrated by Sheather's floatation method and stained by aniline-carbol-methyl violet. All samples were examined by light microscopy. Cryptosporidium parvum and C. andersoni oocysts were differentiated on morphological criteria. Of the 7021 specimens, 1814 (25.8%) were positive for Cryptosporidium oocysts; 561 samples (8%) for C. parvum and 1253 (17.8%) for C. andersoni. Pre-weaned dairy calves had higher infection levels of C. parvum than pre-weaned beef calves. The prevalence of C. parvum ranged from 1.4 to 56.5% on dairy farms. Only three cases of C. parvum oocysts shedding in pre-weaned calves on beef farms were found. Only one case of C. andersoni infection in pre-weaned calves was detected and no infections of C. parvum in post-weaned calves were found. The prevalence of C. andersoni reached 35.5% on dairy farms and 61.7% on beef farms. Calves that were on pasture all year long, had a lower probability of C. andersoni infection than those calves kept in a cowshed during the winter season.     

Prevalence and infection pattern of naturally acquired giardiasis and cryptosporidiosis in range beef calves and their dams

The prevalence and infection pattern of naturally acquired giardiasis and cryptosporidiosis in 20 ranch raised beef calves and their dams from birth to weaning was determined. Rectal fecal samples were collected from calves at 3 days of age and weekly thereafter; cows' fecal samples were collected at the time of calving, 1 week later and four times during the summer grazing period. Blood samples were collected from the calves at 3 days of age to determine IgG(1) concentrations. Giardia lamblia cysts were shed by all 20 calves (100%) at some date during the duration of the study. However, only one calf (5%) shed Cryptosporidium parvum on two sample dates during the trial. Giardia cysts were first detected at 3.9+/-1.37 weeks of age with a range of 2-7 weeks of age. The geometric mean number of Giardia cysts in the calf feces increased from none at 1 week of age to a maximum of 2230 cysts/g of feces at 5 weeks of age and then decreased to 2 cysts/g at 25-27 weeks of age. Infection rate of calves shedding Giardia cysts peaked at 85% at 5 weeks of age and then decreased to 21% at 25-27 weeks of age. Giardia cysts, shed by calves peaked 1 week after initial shedding and decreased (P<0.05) for the remainder of the trial with the exception of week 3. There was a lower (P<0.05) percentage of calves shedding Giardia cysts weeks 3-10 and 15-25 compared to when shedding was first detected. All calves had complete or partial transfer of passive immunity as measured by IgG(1) levels. The rate of infection (15%) and the geometric mean number of Giardia cysts in the cows' feces (38.49 cysts/g) numerically increased at 1 week post-calving compared to levels at calving. The rate of infection (40%) numerically increased and the geometric mean number of Cryptosporidium andersoni oocysts in the cow feces (37.48 oocysts/g) increased (P<0.05) at 1 week post-calving and decreased to 0 at 13-16 weeks post-calving. This study is the first to document the cumulative prevalence and infection patterns of Giardia and Cryptosporidium in beef cattle under ranch conditions.     

The potential for zoonotic transmission of Giardia duodenalis and Cryptosporidium spp. from beef and dairy cattle in Ontario, Canada

