Publications

culling practices of ontario cow-calf producers.	this study describes the distribution of herd culling rates for 123 ontario cow-calf herds maintaining individual animal records. associations between culling and factors at both the individual and herd level were examined. in addition, the relative importance of individual animal and herd level influences on culling were investigated. the following individual cow culling risk factors: nonpregnancy, age, weaning weight index, calf outcome, abortion, prolapsed vagina, prolapsed uterus, calving in ...	1992	1586894
patterns of stillbirth and dystocia in ontario cow-calf herds.	the association between a number of individual animal and herd level factors and calving problems in beef cows and heifers were examined. data were from the 1987 calving season for a subset of 123 herds which maintained individual-animal records, from a sample of 180 randomly selected ontario cow-calf herds. the median herd dystocia rate was 5.8% and 24.4% of herds had no dystocias. the median herd stillbirth rate was 2.8%, and 33.3% of herds had no stillbirths. dystocias and stillbirths were mu ...	1992	1586893
a short incubation serum neutralization test for bovine viral diarrhea virus.	a three day serum neutralization (sn) test for the detection of antibodies to bovine viral diarrhea virus (bvdv), which is an improvement on the existing five day test, is described. the improved test results in a more rapid viral cytopathic effect and utilizes madin darby kidney (mdbk) cells, and horse serum as a medium supplement. a comparison of tests utilizing the nadl and the singer strains of bvdv and the use of either secondary bovine kidney cells with calf serum (bkcs) or continuous mdbk ...	1992	1317246
interaction of age and month of calving with year of calving for production traits of ontario holsteins.	production records of 835,789 ontario holsteins calving between 1958 and 1990 were used to determine the presence of an interaction of the age and month of calving of cows with the year of calving for production of milk and fat and fat percentage. an animal model was employed including the effects of herd-year-season of calving, interaction of age and month of calving with year of calving, animal additive genetic effects, and permanent environmental effects. tests for interactions of age with ye ...	1993	8132887
highly presumptive identification of bacterial isolates associated with the recent canada-wide mastitis epizootic as nocardia farcinica.	a highly presumptive identification of nocardia farcinica was made of 47 bacterial isolates. fifteen isolates from alberta, 9 from ontario, and 2 each from new brunswick, newfoundland, and nova scotia were from clinical cases involved in the canadian mastitis epizootic. seventeen additional isolates from alberta were recovered from farm milk bulk tanks from herds found to have cows involved in the epizootic. all isolates were shown by high-performance liquid chromatography to possess mycolic aci ...	1993	8364799
dynamics and regulation of bulk milk somatic cell counts.	somatic cell count (scc) in milk is inversely related to dairy cow productivity and milk quality. in an effort to improve product quality, and indirectly farm productivity, regulatory limits on somatic cell counts have been established by many of the major dairy producing countries. the purpose of this paper was to assess the impact of regulations on bulk milk somatic cell counts in ontario and to assist producers in meeting regulatory limits through development of prediction models. through the ...	1993	8490807
a serological survey for bovine immunodeficiency-like virus in ontario dairy cattle and associations between test results, production records and management practices.	a chemiluminescence western blot analysis (wba) for detecting antibovine immunodeficiency-like virus (biv) antibodies, had good repeatability. the test was subsequently applied to a bank of serum samples from 928 adult cows from 265 herds in ontario; the number of cows sampled within each herd ranged from 1 to 13. the overall prevalence of anti-biv antibodies among cows was 5.5% with a 95% confidence interval of 4.2% to 7.2%. in contrast, 18.1% of herds had at least one reactor among cows tested ...	1994	8143251
production indices, calf health and mortality on seven red veal farms in ontario.	production, morbidity, mortality and culling were investigated on seven commercial red veal farms in ontario. the total number of calves included in the study group was 2251. the mean exit weight of marketed calves was 291 kg, with an average daily gain of 1.52 kg/day over the entire production period. the percentage of calves receiving one or more treatment days was 55%, with an average number of individual treatment days per treated calf of 3.9. an increasing number of treatment days, particul ...	1994	7954122
cysticercus bovis in cattle in two beef feedlots in southern ontario.		1994	7866963
production practices, calf health and mortality on six white veal farms in ontario.	a group of 4863 white veal calves reared on six commercial white veal farms in ontario were followed through production to describe calf characteristics and production levels. patterns of morbidity, mortality, and culling were investigated at the farm, room and individual level. the majority of the calves were male holsteins, with approximately half originating from ontario. the mean average daily gain for shipped calves over the entire production period was 1.1 kg/day (se = 0.002). the overall ...	1994	7954121
forensic application of repetitive dna markers to the species identification of animal tissues.	highly repetitive dna markers have been used for determining the species origin of animal tissues in cases of illegal commercialization and poaching of game animals. this approach has been used in cases involving white-tailed deer (odocoileus virginianus), moose (alces alces) and black bear (ursus americanus). digesting the dna with various restriction enzymes, agarose electrophoresis and staining with ethidium bromide revealed unique banding patterns for each species. these patterns have been u ...	1994	8195749
like father, like son.		1994	7730114
evidence of direct transmission of escherichia coli o157:h7 infection between calves and a human--ontario.		1994	8038753
bovine viral diarrhea in a dairy herd.		1995	7757928
