Pattern of diarrhoea in newborn beef calves in south-west France

A prospective study was carried out on 94 randomly selected beef herds in the Midi-Pyrénées region in France. The objective was to describe diarrhoea and mortality in beef calves from birth to 30 days of age. Calves (3,080) were followed from December 1995 to April 1996, and a total of 700 visits allowed records of herd management practices, individual data and environmental conditions to be collected. The incidence rate for diarrhoea during the neonatal period was 14.6%, and varied markedly between herds. Eighteen herds did not suffer from diarrhoea, while five herds had an incidence of more than 50%. Results indicate that 52% of diarrhoea appears during the first week and only 15% after the second week of life. The greatest risk of diarrhoea for a calf was during the first and second weeks of life (7.9 and 6.5 times, respectively). The month of birth was also significantly associated with morbidity, the highest incidence was observed in December and March (17.6 and 23.6%, respectively). Escherichia coli was isolated from 20.3% of faecal samples and appeared earlier during the first days of life. Rotavirus was frequently isolated (47.4%) from samples. Coronavirus was positive for only 16.5% but was significantly associated with diarrhoea. Cryptosporidium was less frequent (15.6%). The global mortality rate was 3.6% and was two-times higher in December than in other months. Forty per cent of herds did not exhibit mortality, and 10% had mortality rates greater than 10%. This study confirms previously reported data, and with greater precision and details on diarrhoea and mortality incidences among herds, age and month of birth in suckling beef calves.     

Dam-related effects on heart girth at birth,morbidity and growth rate from birth to 90 days of age in Swedish dairy calves

We investigated the effects of dam-related factors (such as calving performance, milk leakage, diseases, milk production, and somatic-cell count (SCC)) on heart girth at birth and the incidence risk of diarrhoea and respiratory disease during the first 90 days in Swedish dairy calves. The effects of these dam-related factors and environmental and management-related (but not dietary) factors on the calves' growth rate during the first 90 days of life also were analysed. The study used nearly 3,000 heifer calves born in 1998 on 122 farms in the south-west of Sweden. Individual health records were kept by the farmers and visiting project veterinarians. The calf's heart girth was measured at birth and weaning. We used generalised linear mixed models for the size of the calf at birth and growth rate. Variables associated with the heart girth at birth were breed, calving performance, mastitis in the dam in the last 49 days before calving, milk production and parity. Variables associated with the growth rate were breed, calving performance, disease in the calf during its first 90 days of life, heart girth at birth, and housing of calves. The effect of the dam on the relative risk of diarrhoea and/or respiratory disease in the calf was evaluated by a generalised linear mixed model with a logit link. Morbidity in the dam during late pregnancy, retained placenta and SCC were associated with the relative risk of respiratory disease in the calf. None of the explanatory variables (other then breed) was associated with the relative risk of diarrhoea.     

A case-control study of Washington dairy herds experiencing drug residue violations in market calves

The purpose of this case-control study was to examine the association between management practices and the occurrence of violative drug residues in calves originating from Washington dairies. In 1992, 74 dairies were identified as first-time offenders sending to abattoirs calves less than 1 week of age that had violative residue levels. Of these, 56 answered a subset of previously validated management questions from the 1991–1992 US National Animal Health Monitoring System National Dairy Heifer Evaluation Program (NDHEP) study during a violation investigation and comprised the case group. The controls were the 51 randomly selected Washington dairies that participated in the NDHEP, completed the four NDHEP questionnaires, and had not been identified as having residue violations. Management factors investigated were those associated with maternity and pre-weaning hygiene, vaccination and preventive practices, type and management of liquid calf feed, and general management. Other factors included herd somatic cell count (SCC), the presence of clinical signs associated with diseases of body systems, and herd size. Significant associations were detected between violation occurrence and the management of calving cows, colostrum volume and management, and the person responsible for calf care. Significant associations but of the wrong direction were found between violation occurrence and type and management of liquid calf feed. No significant associations were detected between violation occurrence and the remaining management factors, herd size, animals entering the herd, or SCC.     