The objective of this study was to compare the occurrence and the genotypes and species of Giardia duodenalis and Cryptosporidium spp. in beef and dairy cattle from farms in the Regional Municipality of Waterloo, Ontario, in an effort to determine the potential for zoonotic transmission from these animals. Pooled manure samples were collected from 45 dairy cattle farms and 30 beef cattle farms. The presence of Giardia cysts and Cryptosporidium oocysts was determined by immunofluorescence microscopy, while nested-PCR and DNA sequencing were used to determine genotypes and species. The overall farm prevalence was very high for both Giardia and Cryptosporidium, and was similar for dairy cattle farms (96 and 64%, respectively) and beef cattle farms (97 and 63%, respectively). However, on dairy cattle farms, G. duodenalis and Cryptosporidium spp. were detected in 44% and 6% of total pooled pen manure samples, respectively, with the occurrence of both parasites being generally higher in calves than in older animals. Most Giardia isolates were identified as either the host-adapted genotype G. duodenalis Assemblage E or the zoonotic Assemblage B. Cryptosporidium parvum and Cryptosporidium andersoni were the most frequently identified species in dairy cattle, while the non-zoonotic species Cryptosporidium ryanae and Cryptosporidium bovis were also found. On beef cattle farms, 72% and 27% of the total pooled pen manure samples were positive for Giardia and Cryptosporidium, respectively, with no obvious correlation with age. All Giardia isolates in beef cattle were identified as G. duodenalis Assemblage E, while all Cryptosporidium isolates were identified by sequence analysis as C. andersoni, although microscopic analyses, and subsequent restriction fragment length polymorphism analyses, indicated that other Cryptosporidium species were also present. The results of this study indicate that although Giardia and Cryptosporidium were identified in a higher overall percentage of the pooled beef cattle manure samples than in dairy cattle, firmly established zoonotic genotypes and species were much more common in dairy cattle than in beef cattle in this region. Dairy cattle, and especially dairy calves, may, therefore, pose a greater risk of infection to humans than beef cattle. However, these results may also provide evidence of potential zooanthroponotic transmission (human to animal).     

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.     

The prevalence of bovine viral diarrhea virus infection in a population of feedlot calves in western Canada.

The prevalence of bovine viral diarrhea virus (BVDV) infection was examined in a population of 5129 recently weaned steer calves entering a large feedlot in central Saskatchewan from September to December 1991. Serum samples were collected within 24 h of arrival at the feedlot from every fifth calf processed and again 96 d postarrival. A microtiter virus isolation test was used to determine the prevalence of calves viremic with BVDV on entry to the feedlot. An enzyme-linked immunosorbent assay (ELISA) which detects antibody against glycoprotein 53 of the BVDV was used on paired sera to determine the seroconversion risk during the first 96 d in the feedlot. A virus neutralization (VN) test for BVDV was conducted on a sub-sample of paired sera to measure agreement in determination of seroconversion risk with the ELISA. A polymerase chain reaction (PCR) test which detects BVDV was used to determine if cattle were acutely viremic when treated for disease. The estimated prevalence of persistently infected calves in this population was < 0.1%. The seroconversion risk for BVDV was 27% (236/864) according to the ELISA and it varied from 0 to 63% among the 20 pens sampled. According to the VN test, the seroconversion risk for BVDV was 40% (132/327) and it varied from 0 to 100% among the 11 pens tested. The agreement between the ELISA and VN tests in seroconversion risk to BVDV was very poor (kappa = 0.15 +/- 0.039 SE). The prevalence of acute viremia in calves treated at the feedlot hospital was low at 4% (6/149).(ABSTRACT TRUNCATED AT 250 WORDS)     

The occurrence of Cryptosporidium parvum, Campylobacter and Salmonella in newborn dairy calves in the Manawatu region of New Zealand

AIM: To determine the occurrence of Cryptosporidium parvum oocysts, Campylobacter spp and Salmonella spp in faecal samples taken from newborn dairy calves on 24 dairy farms in the Manawatu region of New Zealand. METHODS: A cross-sectional study was conducted during the 2002 calving season. Faecal samples were collected from 185 newborn calves from a convenience sample of 24 dairy farms. The samples were tested microscopically for the presence of C. parvum oocysts, and bacteriologically for the presence of Campylobacter spp and Salmonella spp. RESULTS: Infections with C. parvum were identified in 33/156 (21.2%) calves from 10 farms. More than 10(6) oocysts/g (OPG) faeces were detected in calves from four farms. Campylobacter spp were isolated from 58/161 (36%) calves from 18 farms; in particular, C. jejuni subsp jejuni was isolated from 11/161 (6.8%) calves from seven farms. Salmonellae were not detected. CONCLUSIONS: Despite the short and concentrated calving pattern and the long interval between calving seasons characterising most dairy farms in New Zealand, C. parvum is widespread among calves. Campylobacter spp, especially C. jejuni, rapidly colonise the intestinal tract of newborn calves. RELEVANCE: This study provided an estimate of the ecological impact of newborn dairy calves with regard to the potentially zoonotic enteric pathogens most frequently isolated from human gastrointestinal infections in New Zealand.     