prevalence of bovine parvovirus infection in ontario dairy cattle.	studies were conducted to determine prevalence and dynamics of bovine parvovirus (bpv) infection. dairy cows from 29 randomly selected herds in southwestern ontario were tested twice, one year apart, for the presence of hemagglutination inhibition (hi) antibodies against bpv. fifty-one percent of 1141 cows tested had bpv-hi titers > 1:32. one year later, the seroprevalence was 83% in 1131 cows from the same farms. the herd mean seroprevalence was 49% and 86% for the year-1 and year-2 samples, re ...	1995	7648531
mechanobullous disease in a belgian foal in eastern ontario.		1995	7497429
a serological survey of bovine syncytial virus in ontario: associations with bovine leukemia and immunodeficiency-like viruses, production records, and management practices.	of the 920 cows tested, 56.7% showed antiretroviral serological reactivity. prevalence rates (95% confidence interval) of antiretroviral antibodies among individual dairy cows in ontario were: biv 5.5% (4.0-7.0), blv 25.7% (22.9-28.6), and bsv 39.6% (36.4-42.8). the following percentages of cows showed serological reactivity against the specified retroviruses: biv 2.3%, blv 14.0%, bsv 27.5%, biv and bsv 1.3%, biv and blv 0.9%, blv and bsv 9.9%, biv and blv and bsv 0.9%. these rates of sero-posit ...	1995	8548688
economic benefits of reducing somatic cell count under the milk quality program of ontario.	an empirical stochastic model for monthly bulk milk scc was used to determine the impact of bulk milk ssc on the probability and cost of penalties under the milk quality program of ontario, canada. under this program, milk price is reduced by $1 (canadian)/hl each time bulk milk scc exceeds 500,000 cells/ml three times in a 4-mo period. the model included herd average bulk milk scc, effects of season, five autoregressive terms for bulk milk scc in previous months, and a random variable with a st ...	1996	8708100
trends in bovine abortions submitted to the ontario ministry of agriculture, food and rural affairs, 1993-1995.		1996	8705972
bovine anthrax in eastern ontario.		1996	9111696
update on bovine virus diarrhea in ontario.		1996	8681292
evaluation of a bulk-milk elisa test for the classification of herd-level bovine leukemia virus status.	the results of a commercial bulk-milk enzyme-linked immunosorbent assay (elisa) test for herd-level bovine leukemia virus (blv) status were compared to results obtained from individual agar-gel immunodiffussion (agid) testing on sampled cattle. a positive herd was defined as a herd having one or more agid-positive animals. the estimated true herd status was based on the sensitivity and specificity of the agid test and the number of cattle sampled per herd. ninety-seven herds were used, with a me ...	1997	9234446
associations between farm management practices, productivity, and bovine leukemia virus infection in ontario dairy herds.	the objective of this study was to investigate the associations between herd-level bovine leukemia virus (blv) status and herd-level management and production variables. the study population consisted of 1330 cows sampled from 102 ontario dairy herds. the individual-cow prevalence of blv infection in the population (based on agid testing) was 23%, with 69.6% of herds having one or more positive animals. the herd-level explanatory variables were divided into two datasets containing winter housing ...	1997	9234445
use of test day milk fat and milk protein to detect subclinical ketosis in dairy cattle in ontario.	serum beta-hydroxybutyrate (bhb) levels were determined for 1333 dairy cows in various stages of lactation and parity on 93 dairy farms in ontario. the data were collected in a cross-sectional manner, as part of the 1992 ontario dairy monitoring and analysis program. the median serum bhb was 536 mumol/l for all cows, with a range of 0 to 5801 mumol/l. when subclinical ketosis was defined as a serum bhb level of 1200 mumol/l or higher, the prevalence of ketosis for cows in early lactation (< 65 d ...	1997	9360791
persistence of escherichia coli o157:h7 in dairy cattle and the dairy farm environment.	the persistence of escherichia coli o157:h7 in cattle and the farm environment was investigated on eight ontario dairy farms positive for e. coli o157:h7 in a longitudinal study commenced one year previously. faecal samples from cows, calves, humans, cats, rodents, wild birds, a composite fly sample and numerous composite and individual environmental samples were cultured and tested for verotoxin-producing e. coli (vtec). vtec isolates were serotyped and e. coli o157:h7 isolates were phage typed ...	1997	9363025
associations between winter herd management factors and milk protein yield in ontario dairy herds.	a questionnaire was used to investigate associations between farm management practices in winter and milk protein yield. the questionnaire was completed by 500 dairy producers in ontario, canada in march 1994. a high positive correlation (0.96) existed between herd mean for protein yield per day per cow and herd mean for milk yield per day per cow. therefore, most management practices that were associated with the farm mean for protein yield per day per cow were also associated with the farm mea ...	1997	9406070
clinical mastitis in dairy cattle in ontario: frequency of occurrence and bacteriological isolates.	the objective of this study was to describe the frequency of occurrence of clinical mastitis in dairy herds in ontario. the study group consisted of 65 dairy farms involved in a 2-year observational study, which included recording all clinical mastitis cases and milk sampling of quarters with clinical mastitis. lactational incidence risks of 9.8% for abnormal milk only, 8.2% for abnormal milk with a hard or swollen udder, and 4.4% for abnormal milk plus systemic signs of illness related to masti ...	1998	9442950
effect of duration of fasting and a short-term high-roughage ration on the concentration of escherichia coli biotype 1 in cattle feces.	a field trial using cattle from a commercial feedlot was conducted to quantify the effect of duration of fasting and a temporary change in ration on the concentration of escherichia coli biotype 1 in feces. a nested hierarchical design with repeated measures through time was used. two groups of 20 british x european breed beef steers having reached slaughter weight (mean live weight 685 kg; sd 50 kg) were fed entirely on a high-energy ration typical of that used in the ontario beef finishing ind ...	1998	9709222
verocytotoxigenic escherichia coli infection in dairy farm families.		1998	9553280