Risk factors for calf mortality in large Swedish dairy herds

The aim of this study was to identify possible risk factors for 1-90 day calf mortality in large Swedish dairy herds. Sixty herds with a herd size of ≥160 cows were visited once between December 2005 and March 2006. Thirty herds were known to have low mortality (LM) and 30 were known high mortality herds (HM). Upon the visit, data about housing and management was collected from interviews with personnel responsible for the calves. The herd status regarding the calves' passive transfer (total protein), levels of α-tocopherol, β-carotene and retinol, and excretion of faecal pathogens (Cryptosporidium spp., Escherichia coli F5, rota and corona virus) was evaluated based on targeted sampling of high risk calf groups; in each herd, blood and faecal samples were collected from calves 1-7 and 1-14 days old, respectively. Similarly, the herd status regarding clinical respiratory disease in calves and history of respiratory virus exposure was evaluated based on lung auscultations and blood samplings of calves 60-90 days old. The median calf mortality risk (in calves 1-90 days of age) among HM herds was 9% (Range: 6-24%) and among LM herds 1% (Range: 0-2%). LM and HM herds were compared using five logistic regression models, covering potential risk factors within different areas: "Disease susceptibility", "Factors affecting the gastrointestinal tract", "Factors related to transmission of infectious disease", "Hygiene" and "Labour management". The percentage of calves, 1-7 days old, with inadequate serum concentrations of α-tocopherol and β-carotene were significantly higher in HM herds compared to LM herds and also associated with higher odds of being a HM herd (OR=1.02; p=0.023 and OR=1.05; p=0.0028, respectively). The variable "Average number of faecal pathogens in the sampled target group" was significantly associated with higher odds of being a HM herd (OR=4.65; p=0.015), with a higher average in HM herds. The percentage of calves with diarrhoea treated with antibiotics was significantly higher in HM herds and was associated with higher odds of being a HM herd (OR=1.08; p=0.021). The median age at death of calves in the age interval 1-90 days that died during a one-year period was significantly lower among HM herds (13 days) than in LM herds (24 days) (p=0.0013) The results indicate that gastrointestinal disorders may be an important cause of calf mortality in large Swedish dairy herds. Furthermore, our study provides additional indications that fat soluble vitamins might play an important role for calf health.     

Factors affecting calf mortality in Iranian Holstein dairy herds

The objective of this study was to document mortality reasons and risk factors for mortality in dairy calves in the northeast of Iran. This was a prospective cohort study of calves born on ten commercial dairy herds from 21 March 2009 to 20 March 2010. A total of 4097 live calves were followed for 90 days after birth. For each calf details of sex, parity of the dam, type of parturition and season of birth were recorded. The interval (in days) from the date of birth to the date of death and the reason for death was recorded for those calves that died before 90 days of age. A Cox proportional hazards model, including a frailty term to account for unmeasured herd-level effects was developed to quantify the effect of factors associated with time to death. Two hundred and sixty-six (6.5%, 95% CI: 5.8-7.3%) of the 4097 live-born calves died or were euthanised before 90 days of age. The most important reasons for death were digestive tract disorders (58% of all deaths, 95% CI: 52-64%) followed by respiratory diseases (13% of all deaths, 95% CI: 9-17%). Calves exposed to dystocia at birth had 2.09 (95% CI: 1.49-2.92) times the daily hazard of death compared with calves born from a normal calving. The daily hazard of death for calves born in the summer was 1.93 (95% CI: 1.41-2.64) times greater than the hazard for those calves born in the autumn. Inclusion of the herd-level frailty term had a significant effect on hazard estimates indicating that the study herds were heterogeneous in the distribution of unmeasured herd-level factors influencing calf survival. Our results show that diarrhoea is the most important cause of calf mortality in dairy herds in this area of Iran and that environmental and management factors affect calf mortality rate.     

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 much more common in heifers than in cows. Separate statistical models of dystocia and stillbirth for cows and heifers were created. Dystocia in cows was associated with calf sex, previous calving assistance and large breed type and birth weight. Variations in 1987 cow herd dystocia rates were associated with calving season, location and density, and the herd dystocia rate in 1986. Dystocia in heifers was associated with large breed type and calf birth weight. Herd-level management practices associated with increased heifer dystocia rates included breeding heifers to calve earlier than cows and rearing heifers together with the cow herd. Stillbirths for both cows and heifers were associated with calving assistance, particularly hard assistance. Herd-level management and other factors were unassociated with stillbirths.     

