Strategic deworming for spring-calving beef cow/calf herds

Strategic application of an anthelmintic was tested during the 1982 grazing season as part of the continued study of the epidemiology of beef cattle parasitism in central Missouri. Forty Hereford and Hereford X Simmental cow/calf pairs were assigned to 2 treatment groups. The 20 cow/calf pairs in group 1 were nonmedicated controls. After calving in mid-March, the 20 cows in group 2 were drenched with a 10% suspension of the anthelmintic fenbendazole (10 mg/kg of body weight). Ten cow/calf pairs were placed on each of four 20-acre fescue or orchard grass pastures in mid-May. Cows and calves in treatment group 2 were drenched with the 10% fenbendazole suspension (5 mg/kg) in mid-July. Body weights and fecal specimens were obtained monthly. Nematode egg counts in cow and calf fecal specimens collected monthly were significantly (P less than 0.05) lower in treatment group 2 than in treatment group 1. Numbers of larvae cultured for speciation revealed that Ostertagia ostertagi was the predominant nematode species. Developmental arrest of O ostertagi was found to be significantly (P less than 0.05) greater than zero from mid-May to mid-July. An important significant difference (P less than 0.01) was shown in body weights of calves, with the calves in treatment group 2 having a higher mean weight gain of 22.5 kg in adjusted 205-day weaning weights, and a higher mean daily gain of 0.11 kg. Weight maintenance of cows was not affected significantly by anthelmintic treatment. Nematode egg counts in monthly cow and calf fecal specimens were not significantly different between those animals on different pastures.(ABSTRACT TRUNCATED AT 250 WORDS)     

Birth weight, dystocia and calf mortality in some New Zealand beef breeding herds

Calf mortality data were summarized from four experiments, including a total of 15,694 birth records over 39 herd-years. Two experiments at Waikite and Waikeria were long-term, straightbred Angus and Hereford selection trials and the other two, at Goudies and Tokanui stations, were comparisons of 11 sire breeds mated to Angus and Herefore cows. The objective of the analyses was to study the relationship between birth weight (BW) and calf mortality for both calf sexes and for different dam age or parity groups. Overall calf death rates from birth to weaning were greater (P less than .01) from 2-yr-old than from older dams at Waikite (13.4 vs 5.3%) and Waikeria (14.7 vs 5.2%). Sex differences in death rate within 2 d of birth were small for calves from older dams. Death rate of males vs females from 2-yr-old dams were 9.1 vs 3.2% (Waikite) and 17.7 vs 10.5% (Waikeria). Mature Angus dams at Goudies had 3.7% calf deaths at birth (4.9 vs 2.4% for males vs females), a further 1.8% calf deaths to weaning and 4.6% assisted births. The BW of calves at Waikite from Angus 2-yr-old vs older dams averaged, respectively, 6.8 and 6.5% of their dam's precalving live weights. Corresponding figures for Waikeria Angus were 7.8 and 6.6% and for Waikite Herefords, 7.3 and 6.9%. Quadratic regressions revealed that, on a whole-herd basis, a small increase in BW would have no effect on total mortality at Waikeria and would decrease total mortality at Waikite; regression lines were different in shape and minimum value for calves from the two dam age groups. Quadratic models also provided an adequate fit to data from Goudies and Tokanui. There was no particular threshold BW.     

The significance of bredavirus as a diarrhea agent in calf herds in Lower Saxony]

The objective of this investigation was to determine the distribution of Bredavirus in cattle herds in Lower Saxony and to evaluate its significance as potential cause of diarrhea in calves. Fecal samples and paired blood samples of 119 diarrheic and 46 healthy calves up to two months of age were collected from herds where diarrhea of calves was a problem. Fecal samples were examined for Breda-, rota- and coronavirus by solid phase immune electron microscopy and by ELISA, for K99-positive E. coli and salmonella by microbiological methods, and for cryptosporidia in smears. Antibody titers against Bredavirus, total serum protein and serum gamma globulin content were evaluated in the blood samples. Bredavirus was found in fecal samples from 5% (n = 6) of diarrheic calves which came from four different herds, but not in healthy calves. Rotavirus (31.9%), coronavirus (18.5%) and cryptosporidia (29.9%) were detected more frequently in fecal samples than Bredavirus. In this investigation rotavirus, coronavirus and cryptosporidia were present in addition in all herds where Bredavirus was found. In contrast to the low percentage of fecal samples containing Bredavirus, antibody titers in 75% of calves confirmed the high prevalence of Bredavirus infection in the cattle population of Lower Saxony.     

Bovine respiratory syncytial virus (BRSV) pneumonia in beef calf herds despite vaccination.

The present report describes the clinical, pathological, serological and virological findings in calves from 2 larger Danish beef herds experiencing outbreaks of pneumonia. The calves had been vaccinated with an inactivated bovine respiratory syncytial virus (BRSV) vaccine 2 months prior to the outbreak. The clinical signs comprised nasal discharge, pyrexia, cough and increased respiratory rates. A total of 28 calves died in the 2 herds. The laboratory investigations revealed that BRSV was involved and probably initiated both outbreaks. Furthermore, the serological results suggested that the vaccine induced only sparse levels of antibodies probably due to the presence of maternally derived antibodies at the time of vaccination. Necropsy findings in 5 calves revealed changes typical for infectious pneumonia with involvement of BRSV. In conclusion, vaccination of calves against BRSV in 2 Danish beef herds failed to protect the calves against severe or even fatal BRSV mediated respiratory disease 2 months later.     