factors affecting reproductive performance in ontario dairy herds.	data were collected on reproductive, health and production events in 45 dairy herds in southwestern and eastern ontario, canada, from july 1990 to july 1993. mean and median days in milk at first estrus, at first service, and at conception were 85.1 and 83.9, 94.0 and 88.9, and 126.3 and 115.5 d, respectively. the mean estrus detection rate was 48.3%, with a minimum of 28.4% and a maximum of 64.2%. the mean overall conception rate was 46.7%, with a minimum of 29.8% and a maximum of 70.7%. the mo ...	1998	10734437
retrospective study of toxic metal analyses requested at a veterinary diagnostic toxicology laboratory in ontario (1990-1995).	during the 5-year period from january 1, 1990, to december 31, 1995, 887 diagnoses of metal toxicosis in domestic animals and wild birds were documented at the veterinary laboratory services branch of the ontario ministry of agriculture, food and rural affairs. most of these cases involved cattle, sheep, and birds. lead toxicosis was diagnosed in 399 cases, copper toxicosis in 387, zinc toxicosis in 49, mercury toxicosis in 44, iron toxicosis in 4, and selenium in 4 cases. trends in species affe ...	1998	9442951
severe acute bovine viral diarrhea in ontario, 1993-1995.	in 1993, noncytopathic bovine viral diarrhea virus (bvdv) strains with enhanced virulence caused unprecedented outbreaks of severe acute bovine viral diarrhea (bvd) in dairy, beef, and veal herds in ontario (canada). fever, pneumonia, diarrhea, and sudden death occurred in all age groups of cattle. abortions often occurred in pregnant animals. gross lesions in the alimentary tract were similar to those associated with mucosal disease, especially in animals >6 months of age. cattle of all age gro ...	1998	9526857
escherichia coli o157:h7 diarrhoea associated with well water and infected cattle on an ontario farm.	a 16-month old female child living on an ontario dairy farm was taken to hospital suffering from bloody diarrhoea. escherichia coli o157:h7 was isolated from her stool. initial tests of well water samples were negative for e. coli by standard methods but culture of selected coliform colonies on sorbitol-macconkey agar led to isolation of e. coli o157:h7. e. coli o157:h7 was also isolated from 63% of cattle on the farm. the e. coli o157:h7 isolates from the child, the water and the cattle were ph ...	1998	9528813
an evaluation of protein/fat ratio in first dhi test milk for prediction of subsequent displaced abomasum in dairy cows.	first dhi test milk that was sampled prior to displaced abomasum (da) diagnosis was used to evaluate milk protein/fat ratio (pfr) for prediction of subsequent da in dairy cows. odds ratio, sensitivity, specificity, and likelihood ratio were determined. twenty-seven da cases were matched to 3 controls per case by herd and calving date. milk was tested at a median of 19 d after calving, which was 8 d prior to the median time of da diagnosis. adjusted for parity and days in milk, a protein/fat rati ...	1998	9553715
detection of bovine torovirus in fecal specimens of calves with diarrhea from ontario farms.	breda virus (brv), a member of the genus torovirus, is an established etiological agent of disease in cattle. brv isolates have been detected in the stools of neonatal calves with diarrhea in both iowa and ohio and in several areas of europe. however, this virus has been reported only once in canada. therefore, a study was performed to determine the extent to which bovine torovirus is present in calves with diarrhea from farms in southern ontario. a total of 118 fecal samples from symptomatic ca ...	1998	9574689
risk factors for infection with verocytotoxigenic escherichia coli in cattle on ontario dairy farms.	risk factors for prevalent infection with verocytotoxigenic escherichia coli (vtec) were studied in a random sample of 886 cows and 592 calves under 3 months of age on 80 randomly selected dairy farms in southern ontario. fecal-culture supernatants from each animal were screened for verocytotoxicity using a vero cell assay (vca) and for verocytotoxin (vt) genes by a polymerase chain reaction (pcr) procedure. up to 20 f. colt isolates from positive samples were tested for vt production using vca ...	1998	9604270
associations between milk-protein production and reproduction, health, and culling.	associations between protein production and individual-cow reproductive performance, health, and culling were investigated in a 2-year observational study involving a convenience sample of 75 ontario, 5 alberta, and 3 nova scotia dairy farms. protein production was defined by 305-day lactation protein yields and by estimated breeding values for protein yield. after controlling for the level of milk production, herd, parity, breed, and season of calving, there were no significant associations bet ...	1998	9638779
ontario bulk milk somatic cell count reduction program: progress and outlook.	the objective of this study was to describe the results of the ongoing somatic cell count (scc) reduction program in ontario, canada and to provide an outlook regarding the possible scenarios beyond the final stages of the current reduction program. the data were from all of the approximately 9500 farms in the province of ontario during the last 10 yr and included monthly data for kilograms of milk sold, mean milk component measurements, and milk quality measurements (bulk milk scc, plate loop c ...	1998	9684160
investigating potential risk factors for seasonal variation: an example using graphical and spectral analysis methods based on the production of milk components in dairy cattle.	the objective of this study was to illustrate methods for investigating factors associated with seasonality, using milk-component production as an example. milk-protein and fat percentages showed a seasonal pattern; percentages were lowest during june and july and highest in october and november. graphical methods were used to compare herd calving patterns to seasonal production patterns and spectral analysis were used to compare seasonal production patterns between farm groups with different ma ...	1998	9785373