Herd management practices associated with paratuberculosis seroprevalence in Dutch dairy herds

We describe the paratuberculosis management practices applied in dairy herds in the Netherlands. The findings from paratuberculosis seronegative and seropositive herds were compared to discover possible risk factors. In total, 370 randomly selected herds with > or =20 dairy cows were surveyed. A questionnaire was used to collect data on current and previous paratuberculosis management practices. All cattle aged > or =3 years were serologically tested for paratuberculosis using an enzyme-linked immunosorbent assay. Herds with >33 tested cattle, of which only one was seropositive, were excluded to reduce the risk of including false-positive herds in the analysis. A comparison of the management data of the seronegative herds (n = 166) and the seropositive herds (n = 143) showed that in both groups important management measures for the prevention of paratuberculosis, such as calving in a cleaned calving area, removing the calf immediately after birth, and feeding paratuberculosis non-suspect roughage to calves, were used only rarely. However, such measures should be regarded as the critical first step to control the disease and/or reduce its prevalence. Using univariable analysis, four factors were statistically different between seronegative and seropositive herds: herd size, cows with clinical signs of paratuberculosis, prompt selling of clinically diseased cattle and feeding milk replacer. Using a multivariable logistic regression model, only herd size was a significantly different factor. These results indicate that most of the paratuberculosis preventive management measures were executed on these Dutch dairy farms only to a limited extent.     

Genetic and non-genetic factors associated with health and vitality traits in beef calves

Awareness and interest in calf health and wellbeing is intensifying, prompting change in the management and breeding decisions of producers and associated policy-makers. The objectives of the present study were to 1) quantify the risk factors associated with subjectively measured scores of vigor and birth size as well as diagnoses of scour and pneumonia in a large national dataset of beef calves, and 2) to estimate the contribution of genetic variance to such phenotypic measures. After edits, the data consisted of health and birth size data subjectively scored by producers on 88,207 calves born in 6,126 Irish beef herds. Vigor was recorded on a scale of 1 (very poor) to 5 (very good). Birth size was also scored on a scale of 1 (very small) to 5 (very large). Scour and pneumonia were both scored independently based on the suspected number of occurrence of each (0 = no occurrence, 1 = one occurrence, or 2 = more than one occurrence). On average, 14.7% of calves were recorded as having had at least one occurrence of scour within the first 5 mo of life, whereas 6.4% of calves were recorded as having had at least one occurrence of pneumonia within the first 5 mo of life. Relative to female calves, male calves had a worse vigor score and a suspected greater incidence of both scour and pneumonia. Relative to singletons, twins were, on average, smaller at birth, they had a worse vigor score, and they were more prone to scour. Calves born in the later periods of the calving season (i.e., late and very late) had a greater incidence of scour relative to calves in the herd born earlier in the calving season. Heritability estimates for vigor, birth size, and pneumonia were 0.12 (0.02), 0.33 (0.03), and 0.08 (0.02), respectively; no genetic variance was detected for scour. Breeding for vigorous calves that are less susceptible to pneumonia could provide producers with an additional strategy to ensure consumer concerns regarding food quality, safety, and calf wellbeing are being met.     

Losses over a 2-year period associated with fetal infection with the bovine viral diarrhea virus in a beef cow-calf herd in Saskatchewan.

In 1992, significant calf losses occurred between birth and weaning in a 650-cow Saskatchewan beef herd. These losses occurred subsequent to ill-thrift and disease, and every calf necropsied was found to be persistently infected with bovine viral diarrhea virus (BVDV). The objectives of this study were to describe the losses associated with fetal infection with BVDV in this herd and to determine why they occurred. For investigative purposes, blood samples were collected from the entire cow herd and the surviving calves at pregnancy testing in 1992, and tested by virus isolation for BVDV. Between 51 and 71 persistently infected calves were born in 1992. Bovine viral diarrhea virus was only isolated from calves. The only confirmed fetal infections with BVDV were recorded as the birth of persistently infected calves. However, abortions, reduced pregnancy rates, and delayed calvings were also recorded in the cow herd and may have been the result of fetal infections. The herd was monitored again in 1993. Fetal infections with BVDV were recorded as the birth of stunted, deformed, and persistently infected calves. The greatest losses due to fetal infection with BVDV in the 2 years of this study occurred in cows that were 3-years-old at calving (second calves). Bovine viral diarrhea virus appears to have remained endemic in this herd by transmission from persistently infected calves on young 3- and 4-year-old cows to naive calved 2-year-old cows that were mingled with them annually for rebreeding. Significant numbers of the 2-year-old cows remained naive to BVDV, because they were segregated from persistently infected calves at weaning, preventing cross-infection with BVDV.     

