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Bovine foamy virus (BFV) is endemic in many countries, but has not been reported in Japan. A syncytium-forming virus was isolated from peripheral blood leukocytes of clinically healthy cattle on a farm in Kanagawa prefecture during a periodic epidemiological survey of viral diseases. The isolate was propagated in primary fetal bovine muscle cells and subsequently passaged in Madin–Darby bovine kidney cells. Since the isolate appeared to be distinct from the viruses with syncytium-forming ability previously isolated in Japan, we attempted to identify it using genomic analyses and electron microscopy. A phylogenetic analysis revealed that the isolate belongs to the bovine foamy virus cluster and is highly similar to a BFV strain isolated in China. A sero-epidemiological survey was performed using agar gel immunodiffusion test with the isolated virus as the antigen, and five of the 57 cattle tested were found to be seropositive.

ABSTRACT. In the present study, the effect of 4-day fasting on steroid hormone metabolism in the liver and secretion of LH was examined in cows. Six non pregnant, dry Holstein cows were used. The estrous cycle was synchronized in all cows using CIDR-Ovsynch. Cows were allocated to a control group (n=3) and a fasting group (n=3). In the fasting group, cows were fasted for four days from day -4 to day -1 (day 0=day of 2nd GnRH injection) but otherwise were fed ad libitum. The experiment was repeated in a crossover design after an interval of about one month. The peripheral progesterone (P 4 ) concentration in the fasting group was significantly higher than in the control group on day -1 and 0. The peripheral estradiol-17 concentration in the fasting group was also significantly higher than in the control group on day -1 and 0. The portal vein P 4 concentration in the fasting group was significantly higher than in the control group. On day 0, there was no difference in LH secretion between groups. The mean percentages of lipid droplets in liver cells in the fasting group were significantly higher than in the control group on day 0. These results suggest that short-term fasting leads to reduced hepatic steroid hormone metabolism by accumulation of fat in the liver, which causes high peripheral steroid hormone concentrations. Gonadal steroid hormones, such as progesterone (P 4 ) and estradiol-17 (E 2 ), are metabolized primarily in the liver and partially in the kidney and intestine before being excreted into the urine and feces [4]. Peripheral concentrations of these hormones are therefore largely affected by their metabolic clearance rates in the liver, which increase with liver blood flow. In fact, the amount of P 4 flowing into the liver has been directly associated with the plasma P 4 level [12]. Feed intake is another factor that affects steroid metabolism because it is directly correlated with the portal blood flow rate in sheep [12]. Lactating cows, which are maintained with high dry matter intake, have increased hepatic blood flow resulting in 2.3 times higher metabolic clearance rates of E 2 and P 4 compared to non lactating cows [16]. This increased metabolism leads to decreased levels of peripheral E 2 and P 4 , which are associated with decreased reproductive efficiency, such as decreased conception rate, increased pregnancy loss, increased multiple ovulation rate and decreased estrous behavior [16]. Thus, feed intake can affect gonadal steroid hormone secretion by alterations in the liver blood flow. Feed intake is also considered to affect LH secretion from the pituitary gland via the feedback action of steroid hormones.Periparturient dairy cows are in a state of negative energy balance, which results in decreased liver function due to fatty liver. Fatty liver, too, is associated with poorer reproductive performance such as decreased conception rate and longer calving intervals [2]. In the present study, the effect of short-term fasting on steroid hormone metabolism in the liver was investigated by c...

The prevalence of bovine foamy virus (BFV) infections in cattle on farms in the Kanto region of Japan was determined using agar gel immunodiffusion (AGID) test and polymerase chain reaction (PCR). Six out of 20 farms contained BFV-positive cattle. Furthermore, 16.7% (91/545) of all cattle tested positive for BFV. This suggested that BFV-infected cattle are widely prevalent in Japan. Positive results for BFV infection were consistent between AGID and PCR tests. Additionally, we tested for bovine leukemia virus infections at nine farms, primarily those containing BFV-infected cows. At each farm, the infection rate of BFV was lower than that of bovine leukemia virus. Further, cattle that were PCR-positive but antibody-negative, indicating immune tolerance to BFV, were not detected.

In the present report, the incidence and prognosis of ovarian diseases were evaluated in correlation to the grades of the fatty livers (FL). 233 animals were diagnosed with a FL, based on fat deposition of >10% into the hepatic parenchyma obtained from liver biopsy, and were eventually cured of the FL. These 233 animals were classified into mild group (n=99: hepatic fat deposition rates ranging from 10 to <30%), moderate group (n=56: hepatic fat deposition rates ranging from 30 to <60%) and severe group (n=78: hepatic fat deposition rates of >60%). The incidence of ovarian diseases and the culling rate were, respectively, 40.0% and 10.0% in mild group, 58.3% and 37.5% in moderate group, and 84.9% and 69.7% in severe group. The incidence of ovarian diseases and the culling rates in severe group were significantly (P<0.05) higher than those in mild and moderate groups. It was, therefore, concluded that the elevated incidence of ovarian disease and culling rates tend to be dependent on the higher severity scores of the fat deposition rates in dairy cows with FL and that cases with severe FL, with a fat deposition rate of 60% or higher, were greatly associated with death and culling.