herd-level test performance based on uncertain estimates of individual test performance, individual true prevalence and herd true prevalence.	a generalized model was derived for understanding the performance of herd-testing protocols when there is uncertainty and variability in individual-level sensitivity, specificity, prevalence of infection within infected herds, and prevalence of infected herds in the population. the model uses monte-carlo techniques to provide estimates of test performance for a dichotomous classification of herd-disease status. uncertainty and variability in input assumptions are described using empirical and pa ...	1998	9785375
the association of titers to haemophilus somnus, and other putative pathogens, with the occurrence of bovine respiratory disease and weight gain in feedlot calves.	serum samples were obtained from 602 calves (from 19 groups in four feedlots: three in ontario, and one in alberta) upon arrival at the feedlot and 28 d later. of these calves, 202 developed bovine respiratory disease (brd) and 400 did not develop brd. based on high antibody titers noted upon arrival, we infer that most calves were exposed to haemophilus somnus prior to arrival at the feedlot. within a group, calves with high titers on arrival had a reduced risk of developing brd later. most cal ...	1998	9798091
temporal and geographical distributions of reported cases of escherichia coli o157:h7 infection in ontario.	the distribution of 3001 cases of verocytotoxigenic escherichia coli (vtec) reported in the province of ontario, canada, were examined to describe the magnitude of this condition geographically and to evaluate the spatial relationship between livestock density and human vtec incidence using a geographical information system. incidence of vtec cases had a marked seasonal pattern with peaks in july. areas with a relatively high incidence of vtec cases were situated predominantly in areas of mixed ...	1999	10355782
associations of the bovine major histocompatibility complex drb3 (bola-drb3) with production traits in canadian dairy cattle.	associations of two alleles of the bovine major histocompatibility complex drb3 gene (bola-drb3) with lowered somatic cell score (scs) and occurrence of disease (bola-drb3.2* 16 and *23, respectively) have previously been documented. the objective of this study was to evaluate potential relationships between bola-drb3 alleles with production traits, namely 305-day milk, milk fat and milk protein yield, in a population of canadian dairy cattle (holstein, n = 835 and jersey, n = 66) over the cours ...	1999	10376308
the potential of open learning in animal breeding.	animal breeding education is presently facing many challenges. these include rapid changes in breeding knowledge and technology, resource and funding restrictions, and altering demographics of the learner and the animal breeding industry. these challenges can be met via an open learning educational format. this nontraditional approach is based on the needs of individual learners, not the interests of the teacher or the institution. an important feature of open learning is its appropriateness for ...	1999	10416175
a review of anthrax in canada and implications for research on the disease in northern bison.	during the first half of the century, the majority of anthrax outbreaks in canada occurred in the southern portions of ontario and quebec and were often associated with pastures contaminated by effluent from textile industries dealing with imported animal materials. in 1952, introduction of federal regulations requiring disinfection of these materials greatly reduced the incidence of anthrax in eastern canada. since 1962, domestic outbreaks of the disease have been reported almost exclusively in ...	1999	10475950
lung volume reduction for emphysema and the canadian lung volume reduction surgery (clvr) project.	to review the literature on the surgical treatment of emphysema and to present preliminary results from a pilot study of lung volume reduction (lvr) surgery.	1999	10202218
molecular typing methods to investigate transmission of escherichia coli o157:h7 from cattle to humans.	the utility of phage typing, pulsed-field gel electrophoresis (pfge), and plasmid profile analysis was compared, to differentiate between canadian escherichia coli o157:h7 strains of human (n = 27) and cattle (n = 24) origin. the diversity indices for phage typing, plasmid analysis and pfge were 0.85, 0.69 and 0.93, respectively. pfge and phage typing were also applied to study the role of direct transmission of e. coli o157:h7 from cattle to humans on isolates collected from two separate farm o ...	1999	10487637
morphologic lesions in type 2 bvdv infections experimentally induced by strain bvdv2-1373 recovered from a field case.	widespread outbreaks of severe acute bvdv, some associated with hemorrhagic syndrome (hs), were reported in quebec and ontario in 1993. these outbreaks caused significant economic hardship in infected herds. in the ontario outbreak 150 dairy, 600 beef and 100 milk and grain fed veal herds were affected with losses estimated at $40000-$10000 per herd in lost animals, milk production, abortions and genetics. fever, pneumonia, diarrhea, and sudden death occurred in all age groups of cattle. abortio ...	2000	11042409
evaluation of the reveal and safepath rapid escherichia coli o157 detection tests for use on bovine feces and carcasses.	the reveal (neogen corp., lansing, mich.) and safepath (safepath laboratories llc, st. paul, minn.) tests were evaluated for their performance as beef fecal and beef carcass escherichia coli o157:h7 monitoring tests. agreement between these tests and a reference test system was determined using naturally contaminated bovine feces and beef carcasses. the reference system utilized immunomagnetic separation with plating onto cefixime, tellurite, sorbitol macconkey agar, followed by colony testing u ...	2000	10914650
veterinary public health in the nepal himalaya.		2000	11126497
estimates of within-herd incidence rates of mycobacterium bovis in canadian cattle and cervids between 1985 and 1994.	we analysed the individual-animal data from six of the nine outbreaks of tuberculosis in canadian cattle and cervids from 1985 to 1994. a "positive/reactor" animal was one which had either a positive culture or a positive or suspicious reaction on a mid-cervical, comparative cervical, or gross or histopathological test for tuberculosis. individual-animal data were collected only for herds which had one or more positive/reactor animals. data were collected from the outbreak records in the regiona ...	2000	10821964
british beef, ontario water and dead crows.		2000	16808048