A questionnaire on the health, management, and performance of cow-calf herds in Québec.

Questionnaires were mailed to 520 cow-calf producers in Québec in order to compare management practices and herd performance according to herd size (small: < 40 females, or large: > or = 40 females) and in 4 geographic areas for the 1995 calving season. Owners of large herds adopted management practice and preventive measures more often than did owners of small herds. Average calving and weaning rates were 95% and 87% respectively. Average perinatal and preweaning mortality rates were between 4.9% and 5.6%. A greater percentage of owners with large herds than owners of small herds reported diarrhea and pneumonia problems. Among large herds, the number of herds experiencing pneumonia and calf mortality associated with diarrhea tended to be higher in areas of the northwest. Calf mortality due to pneumonia was higher in the northeast. No regional variation was found among small herds. Further research is needed to identify diseases risk factors.     

Herd-level risk factors for infectious diseases in Swedish dairy calves aged 0-90 days

The effect of environmental factors and management routines on the risk of diarrhoea, respiratory disease and other infectious diseases was investigated in 3081 heifer calves 0–90 days old in 122 Swedish dairy herds. The farmers kept records on cases of diseases in their heifer calves and in addition, project veterinarians clinically examined all calves every 2–3 months. At each visit, the veterinarians also measured the ammonia concentration and relative air humidity in the housing facilities for the calves. The cleanliness of the animals and their environment was recorded as a measure of the hygienic status of the farm. The presence or absence of draught (i.e. wind velocity > 0.5 m/s) was recorded twice during the study period. The effect of these factors, as well as the placing of the calf pens, the nature of the pen walls, air volume per animal, management factors (such as the status of the caretaker and feeding routines) and presence or absence of a bovine viral diarrhoea virus (BVDV) infection in the herd, was evaluated by means of a two-level variance component logistic model. The placing of calf pens along an outer wall was significantly associated with the risk of diarrhoea (odds ratio (OR): 1.92, P < 0.01). The risk for respiratory disease was significantly associated with an ammonia concentration below 6 ppm (OR: 0.42, P < 0.05) while the odds ratio for moderately to severely increased respiratory sounds was significantly associated with a BVDV infection in the herd (OR: 2.39, P < 0.05) and draught (OR: 3.7, P < 0.02). Absence of draught was significantly associated with the risk for infectious diseases other than diarrhoea and respiratory disease (OR: 0.42, P < 0.01).     

Body measurements of crossbred calves sired by Simmental bulls divergently selected for progeny first-calf calving ease in relation to birth weight

Simmental bulls (n = 27) were divergently selected on linear model first-calf calving ease expected progeny difference (CEPD) relative to birth weight expected progeny difference (BEPD) so that body measures of calves from sires whose progeny tended to be born either with more or less dystocia than expected from BEPD could be obtained. At birth, calf weight, head circumference, shoulder width, hip width, heart girth, cannon bone circumference and length, and body length were recorded for 204 calves. These measures had also been obtained from the Polled Hereford X Angus dams of the calves at their births. Sire differences (P less than .05) existed for calf cannon bone circumference and length before and after adjustment for gestation length and birth weight of the calf. Sire BEPD was positively associated with cannon and head circumferences independent of phenotypic birth weight and gestation length. No relationship existed between CEPD or threshold model first-calf calving ease expected progeny difference and any calf measure, either before or after adjustment for birth weight. Multivariate factor analysis was used to describe independent components of skeletal width, frame, and thickness after removal of birth weight effects; factors were not related to genetic merit for calving ease or observed calving performance. Independent of weight, newborn calf measures were not highly related to body measures at weaning or to dam birth measures. Body shape differences at constant weight existed in crossbred calves, but they were not related to sire genetic merit for calving ease or measured dystocia. Selection for calf body shape, independent of birth weight, would not reduce dystocia.     