Reproductive efficiency and calf survival in Ontario beef cow-calf herds: a cross-sectional mail survey.

A survey of the efficiency of production of Ontario beef cow-calf herds was conducted using a stratified systematic random sample of Ontario producers. In general, about 87% of females exposed to breeding produced a live calf and 6% of these died before reaching four weeks of age. The herd to herd variation in these rates was quite large, the coefficient of variation being about 17%. The stillbirth rate was 1.7% and the abortion rate 1.2%. In general, herds in northern Ontario and herds whose owners kept breeding and calving records, had reduced livebirth rates, the latter probably reflecting accuracy of data. Herds with a restricted (less than three months) breeding season had increased livebirth rates. Herds using injectable vitamins ADE, and prophylactic antibiotics, had increased neonatal losses. Herds with a restricted calving season (less than or equal to 3 months) and/or feeding free choice salt to cows had decreased neonatal losses. Herdsize and calf mortality rate were directly related, but this did not appear to be due to increased density of cows at calving time. In herds, where calving occurred during the spring, using scour vaccines in calves was associated with increased calf mortality.     

Prevalence of calves persistently infected with bovine viral diarrhea virus in beef cow-calf herds enrolled in a voluntary screening project

OBJECTIVE: To report the prevalence of bovine viral diarrhea virus (BVDV) in calves and calf groups (ie, calves from the same farm) in beef breeding herds and evaluate the ability of biosecurity risk assessment questionnaires to identify calf groups with positive results for BVDV. DESIGN: Nonrandom survey. ANIMALS: 12,030 calves born in spring from 102 operations. PROCEDURES: Cow-calf producers that voluntarily enrolled in a screening project submitted ear notch specimens from calves and answered a 29-question survey instrument. Ear notch specimens were tested for BVDV with an antigen-capture ELISA (ACE), and ear notch specimens with positive ACE results for BVDV were immediately retested by performing immunohistochemistry (IHC). Follow-up testing, 3 to 4 weeks after initial positive ACE results, was done by use of a second IHC test and virus isolation on a subsequently submitted ear notch specimen from the same calves to identify those that were persistently infected (PI). RESULTS: 102 producers submitted ear notch specimens for BVDV screening. Initially, 24 of 12,030 calves had positive ACE results for BVDV. A second ear notch specimen was submitted for 20 of these 24 calves. Of 20 retested calves, 12 had positive ICH results for BVDV, confirming PI status. The 12 PI calves came from 4 calf groups (3 singletons and 1 calf group with 9 PI calves). CONCLUSIONS AND CLINICAL RELEVANCE: Prevalence of BVDV in calf groups was low, and questions designed to identify high-risk biosecurity behaviors had little value in identifying calf groups with positive results for BVDV.     

Gross postmortem and histologic examination findings from abortion losses and calf mortalities in western Canadian beef herds

Production losses from abortions, stillbirths, and early calf mortality were described for the 2002 calf crop in 203 beef herds in western Canada. A total of 1689 calves were examined. A summary diagnosis was reported for 64% of aborted calves, 78% of stillborn calves, 88% of neonatal calves, and 94% of the calves > 3 d of age. Diagnoses for aborted calves included: thyroid gland lesions, pneumonia, developmental anomalies, placentitis, and myocardial necrosis or myopathy. For stillborn calves, diagnostic findings included: dystocia, thyroid gland lesions, myocardial necrosis or myopathy, developmental anomalies, and skeletal myopathy or necrosis. The most common diagnoses for neonatal calves (≤ 3 d) were: pneumonia, skeletal myopathy or necrosis, myocardial necrosis or myopathy, accident or trauma, and septicemia. For older calves (3 d to 3 mo), the most common diagnoses included: starvation, abomasal ulcer or perforation, enteritis or colitis, pneumonia, and intestinal volvulus, obstruction, or perforation.     

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.     

Incidence of rotavirus in beef herds in Argentina

Faecal samples were collected from 177 diarrhoeic and 40 healthy calves from 19 farms in Buenos Aires State, Argentina during 1984 and 1985. Samples were examined for rotavirus by enzyme-linked immunosorbent assay (ELISA) and polyacrylamide gel electrophoresis (PAGE) of their genomic RNA segments. Rotavirus was found in 95 samples of diarrhoeic calves (53 per cent) and in three healthy calves (7 per cent). All positive samples were tentatively classified as group A on the basis of electropherotype and ELISA test reactivity and exhibited 18 different genomic electropherotypic patterns.     

Pathophysiology of neonatal calf diarrhea

Neonatal calf diarrhea caused by bacterial enterotoxins, bacterial or parasitic-induced inflammation, or virus-induced villous atrophy leads to intestinal hypersecretion, malabsorption, or both. Mechanisms of secretion and malabsorption differ depending on the agent, suggesting that different modes of treatment must be employed to be effective. Currently, oral rehydration solutions and the pharmacologic blockade of secretory processes are being evaluated in these various diseases.