relationships between milk urea concentrations and nutritional management, production, and economic variables in ontario dairy herds.	the objectives of this study were to describe the relationships between milk urea concentrations and nutritional management, production, and economic variables in commercial dairy herds. dairy herd improvement (dhi) test-day milk urea data, production data, and information on ration nutrient composition and feeding management programs were collected over a 13-mo period from 53 commercial ontario dairy herds. economic variables included gross milk revenue, feed costs, and income over feed costs. ...	2001	11384039
milk urea testing as a tool to monitor reproductive performance in ontario dairy herds.	dairy herd improvement test-day data, including milk urea concentrations measured using infrared test method, were collected from 60 commercial ontario holstein dairy herds for a 13-mo period between december 1, 1995, and december 31, 1996. the objective of the study was to describe, at the cow and the group level, the relationship between dhi milk urea concentrations and reproductive performance in commercial dairy herds. when interpreted at the cow level, there was no association between milk ...	2001	11417698
emergence of salmonella typhimurium definitive type 104 (dt104) as an important cause of salmonellosis in horses in ontario.	salmonella typhimurium definitive type 104 (dt104) has emerged as a common cause of salmonellosis in humans and cattle, yet previous reports involving horses are sparse. this study reports the emergence of dt104 as an important pathogen in horses in ontario. the first clinical case of dt104 infection at the ontario veterinary college was identified in 1997. seventeen cases of dt104-associated salmonellosis were identified between 1997 and 2000. in 2000, 12 of 13 cases of salmonellosis were due t ...	2001	11665427
factors associated with milk urea concentrations in ontario dairy cows.	all dhi test-day data, including milk urea concentrations measured by infrared test method, were collected from 60 commercial ontario holstein dairy herds for a 13-mo period between december 1, 1995, and december 31, 1996. the objectives of this study were to describe the relationships between milk urea concentrations and seasonal factors, sampling factors, cow factors, and test-day production of milk, milk fat, protein, and scc. milk urea was associated with month and season; concentrations wer ...	2001	11210021
elimination of rabies from red foxes in eastern ontario.	the province of ontario (canada) reported more laboratory confirmed rabid animals than any other state or province in canada or the usa from 1958-91, with the exception of 1960-62. more than 95% of those cases occurred in the southern 10% of ontario (approximately 100,000 km2), the region with the highest human population density and greatest agricultural activity. rabies posed an expensive threat to human health and significant costs to the agricultural economy. the rabies variant originated in ...	2001	11272485
assessment of trace mineral and vitamin e status beef cows in ontario.		2001	11360863
bovine coronaviruses associated with enteric and respiratory diseases in canadian dairy cattle display different reactivities to anti-he monoclonal antibodies and distinct amino acid changes in their he, s and ns4.9 protein.	bovine coronavirus isolates associated with recent outbreaks of respiratory disease in ontario and quebec dairy farms were compared to reference strains known to be responsible for neonatal calf diarrhea (ncd) or winter dysentery (wd) of adult cattle. in respect to their hemagglutinating properties and their higher rde activities with rat erythrocytes, wdbcov strains differed from ncdbcov strains and respiratory bovine coronaviruses rbcov strains. serologically, three mabs directed to the he gly ...	2001	11376845
a longitudinal study of gastrointestinal parasites in canadian dairy farms. the value of an indirect ostertagia ostertagi elisa as a monitoring tool.	the general objective of this study was to evaluate a crude ostertagia ostertagi antigen enzyme-linked immunosorbent assay (elisa) for monitoring gastrointestinal parasites in lactating dairy cattle. a longitudinal study of gastrointestinal parasites in lactating dairy cows was carried out in 38 herds in four provinces of canada (prince edward island, quebec, ontario and saskatchewan) from september 1999 to october 2000. bulk tank milk, cow milk, serum and fecal samples were collected monthly or ...	2002	12127251
occurrence and characterization of resistance to extended-spectrum cephalosporins mediated by beta-lactamase cmy-2 in salmonella isolated from food-producing animals in canada.	resistance of salmonella to extended-spectrum cephalosporins (escs) is being reported with increasing frequency. in humans, infections with salmonella resistant to escs threaten the efficacy of ceftriaxone, the drug of choice for treating salmonellosis in children. to determine the occurrence of resistance to escs, we examined 8426 strains isolated from food-producing animals in canada in 1994-99 for reduced susceptibility or resistance to ceftriaxone. of the 8 such strains identified (7 from tu ...	2002	12146884
neospora caninum serostatus and milk production of holstein cattle.	to determine whether neospora caninum serostatus was associated with milk production among holstein cattle in ontario.	2002	12387387
neospora caninum serostatus and culling of holstein cattle.	to determine whether time until culling or risk of culling was associated with neospora caninum serostatus among holstein cattle in dairy herds in ontario.	2002	12387388
the use of negative binomial modelling in a longitudinal study of gastrointestinal parasite burdens in canadian dairy cows.	the epidemiology of bovine gastrointestinal nematodes was investigated through a 1-year (october 1999 to september 2000) longitudinal study in 38 canadian dairy herds from 4 different provinces (prince edward island, quebec, ontario, saskatchewan). for each herd, fecal egg counts from 8 randomly selected animals were performed on a monthly or quarterly basis. larval cultures were performed once, to determine the species breakdown of the parasites. all producers were interviewed regarding herd ma ...	2002	12418780