Quantification,risk factors,and health impact of natural congenital infection with bovine viral diarrhea virus in dairy calves

OBJECTIVES: To estimate risk and identify risk factors for congenital infection with bovine viral diarrhea virus (BVDV) not resulting in persistent infection and examine effect of congenital infection on health of dairy calves. ANIMALS: 466 calves. PROCEDURES: Calves from 2 intensively managed drylot dairies with different vaccination programs and endemic BVDV infection were sampled before ingesting colostrum and tested with their dams for BVDV and BVDV serum-neutralizing antibodies. Records of treatments and death up to 10 months of age were obtained from calf ranch or dairy personnel. Risk factors for congenital infection, including dam parity and BVDV titer, were examined by use of logistic regression analysis. Effect of congenital infection on morbidity and mortality rates was examined by use of survival analysis methods. RESULTS: Fetal infection was identified in 10.1% of calves, of which 0.5% had persistent infection and 9.6% had congenital infection. Although dependent on herd, congenital infection was associated with high BVDV type 2 titers in dams at calving and with multiparous dams. Calves with congenital infection had 2-fold higher risk of a severe illness, compared with calves without congenital infection. CONCLUSIONS AND CLINICAL RELEVANCE: The unexpectedly high proportion of apparently healthy calves found to be congenitally infected provided an estimate of the amount of fetal infection via exposure of dams and thus virus transmission in the herds. Findings indicate that congenital infection with BVDV may have a negative impact on calf health, with subsequent impact on herd health.     

Body measurements of newborn calves and relationship of calf shape to sire breeding values for birth weight and calving ease

Body measurements on Angus- (n = 374) and Polled Hereford-sired (n = 438) calves were used to quantify calf shape via multivariate factor analysis, and measurements on Polled Hereford-sired calves were further used to investigate relationships between calf shape and sire expected progeny differences (EPD) for birth weight and first-calf calving ease. Calf birth weight, head circumference, shoulder width, hip width, heart girth, cannon bone circumference and length, and body length were recorded at 24 h postpartum. Sire birth weight EPD was positively associated (P less than .05) with all calf measures but only with head and cannon circumference after adjustment for phenotypic birth weight and gestation length. Thus, at constant birth weight, calves from higher birth weight EPD bulls tended to have larger cannon and head circumferences. Calving ease EPD was negatively related (P less than .05) to all calf measures except shoulder width. After adjustment for birth weight, only cannon circumference was associated with calving ease EPD, and this effect was removed by additional adjustment for birth weight EPD. Thus, at constant birth weight, bulls with higher EPD for calving ease sired calves with smaller cannon circumference, but at constant birth weight EPD, body measures were not associated with calving ease EPD. Factor analysis defined underlying skeletal width and frame components of shape (independent of birth weight) for both sire breeds. Calf shape differed among sires and was in part explained by birth weight EPD. No additional variation in shape was explained by calving ease EPD. Calf shape seemed to add no information for prediction of dystocia to that provided by birth weight EPD.     

Risk factors for high herd level calf morbidity risk from birth to weaning in beef herds in the USA

We analyzed data from a national survey of beef cow-calf producers in the USA to quantify the effects of hypothesized risk factors on herd-level calf morbidity risk from birth to weaning. The analysis included 2490 herds from 23 states. Two stepwise logistic regressions were fit to identify factors associated with ≥10% morbidity. The first model included all herds dichotomized into high-morbidity herds with ≥10% morbidity and low-morbidity herds with <10% morbidity. The second model excluded herds with between 5 and 10% morbidity, and compared >/=10% morbidity with 70% of cows and heifers calves in confinement also increased the odds of being a high-morbidity herd (OR=1.8). The population attributable fractions for dystocia and confined calving for the model including all herds dichotomized at 10% morbidity were 0.41 and 0.11, respectively. The summary population attributable fraction for both factors was 0.46.     

