Bovine rotavirus C (RVC), bovine coronavirus (BCV), and coccidia were detected in a herd of calves with diarrhea at a public ranch in Tochigi Prefecture from May to June 2016. A significant increase in anti-RVC and -BCV titers were also observed in the calf herd. Moreover, 100 serum samples collected at 12 farms in Tochigi Prefecture were subjected to an indirect immunofluorescence assay to investigate bovine RVC antibody prevalence in dairy calves from a variety of young age groups. Antibodies against RVC were detected at 83% of the farms. Our data also showed that about 50% of calves from 12 to 23 months of age were infected with bovine RVC. In this study, we demonstrate that bovine RVC is an important causative agent of diarrhea in adult cows as well as calves.

To prevent bovine leukemia virus (BLV) infection among cattle on a dairy farm, we identified calves that were infected with BLV using nested-PCR from May 2015 to December 2016. Twenty-five calves born from BLV-infected cows were examined during the birth month and the following month. Among these, 2 calves were identified as being infected with BLV. All calves under 6 months of age were examined 3 times for periodic surveillance of BLV infection, and 2 of 35 calves were identified as being infected. The 4 calves infected with BLV, with ages ranging from 19 days to 5 months, were culled from the farm. We implemented precautionary measures to avoid horizontal transmission of BLV in the herd of growing cattle on the dairy farm from May 2015. We evaluated the rate of conversion from seronegative to seropositive in the herd from June 2014 to May 2015 and from May 2015 to April 2016. The rate of conversion decreased from 64.7% to 12.5% (P＜0.05). The seroprevalence rate in the herd decreased to 0% in December 2015. Our study results indicate that identification of BLV-infected calves using nested-PCR can be a useful approach to prevent BLV infection on dairy farms and reduce breeding costs for growing calves.

We devised a new method of determining the incident beam angle for the bisecting angle technique in canine dental X-ray examinations. In this method, the X-ray beam is directed along the bisector of the angle between the extra-oral extension of the film plane and the long axis of the tooth. We conducted a validation study using a model consisting of a skull and a mock film to compare three methods of the bisecting angle technique: our newly devised method, the conventional method, and another recently proposed method. Each method was evaluated for simplicity, which was defined as the time that it takes to determine the incident beam angle, accuracy in the rate of image size distortion, and precision as its variability. These parameters were compared among the three methods on the first trial, as well as on subsequent trials to see if a learning curve was involved. Our method showed the shortest time for beam angle determination, accuracy similar to that of the other methods, and little variability, suggesting that it may be easy to understand and simple to use even for beginners.

Our previous studies showed that the prevalence and bacterial concentration of Campylobacter were lower in chickens given special feed (B chickens) than in those given ordinary feed. We further investigated the colonization of Campylobacter among B chickens in 34 farms and found that only 6 farms were positive for Campylobacter. When the farms were evaluated based on hygiene practices, 17 were “good”, 11 were “intermediate”, and 6 were “poor”. Of these, 1 (6%), 2 (18%), and 3 (50%) respectively were positive for Campylobacter. Analysis of the relationship between the contaminated farms and their hygienic levels revealed a significant difference between farm contamination rates (odds ratio: 5.30, P = 0.019, good vs. poor). This suggests that there are potential beneficial effects of good hygiene practices for decreasing Campylobacter contamination risk at farms raising B chickens, where the Campylobacter infection rate appears to be lowered with the provision of special feed.