associations between indicators of livestock farming intensity and incidence of human shiga toxin-producing escherichia coli infection.	the impact of livestock farming on the incidence of human shiga toxin-producing escherichia coli (stec) infection was assessed by using several livestock density indicators (ldi) that were generated in a systematic approach. a total of 80 ldi were considered suitable proxy measures for livestock density. multivariate poisson regression identified several ldi as having a significant spatial association with the incidence of human stec infection. the strongest associations with human stec infectio ...	2002	11927021
adenoviral infection in captive moose (alces alces) in canada.	adenoviral infection was associated with hemorrhagic enteritis, serosal hemorrhages, and severe pulmonary edema in six captive moose (alces alces) in toronto, ontario, canada: an adult female moose and three calves in 1985 and two calves in 1998. adenoviral disease was suspected based on histological findings of systemic vasculitis and widespread thrombosis associated with amphophilic intranuclear inclusions in endothelial cells. diagnosis was confirmed by immunohistochemistry using antiserum to ...	2002	12216797
characterization of waterborne outbreak-associated campylobacter jejuni, walkerton, ontario.		2003	14609457
clostridium botulinum type d intoxication in a dairy herd in ontario.	thirty-four holstein cows died after exposure to clostridium botulinum type d toxin, presumably from contaminated haylage. the presence of type d toxin in ruminal contents was confirmed by mouse inoculation. this is the first confirmation by direct toxin isolation of c. botulinum type d toxin in cattle in north america.	2003	12839245
comparison of prices paid for feeder calves sold at conventional auctions versus special auctions of vaccinated or conditioned calves in ontario.	to determine whether vaccinated or conditioned feeder calves sold through special auctions in ontario commanded a premium, compared with feeder calves sold at conventional auctions, and whether various physical characteristics of the calves were associated with the sale price.	2003	12959387
health performance of feeder calves sold at conventional auctions versus special auctions of vaccinated or conditioned calves in ontario.	to compare health performance during the first 28 days in the feedlot for vaccinated or conditioned feeder calves sold through special auctions in ontario with health performance for calves sold through conventional auctions in the province.	2003	12959388
antimicrobial susceptibility of hazard analysis critical control point escherichia coli isolates from federally inspected beef processing plants in alberta, saskatchewan, and ontario.	a survey to estimate the prevalence of antimicrobial resistance in escherichia coli was conducted in 7 canadian federally inspected processing plants during 2001. escherichia coli isolates were recovered during routine hazard analysis critical control point sampling from beef carcasses and trim and subsequently tested for their antimicrobial susceptibility by using susceptibility panels. of the 2653 isolates analyzed, 68% were sensitive to all 18 antimicrobials tested. for 14 of the 18 antimicro ...	2003	14524625
a socio-ecological autopsy of the e. coli o157:h7 outbreak in walkerton, ontario, canada.	the socio-political context of modern environmental health disasters tends to be defined as being outside the scope of official public health and epidemiological investigations into the causes of such disasters. on the other hand, popular accounts of these disasters tend to focus exclusively on the role of particular individuals and/or political actors, while minimizing the role of ecological factors. it is argued that an exclusive focus on either set of causal factors gives an incomplete or dis ...	2004	15081208
estimating potential environmental loadings of cryptosporidium spp. and campylobacter spp. from livestock in the grand river watershed, ontario, canada.	exposure to waterborne pathogens in recreational or drinking water is a serious public health concern. thus, it is important to determine the sources of pathogens in a watershed and to quantify their environmental loadings. the natural variability of potentially pathogenic microorganisms in the environment from anthropogenic, natural, and livestock sources is large and has been difficult to quantify. a first step in characterizing the risk of nonpoint source contamination from pathogens of lives ...	2004	15260337
enhanced surveillance for salmonella newport.		2004	15262878
udder health in dairy cattle infected with neospora caninum.	blood samples were collected from 3449 cows on 57 representative ontario dairy herds during the summer of 1998 and analysed for antibody to neospora caninum using an elisa. forty-eight herds (2742 cattle) contained at least one n. caninum-seropositive animal. two composite milk samples were collected from all cattle: the first on the day of blood collection and the second 68 to 365 days later. all milk samples were submitted for bacteriological culture. ontario dairy herd improvement corporation ...	2004	15325765
determinants of the geographical distribution of endemic giardiasis in ontario, canada: a spatial modelling approach.	giardiasis surveillance data as well as drinking water, socioeconomic and land-use data were used in spatial regression models to investigate determinants of the geographic distribution of endemic giardiasis in southern ontario. higher giardiasis rates were observed in areas using surface water [rate ratio (rr) 2.36, 95 % ci 1.38-4.05] and in rural areas (rr 1.79, 95 % ci 1.32-2.37). lower rates were observed in areas using filtered water (rr 0.55, 95 % ci 0.42-0.94) and in those with high media ...	2004	15473161
genetic susceptibility to neospora caninum infection in holstein cattle in ontario.	neospora caninum has been reported to be an important cause of endemic fetal loss and occasional abortion epidemics in cattle around the world. this study examined 12,016 sera collected from 9723 holstein cows on 125 herds across ontario in 1998, 1999, and 2000. an enzyme-linked immunosorbent assay was used to examine the sera for antibodies to n. caninum. the overall prevalence of n. caninum antibodies in the cattle was 11.2% and the prevalence in individual herds varied from 0 to 70.4%. among ...	2004	15483182
antibiotic resistance of salmonella isolated from hog, beef, and chicken carcass samples from provincially inspected abattoirs in ontario.	the emergence of antimicrobial-resistant salmonella organisms, especially salmonella typhimurium dt104, has been reported in many countries, including the united states and canada. the purposes of this study were to determine the antimicrobial resistance patterns of salmonella isolated from hog, beef, and chicken carcasses from provincially inspected abattoirs in ontario and to determine the agreement between the agar dilution method and the microbroth dilution method for measurement of antimicr ...	2004	15035356