Dairy calf management,morbidity and mortality in Ontario Holstein herds. IV. Association of management with mortality

Associations between heifer calf management and mortality were studied on 104 randomly selected Holstein dairy farms in southwestern Ontario between October 1980 and July 1983. At the farm level, data were stratified by season, with two six-month seasons (winter and summer) per year. The odds of farms with particular management strategies having above-median morbidity were calculated. At the individual calf level, the odds of a calf being treated, controlling for farm of origin and month of birth, were calculated for different management practices.Larger farms had significantly greater odds of experiencing mortality than smaller farms in both winter and summer. Farms which had policies of attending calvings and ensuring that calves received their first colostrum had significantly lower odds of experiencing winter mortality than farms which did not have these policies. Farms which housed calves in hutches had significantly lower odds, and those which housed calves in group pens had significantly higher odds, of experiencing summer mortality, than farms which used individual indoor calf-pens. A policy of teat removal between four weeks of age and weaning was associated with increased odds of summer mortality.At the individual calf level, calving ease, sire, navel treatment, assistance at first colostrum feeding, administration of vitamins A, D and E and anti-scour vaccines to the pregnant dam, and place of calving, were all associated with significantly altered odds of dying. However, several interactions entered the statistical models, and the effects of those management practices were not all straightforward.     

Dairy calf mortality rate: influence of management and housing factors on calf mortality rate in Tulare County, California.

Data on calf mortality, calving site, calf-rearing facilities, and calf-management procedures were collected from 16 dairy farms in Tulare County, California. Discriminant analyses were used to test if any significant differences in these factors existed between farms with higher than average and farms with lower than average death losses. The average mortality rate over a period of at least 2 years on individual farms varied from a low of 3.5 +/- 1.1% to a high of 30.6 +/- 3.1%. Calf management personnel was the only factor significantly related to the mortality rate, with considerably fewer death losses on farms where the owner managed the calves than on farms where employees performed these duties. In general, other factor categories relating to size of the cow herd, calving site, and calf housing were not related significantly to calf deaths. The average number of heifer calves born each year on individual farms was increasing year by year, and on some farms, there seemed to be a concomitant increase in death losses. This, together with the tendency toward greater number of deaths on the larger owner-managed farms, indicated that calf care was diluted under these conditions.     

Control of bovine coccidiosis with monensin: in nonresistant newborn calves

Newborn Holstein male calves were purchased within 3 days after birth and were removed from the local farms to the Dixon Springs Agricultural Research Center. They were hand-fed for 7 weeks and then weaned to a prepared feed. Eight groups, each of 4 calves, were housed in separate pens. In each of 4 pens (pens 2 to 5), 1 calf was inoculated with sporulated oocysts of Eimeria bovis (and was not medicated); 1 calf was inoculated and given feed with added monensin at the dosage level of 10 g/906 kg of feed; and 2 calves were inoculated and given medicated feed with added monensin at the dosage level of 20 g/906 kg or 30 g/906 kg. In the 4 other pens (6 to 9), the calves were inoculated with E zuernii and otherwise were given feed without or with added monensin as in pens 2 through 5. Another group of 5 calves (all kept in 1 pen), served as noninoculated, nonmedicated controls. At 14 days after inoculations with E bovis, the single calves in each of the 4 pens that were given the nonmedicated feed began to show clinical signs of coccidiosis and discharged increasing numbers of oocysts. The other inoculated calves (given monensin) had fewer clinical signs and discharged fewer oocysts in the feces as the level of medication in the feed increased. The calves inoculated with E zuernii developed only moderately severe infections when compared with those inoculated with E bovis. Inoculated (with E bovis) nonmedicated calves had severe reductions in feed consumption and weight, and 3 of 4 died.(ABSTRACT TRUNCATED AT 250 WORDS)