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Bovine leukemia virus (BLV) is horizontally transmitted among cattle through infected blood. This 3-year field study (2013–2016) aimed to confirm the potential of the blood-sucking stable fly as a risk factor of BLV transmission and to determine the efficacy of vector control on preventing the transmission of BLV. The BLV-positive conversion rate during summer was higher than that during winter in a model dairy farm, where many stable flies were observed during the summer. After fly nets were fixed onto the barn to prevent fly invasion, the BLV-positive conversion rate during the summer was significantly decreased compared with that in the absence of fly nets (P<0.01). These findings suggest that vector control using a fly net may inhibit BLV transmission.

Background: Bifidobacterium breve is widely used as a probiotic in preterm infants and children with congenital surgical conditions, however, some cases of probiotics-induced bacteremia have been reported recently. Objectives: To examine the clinical and bacteriologic features of Bifidobacterium breve bacteremia caused by a probiotic (BBG-01) in term and preterm infants. Methods: We included 298 patients who were admitted to the neonatal intensive care unit of Miyagi Children's Hospital and were given BBG-01 as a probiotic within the period June 2014 to February 2019. We experienced six cases of B. breve bacteremia and assessed their features retrospectively. Results: The incidence rate of B. breve bacteremia in our hospital was 2% (6/298), higher than reported previously. The median age at onset, corrected age, and weight of the patients was 8 days (range: 5-27 days), 35 weeks (range: 26-39 weeks), and 1,940 g (range: 369-2734 g), respectively. The bacteremia triggers were gastrointestinal perforations in two cases, food protein-induced enterocolitis syndrome in two cases, adhesive ileus in one case, ileal volvulus in one case, and aspiration pneumonia following esophageal atresia repair in one case. B. breve was detected on blood cultures after a median of 5 days 13 hours (range: 4 days 18 hours-9 days 13 hours). No patient demonstrated serious symptoms, such as septic shock. All patients received antibiotics and recovered without any sequelae. Conclusions: Ileus and intestinal mucosal damage, such as enteritis, can cause B. breve bacteremia. The incidence of B. breve bacteremia may be higher than reported previously and detection via culture may require a longer time than typically needed for more common bacteria. It is associated with a good prognosis.

The association between blood calcium levels and electrocardiographic variables was compared in 137 normal parturient and 36 peripartum recumbent Holstein cows to determine whether hypocalcemia in peripartum dairy cows can be rapidly diagnosed using electrocardiograph. Inverse of STc (ST peak interval/SS interval0.5) and blood ionized calcium or serum calcium concentrations were strongly correlated, and both correlation coefficients were 0.81 (P<0.001). The 95% prediction interval indicated that cows with STc >0.385 ± 0.001 sec are very likely to be hypocalcemic (blood ionized or serum calcium concentrations of <0.9 mmol/l or <7.5 mg/dl, respectively). These findings indicate that hypocalcemia in parturient cows can be non-invasively estimated using the STc.

We previously reported the possibility of using the electrocardiogram variable to estimate blood calcium (Ca) concentration in dairy cows based on the strong positive correlation between the blood Ca concentration and the inverse of the corrected ST peak interval (STc −1 ).To improve the accuracy of the estimation of blood Ca concentration, we investigated the relationship between blood Ca concentration and STc −1 for each postpartum day and available variables other than STc −1 . We measured multiple variables (milk yield, calving number, age, body temperature, etc.), including serum total Ca concentration (tCa), blood ionized Ca concentration (iCa) and STc −1 in 462 Holstein cows on days 0, 1, 2, 3, 5, and 7 postpartum. A very high correlation was observed between iCa and tCa. The association between tCa and STc −1 for each postpartum day had a high coefficient of determination of 0.61-0.79 postpartum 0-2 days but decreased after the third day. In the investigation using the data from postpartum days 0-2, STc −1 , heart rate interval, calving number, and age were highly correlated with tCa.In addition, a multiple regression equation was obtained with tCa as the objective variable and STc −1 and calving number as explanatory variables. The estimation accuracy was improved as compared with the simple regression equation using only STc −1 as the explanatory variable. This multiple regression equation was used for 11 cows suspected of having hypocalcemia, and it was able to correctly detect cows requiring early treatment, except for one cow.

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To clarify the mechanisms underlying the development of displaced abomasum (DA), we repositioned DA in 12 cows by rolling and observed the course of redisplacement using X-ray fluoroscopy. Displacement of the abomasum was observed to follow three patterns: displacement to the left side of the abdominal cavity through the gap formed at the reticulum, atrium of the rumen and ventral sac of the rumen (n=7); displacement to the left side after cranial movement along the diaphragm (n=3); displacement to the right side after cranial movement along the diaphragm (n=2). These differences were considered to be associated with the rumen volume. To the best of our knowledge, this is the first study reporting the visual observation of the course of DA in dairy cows.

Background Salmonella enterica in cattle has long been problematic and suspected to be transmitted by wildlife in Tokachi, Hokkaido, a major cattle farming area in Japan. Understanding the role of wildlife in S. enterica transmission would be helpful for developing control strategies of bovine salmonellosis. Objectives We aimed to elucidate the possibility of S. enterica transmission between sympatric wildlife, including raccoons and crows and cattle, in Tokachi from 2008 to 2018 by analysing S. enterica detection records, and the genetic relatedness of serotypes shared between wildlife and cattle. Methods S. enterica detection records were based on the results of a field survey and existing cattle records at relevant organisations, including clinical reports, a monitoring survey and quarantine for introduced calves at growing farms and public calving farms. S. enterica was identified by polymerase chain reaction assay and serotyped by agglutination assay. The detection records were organised chronologically to investigate whether common serotypes in wildlife and cattle were detected in the same year. The isolates corresponding to detection records were assessed for their genetic patterns by pulsed‐field gel electrophoresis. Results The prevalence of S. enterica in raccoons and crows was 10.7% (17/159) and 5.7% (55/967), respectively. The following serotypes were detected from both wildlife and cattle: Braenderup, Dublin, Infantis, Mbandaka, Montevideo, 4,[5],12:i:‐ and Typhimurium. Genetically similar isolates for S. Braenderup, S. Dublin, S. Montevideo and S. 4,[5],12:i:‐ were detected from both species in the same year. Conclusions Our long‐term retrospective observations supported that S. enterica was shared between wildlife and cattle. Wildlife invasions should be controlled at farms to prevent inter‐species transmission of S. enterica from livestock farms.