the association of herd milk production and management with a return-over-feed index in ontario dairy herds.	associations of herd milk production and management variables to a return-over-feed (rof) herd profit index were examined among 95 dairy farms. the rof index is derived from 2 important determinants of profit on dairy farms: milk income and feed cost. all producers were participants in the dairy herd improvement (dhi) rof program in ontario, canada during 2002. nutrition, housing, health, and other management data were collected through a phone survey of herd managers. herd milk production, milk ...	2005	15591408
estimates of genetic parameters for canadian holstein female reproduction traits.	age at first insemination, days from calving to first insemination, number of services, first-service nonreturn rate to 56 d, days from first service to conception, calving ease, stillbirth, gestation length, and calf size of canadian holstein cows were jointly analyzed in a linear multiple-trait model. traits covered a wide spectrum of aspects related to reproductive performance of dairy cows. other frequently used fertility characteristics, like days open or calving intervals, could easily be ...	2005	15905449
prevalence of cryptosporidium parvum infection in southwestern ontario and its association with diarrhea in neonatal dairy calves.	cryptosporidium parvum infection was detected in 203 (40.6%) of 500 ontario dairy calves aged 7 to 21 d, on a convenience sample of 51 farms with a history of calf diarrhea. within-farm prevalence ranged from 0% to 70%, and both shedding and intensity of shedding were significantly associated with diarrhea. this parasite appears to be common in ontario dairy calves and important as a cause of dairy calf scours in the province.	2005	15943123
tie-stall design and its relationship to lameness, injury, and cleanliness on 317 ontario dairy farms.	the objective of this study was to identify relationships between tie-stall design and selected cow-based injury, lameness, and cleanliness measurements. all lactating dairy cows (n = 17,893) from 317 ontario tie-stall dairy farms were evaluated once between march and september 2003. stall dimensions were recorded and cows were scored for neck and hock lesions, broken tails, back arch, hind claw rotation, and udder and hind limb cleanliness. neck lesions were significantly associated with tie-ra ...	2005	16107410
the prevalence of milk and serum antibodies to mycobacterium avium subspecies paratuberculosis in dairy herds in ontario.	this study randomly surveyed 50 dairy herds in ontario; 18% and 30% of herds had 2 or more milk or serum enzyme-linked immunosorbent assay (elisa)-positive cows, respectively. the apparent cow level prevalence was 1.7% and 2.6% on the milk and serum elisa, respectively. the serum and milk assays agreed moderately.	2005	16422065
stall dimensions and the prevalence of lameness, injury, and cleanliness on 317 tie-stall dairy farms in ontario.	the study objectives were to provide a province-wide description of stall dimensions and the aspects of cattle welfare linked to stall design in the tie-stall industry. data on stall design; stall dimensions; and the prevalence of lameness, injury, and hind limb and udder cleanliness in lactating dairy cattle were collected from a sample of 317 tie-stall farms across ontario. the majority of the study farms (90%) had stalls with dimensions (length, width, tie-chain length, and tie rail height) t ...	2005	16454382
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 ...	2005	15759828
risk factors associated with neospora caninum abortion in ontario holstein dairy herds.	the objective of this epidemiological study was to identify risk factors for neospora caninum-related abortions in ontario holstein dairy herds. a total of 88 herds, consisting of 5080 cattle, and utilizing dairy herd improvement (dhi) services, were divided into three groups. case (n = 30) and first control (n = 31) herds were selected from 1998 and 1999 fetal abortion submissions to the animal health laboratory, university of guelph, that were histopathologically positive or negative, respecti ...	2005	15710518
bovine viral diarrhea virus in alpaca: abortion and persistent infection.	an alpaca herd in eastern ontario experienced vague signs of illness, including anorexia and lethargy in 9 animals, 2.5 months after the addition of a chronically ill cria and his dam to the farm. subsequently 2 alpaca had early pregnancy loss; one aborted at 5.5 months gestation and the other at 7 months gestation. seventeen were found to have serum antibody to bovine viral diarrhea virus (bvdv), with highest titers to bvdv type 1. the fetus that was aborted at 5.5 months gestation, 3 months af ...	2005	16475521
iron deficiency and anemia prevalence and associated etiologic risk factors in first nations and inuit communities in northern ontario and nunavut.	anemia is common among children in aboriginal communities in canada. the objectives of this study were to determine the prevalence of anemia and to identify its associated risk factors among young children in aboriginal communities in northern ontario and nunavut.	2005	16625803
efficacy of monensin sodium for the reduction of fecal shedding of mycobacterium avium subsp. paratuberculosis in infected dairy cattle.	reducing the quantity of mycobacterium avium subsp. paratuberculosis (map) being shed by cows with johne's disease should decrease the risk of spread of this disease to young stock. previous work has suggested that monensin sodium decreases the pathologic lesions associated with johne's disease, but the impact on shedding of viable map remains unknown. after serologic screening of 32 dairy herds in southwestern ontario, 228 cows from 13 of these herds were enrolled into a randomized clinical tri ...	2006	16631972
monensin might protect ontario, canada dairy cows from paratuberculosis milk-elisa positivity.	our objective was to define the role of monensin sodium in protecting cows from being milk-elisa positive for paratuberculosis in ontario, canada dairy herds. in total, 4933 dairy cows from 94 herds were enrolled in this cross-sectional study. forty-four of the enrolled herds were selected purposively by their herd veterinarian and another 50 herds were randomly selected from a local milk production-recording agency. a herd-management survey was completed on each farm during the months of may th ...	2006	16787675