Characteristics of calves produced with sperm sexed by flow cytometry/cell sorting

The objectives of this study were to determine whether calves produced by sexed sperm differed from controls and to what extent the sex ratio of calves was altered by the sexing procedure. Data were collected from 1,169 calves produced from sperm sexed by flow cytometry/cell sorting after staining with Hoechst 33342, and 793 calves produced from control sperm during breeding trials between 1997 and 2001. Least squares ANOVA were completed using factors of treatment (sexed vs. control sperm), 19 management groups from 13 field trials, and calf sex. Responses analyzed include gestation length, birth weight, calving ease, calf vigor, weaning weight, abortion rate, and death rates (neonatal and through weaning). No significant difference was observed for any response due to treatment or treatment interactions (P > 0.10). Therefore, calves produced from sexed sperm grew and developed normally both pre- and postnatally. A neurological disorder was observed in four control calves and one sexed calf from one farm. No gross anatomical abnormalities were reported for any calves in the study. Differences were observed for all responses among management groups (P < 0.03 for abortions and P < 0.01 for all other responses). Heifer and bull calves differed (P < 0.001) in gestation length (278.4 and 279.6 d), birth weight (32.8 and 35.2 kg), calving ease (1.15 and 1.30), and weaning weight (233 and 247 kg). Gestation length did not affect characteristics of calves. The sex ratio at birth of calves from unsexed control sperm was 49.2% male. Sexing accuracy of X-sorted sperm was 87.8% female calves, and Y-sorted sperm produced 92.1% male calves. Flow cytometry/cell sorting can be used to preselect sex of calves safely with approximately 90% accuracy.     

Frequency of detectable serum IgG concentrations in precolostral calves

OBJECTIVE: To determine the prevalence of detectable serum IgG concentrations in calves prior to ingestion of colostrum and to assess whether a detectable IgG concentration was related to dam parity, calf birth weight, calf sex, season of calving, or infectious agents that can be transmitted transplacentally. ANIMALS: 170 Holstein dairy calves. PROCEDURES: Serum samples were obtained from calves prior to ingestion of colostrum, and serologic testing for bovine viral diarrhea virus (BVDV) and Neospora caninum was performed. Relative risk, attributable risk, population attributable risk, and population attributable fraction for calves with a detectable serum IgG concentration attributable to positive results for N caninum and BVDV serologic testing were calculated. Logistic regression analysis was used to determine whether dam parity, calf sex, season of calving, and calf weight were associated with precolostral IgG concentration. RESULTS: 90 (52.9%) calves had a detectable total serum IgG concentration (IgG >or= 16 mg/dL). Relative risk, attributable risk, population attributable risk, and population attributable fraction for calves with a detectable serum IgG concentration attributable to positive results for N caninum serologic testing were 1.66, 0.34, 0.014, and 0.03, respectively. Calf sex, calf birth weight, and season of calving were not significant predictors for detection of serum IgG in precolostral samples. CONCLUSIONS AND CLINICAL RELEVANCE: Prevalence of IgG concentrations in precolostral serum samples was higher than reported elsewhere. There was no apparent link between serum antibodies against common infectious agents that can be transmitted transplacentally and detection of measurable serum IgG concentrations.     

Influences on the occurrence of abomasal displacements in German Holstein cows]

The objectives of this study were to analyse risk factors for the prevalence of abomasal displacement in German Holstein cows. In the period from 02/01/1999 to 01/31/2000 five veterinary surgeons in Northern Lower Saxony registered all cases of abomasal displacement in German Holstein cows being under the official milk recording scheme. In total, the investigation included 160 farms and 9315 cows. An abomasal displacement was registered in 151 German Holstein cows, corresponding to a frequency of 1.6%. More than 75% of the abomasal displacements appeared during the first 30 days after calving. The left abomasal displacement (74.8%) was recorded more often than the right abomasal displacement (25.2%). Milk recording and pedigree data were supplied by the VIT (Vereinigte Informationssystem Tierhaltung), Verden, and merged with the own recordings. The influences of the calving month, the lactation number, the age at calving, the inbreeding coefficient, calving performance, duration of pregnancy, breed of calf sire, calf sire and the breeding values for the milk performance did not explain a significant part of the variation of the frequency of the abomasal displacement. Significant effects of the sire, birth of twins or even more calves and the herd were obtained for the leftsided abomasal displacement. For the rightsided abomasal displacement and for all abomasal displacements the herd effect was not significant. Heritability estimates using bivariate linear REML models were h2 = 0.043 +/- 0.012 for the leftsided abomasal displacement, and h2 = 0.007 +/- 0.004 for the rightsided abomasal displacement, respectively. Using the threshold model the heritabilities yielded estimates of h2 = 0.51 for the left abomasal displacement, and for the right abomasal displacement of h2 = 0.19, respectively.     

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.