Short communication: Long-term survival of flag eartags on an Israeli dairy farm.

Two-plated self-piercing eartags were first developed in the 19th century, but information on their retention rates is scarce. A method is presented that facilitates estimation of eartag retention rate by using a random sample of cows that initially had 2 tags (1 on each ear) placed for identification and at least 1 of which survived. Striving to adopt the European Union standard for cattle ear tagging, the Israeli veterinary service conducted a field test to evaluate the performance of plastic eartags under the conditions of a typical Israeli dairy farm. The initial sample (n=900 cows) was tagged on a single farm. Retention rates were estimated based on the ratio between the observed numbers of cows with 1 or 2 eartags in the surviving group (n=97 cows). Based on this long-term (>3 yr) field test, the highest yearly retention of flag eartags (0.89±0.03) was lower than expected (0.98). Tag design and on-farm management were key factors affecting tag retention. A better design of the feedline yoke system in the feeding area, avoiding slits that can entangle the eartags, would help increase tag retention.

Appearance of skin lesions in cattle populations vaccinated against lumpy skin disease: statutory challenge.

The ultimate goal of a vaccine is to protect vaccinated animals against re-exposure to the same pathogen and provide sterile immunity. However, a cutaneous clinical manifestation appeared, following re-exposure of cattle that had been vaccinated with the RM65 strain, to LSDV infection during an epidemic in 2006-2007. Four thousand six hundred and seven vaccinated cows entered the study after being re-exposed to LSDV infection. Of them, 513 (11%) presented lumps, and there was a marked difference between the proportions of dairy and feedlot animals that were affected: 146 out of 3517 and 367 out of 1090 (6.6 and 33.7%, respectively). This data suggests that the potency of the vaccine need to be re-assessed for beef cattle.

The NSP immune response of vaccinated animals after in-field exposure to FMDV.

The aim was to examine the immune response (IR) to non-structural proteins (NSPs), in order to assess the validity of the detection of antibodies to NSPs as a means of diagnosing foot and mouth disease (FMD infection) infection when vaccinated populations are in close contact with clinically sick animals. The study was performed during FMD outbreaks in Israel in January 2004; the IR was examined in vaccinated dairy and feedlot cattle herds under natural field exposure to FMDV, and in vaccinated and unvaccinated sheep flocks. During the 2004 outbreaks, clinical signs were age-related and were noted only among imported calves, although they had been vaccinated; such signs were not found among the local dairy cattle populations. The NSP IR among the feedlot cattle that had been vaccinated more than 4 months prior to the in-field exposure was 86%, compared with only 30% among those feedlot cattle that had received one dose of vaccine less than 4 months before the field exposure. The prevalence of NSP IR indicates that animals vaccinated once, less than 4 months prior to exposure, were clinically resistant to FMDV infection, although possibly still susceptible to subclinical infections, whereas those vaccinated more than 4 months prior to the in-field exposure presented clinical manifestations. This situation is unlikely to occur among repeatedly vaccinated livestock; these remained refractory to FMD exposure, as reflected in the absence of clinical manifestations and a relatively low prevalence of NSP IR compared with that in imported calves.

An unusual outbreak of malignant catarrhal fever in a beef herd in Israel.

Malignant catarrhal fever (MCF. corrizza contagiosa) is an invariably fatal communicable disease in cattle, whose causative agent is the ovine herpes virus-2, or the alcelaphine herpes virus-1. In one feed-lot family farm, 34 calves out of 100 became ill at the rate of one to four calves per week, and all of them subsequently died over a period of 4 months. Most of the initial cases were manifested clinically as the head and eye form, but most of the entire clinical spectrum of forms (the respiratory, intestinal and nervous forms) characteristic for MCF were observed as this epidemic progressed. Very few calves died without showing any specific signs of MCF. Pathological examinations revealed characteristic obliterative arteriovasculitis in the brain of calves with nervous signs, typical of MCF. Polymerase chain reaction (PCR) testing revealed 100% homology between the 238 bp hemi-nested PCR fragment and the ovine herpes virus-2 sequences. Based on the clinical signs, epidemiological data, pathological, and histopathological findings, and the PCR results, it was concluded that MCF occurred on the farm. The fact that sheep and goats were housed in close proximity on the same farm reinforced this diagnosis.