genotype and subtype analyses of cryptosporidium isolates from dairy calves and humans in ontario.	to assess the importance of dairy cattle as a source of human cryptosporidium infections in ontario, canada, 44 cryptosporidium isolates from neonatal dairy calves and 11 from sporadic human cases of cryptosporidiosis in the province were genotyped by pcr-rflp analyses of the cryptosporidium oocyst wall protein (cowp) and 18s rrna genes. isolates were also subtyped by sequence analysis of the 60-kda glycoprotein (gp60) gene. all bovine isolates successfully subtyped belonged to cryptosporidium p ...	2006	16565813
diseases and pathogens associated with mortality in ontario beef feedlots.	this study determined the prevalence of diseases and pathogens associated with mortality or severe morbidity in 72 ontario beef feedlots in calves that died or were euthanized within 60 days after arrival. routine pathologic and microbiologic investigations, as well as immunohistochemical staining for detection of bovine viral diarrhea virus (bvdv) antigen, were performed on 99 calves that died or were euthanized within 60 days after arrival. major disease conditions identified included fibrinos ...	2006	16566254
evaluation of a contract breeding management program in selected ohio dairy herds with event-time analysis i. cox proportional hazards models.	an observational study was conducted in order to assess the impact of a contract breeding program on the reproductive performance in a selected group of ohio dairies using event-time analysis. the contract breeding program was offered by a breeding co-operative and featured tail chalking and daily evaluation of cows for insemination by co-operative technicians. dairy employees no longer handled estrus detection activities. between early 2002 and mid-2004, test-day records related to production a ...	2006	16887223
control of coagulation: a gift of canadian agriculture.	vitamin k, heparin and their antagonists remain the basis of coagulation therapies today, more than half a century after their discovery. failure of blood clotting in chicks that were fed a fat-depleted diet was observed by william mcfarlane, william graham jr. and frederick richardson of the ontario agricultural college; it led to the search that yielded vitamin k. investigation of hemorrhagic disease in cattle by francis schofield of the ontario veterinary college found an anti-thrombin substa ...	2006	17330453
the relationship between herd level disease incidence and a return over feed index in ontario dairy herds.	the objective of the current research was to examine the association of herd level disease incidence with the return over feed (rof) (milk income minus feed cost) herd profit index offered through canwest dairy herd improvement. the lactational incidence risks (lir) for displaced abomasum, retained placenta, clinical mastitis, milk fever, clinical ketosis, and lameness submitted by producers (n = 48) were similar to previous reports. however, there was no negative association of clinical disease ...	2006	16933554
antibiotic resistance of campylobacter jejuni and campylobacter coli isolated from hog, beef, and chicken carcass samples from provincially inspected abattoirs in ontario.	campylobacterjejuni is one of the most common causes of bacterial foodborne infection in the united states, and there are reports of resistance of campylobacter spp. to antimicrobial agents used for the treatment of gastroenteritis. the purpose of this study was to determine the antimicrobial resistance patterns of campylobacter spp. isolated from hog, beef, and chicken carcasses from provincially inspected abattoirs in ontario. the agar dilution method was performed to measure antimicrobial res ...	2006	16416896
prevalence and molecular characterization of giardia duodenalis and cryptosporidium spp. in dairy cattle in ontario, canada.	giardia duodenalis and cryptosporidium spp. are intestinal protozoan parasites that infect a wide range of host species, including humans. molecular characterization of these parasites has demonstrated that a number of genotypes and species are common to both humans and animals, and that zoonotic transmission may occur. numerous studies have reported a high prevalence of g. duodenalis and cryptosporidium spp. in cattle, particularly calves, and these animals are frequently associated with zoonot ...	2007	17964724
update on parathyroid hormone: new tests and new challenges for external quality assessment.	it is now 43 years since berson and yalow published the first radio-immunoassay (ria) for parathyroid hormone (pth) [s.a. berson, r.s. yalow, g.d. aurbach, j.t. potts, immunoassay of bovine and human parathyroid hormone. proc natl acad sci u s a 49 (1963) 613-617] [1]. since then, there have been marked advances in our understanding of this peptide hormone, its mechanism of action and biological regulation [j.t. potts, parathyroid hormone: past and present. j. endocrinol. 187 (2005) 311-325] [2] ...	2007	17493603
tsetse and other biting fly responses to nzi traps baited with octenol, phenols and acetone.	octenol (1-octen-3-ol), acetone, 4-methylphenol, 3-n-propylphenol, and other potential attractants (human urine, stable fly faeces), as well as guiacol, creosol (potential repellents), were tested as baits for biting flies in north america using standard phthalogen blue if3gm cotton nzi traps, or similar commercial polyester traps. baits were tested during the summers of 2001-04 at a residence in canada and during january-august 2001 at a dairy in the u.s.a. behaviour in the presence of octenol ...	2007	17373949
tracking host sources of cryptosporidium spp. in raw water for improved health risk assessment.	recent molecular evidence suggests that different species and/or genotypes of cryptosporidium display strong host specificity, altering our perceptions regarding the zoonotic potential of this parasite. molecular forensic profiling of the small-subunit rrna gene from oocysts enumerated on microscope slides by u.s. environmental protection agency method 1623 was used to identify the range and prevalence of cryptosporidium species and genotypes in the south nation watershed in ontario, canada. fou ...	2007	17483276