Effects of fallen snow on the voluntary intake and grazing behavior of Hokkaido native horses in winter woodland with underlying Sasa senanensis

The intake, digestibility, and grazing behavior of Hokkaido native horses were investigated in winter woodland with underlying Sasa senanensis. Twenty Hokkaido native horses were grazed in a woodland (8.52 ha) for 14 days in December (snowy; 20 cm of snow fall) and in November (non‐snowy) of the next year. Three mares (360 kg of average bodyweight) were used in each experiment. The fecal collection, used to investigate the intake and digestibility by the double‐indicator method, and behavioral observations were carried out for 24 h on the 6th day in each experiment. During the snowy and non‐snowy periods, the dry matter intakes of sasa foliage were 7.3 and 9.6 kg/d, respectively, which is 2.1 and 2.7% when expressed as a percentage of bodyweight. The apparent digestibility of nutrients and energy released during the snowy and non‐snowy periods were similar. The proportions of digestible energy intakes to maintenance requirement in the mares were 119 and 164% during the snowy and non‐snowy periods, respectively. Their bodyweight remained constant during the non‐snowy period; however, a slight loss in their bodyweight was observed during the snowy period. The duration of grazing on sasa foliage was 416 and 544 min/d during the snowy and non‐snowy periods, respectively, the daily grazing area of the mares during these periods was 2.0 and 5.1 ha, respectively. In other words, the area during the snowy period was smaller than that during the non‐snowy period (P < 0.05). Fallen snow, even with a depth of approximately 20 cm, inhibited the grazing behavior and intake of sasa foliage by Hokkaido native horses grazing in winter woodland pasture.     

The inhibitory effect of interferon gamma and tumor necrosis factor alpha on intracellular multiplication of Neospora caninum in primary bovine brain cells

Primary culture of bovine brain cells was examined for its susceptibility to Neospora caninum infections, and this model was used to investigate the effects of bovine interferon gamma (IFN-gamma) and tumor necrosis factors alpha (TNF-alpha) on tachyzoite growth. Tachyzoites of N. caninum grew well in this culture, and tachyzoite growth in astroglia and microglia were confirmed by immunocytochemical staining. IFN-gamma inhibited the tachyzoite growth, and this inhibition was not reversed by the addition of nitric oxide antagonist. TNF-alpha, to a lesser extent, also inhibited the tachyzoite growth. Th-1 type cytokines may play an important role in host defense mechanisms in N. caninum infection.     

Pathological and immunological findings of athymic nude and congenic wild type BALB/c mice experimentally infected with Neospora caninum.

Neospora is a cyst-forming coccidian parasite that causes abortions and neuromuscular disorders in a wide variety of mammals. Japanese bovine isolate JPA1 was inoculated intraperitoneally into BALB/c nu/ nu (athymic nude) and BALB/c (congenic wild type) female mice to examine the distribution of parasites and resistance mechanisms to Neospora infection. All the athymic nude mice died within 28 days after intraperitoneal injection of 2 x 10(5) JPA1 tachyzoites, whereas all the congenic wild type mice survived without exhibiting any clinical signs. Tachyzoites were identified in the uterus and pancreas and later spread to many other organs. Most tachyzoites identified in the necrotic foci were localized in the epithelium of the venules and capillaries. Nude mice developed high level of serum interferon-gamma and interleukin-6 as infection proceeded. Inflammatory response to Neospora infection might be mediated by Th1-type dependent cellular immunity.     

Influence of uterine inflammation on the estrous cycle in rats

To investigate how uterine inflammation affects ovarian activity in rats, endometritis was induced and changes in the length of estrous cycle and serum concentrations of estradiol-17beta (E(2)) and progesterone (P(4)) were examined. A suspension of Staphylococcus aureus (bacterial solution) or iodine solution was infused into the uterine lumen at various estrous phases. When the bacterial solution was infused at estrus, metestrus, or the first day of diestrus, the following diestrus continued for 5 to 12 days. In the case of the iodine solution, regardless of the estrous phase of the infusion, the following diestrus continued for approximately 6 days. E(2) concentration after infusion of each solution did not fluctuate largely and remained at a low concentration (around 5 pg/ml). P(4) concentration was high (35-45 ng/ml) on the day following infusion, but decreased rapidly to base line values within a few days and remained thereafter at a low level (around 5 ng/ml). It is assumed that the endometritis caused by biological or chemical stimulation raises the concentration of P(4) to depress gonadotrophic hormone secretion, and hence this high P(4) concentration might inhibit the growth of ovarian follicles.