Grazing Use of Native Pastures by Beef Cattle in Japan : Recent Researches on Plant-animal Interactions in Native Pastures

Understandings of plant-animal interactions are vital for adequate control of vegetation and animal conditions and sustainable use of the natural resources in grazing systems. In this paper, studies of plant-animal interactions that were carried out in native pastures at the Kawatabi Field Science Center (KFSC) in Tohoku University were reviewed. 1. Although forage quality of native grasses is known to lower than that of grasses in sown temperate pastures, fresh and masticated native grasses have higher ruminal degradability than dried and ground ones, indicating the importance of using fresh samples when estimating the nutritive value and ruminal digestibility. Native pastures are also suggested to supply more copper to animals than sown pastures. 2. The indigenous vegetation of the KFSC is composed of 61-80 plant species, of which cattle graze upon 44-75 species. Among these species, Miscanthus sinensis, Zoysia japonica and Sasa palmata are especially valuable for cattle grazing in Japanese native pastures. A new technique using plant opal phytoliths as markers is effective to obtain information on intake of individual plant species. 3. Studies of grazing impacts of cattle on plant succession are also essential to the grazing system in a native pasture. In the KFSC, shrubs such as Weigela hortensis have been increasing in M. sinensis pastures by cattle grazing, due to a decline in aboveground biomass and seed production of M. sinensis, and the removal of litter on the ground. Seed dispersal by grazing animals also exerts significant effects on vegetational change. 4. Beyond these studies, estimating environmental impacts of grazing on such ecosystems will require long-term investigations and quantification of nutrient flow in native pastures, including soil and soil microorganisms as variables

Effect of change in body mass index on morbidity in non-obese university graduates.

To establish the actual serial changes in body weight in Japanese people and to elucidate the influence of changes in BMI on morbidity, we conducted a historical cohort study of university graduates from 1955 to 1990 using questionnaires and BMI data. The subjects of this study were 3,675 university graduates aged 26-62 years in whom BMI was determined at the time of enrollment in the university (Pre-BMI), 5 to 40 years earlier. Morbidity (one or more system diseases or obesity-related system diseases) was analyzed according to current age, sex, current BMI, deltaBMI (difference between current BMI and pre-BMI), and various lifestyle variables. The proportion of overweight subjects at enrollment to university was higher in recent male students compared to old students, but not in female graduates, and the BMI in both genders increased progressively after graduation, especially in recent male graduates. Pre-BMI correlated negatively and significantly with deltaBMI. The percentages of obese (BMI > or = 30 kg/m2) males and females were 1.6% and 0.5%, respectively, and high morbidity was observed in 56.1% and 42.2% of males and females, respectively. Stepwise regression analysis showed that in subjects with normal BMI at enrollment, prospective morbidity was dependent on ABMI in addition to age. Our results indicate that in subjects with normal body weight, prospective morbidity is determined by increment of ABMI, and suggest that maintenance of BMI at the late adolescence level is an important factor in preventing future disease.</p

Heterogeneous Impacts of Grazing Animals and Vegetational Change in Japanese Native Pastures

Defoliation, defecation and trampling are the major modes whereby grazing animals give impacts on vegetation. Due to the uneven distribution, such grazing behavior can have profound effects on vegetation. For extensive grazing systems in native pastures, understandings of the plant-animal interaction are vital for adequate control of vegetation and animal conditions and sustainable use of natural resources. This paper reviews recent studies of the grazing impacts on vegetation in Japanese native pastures. Most of the studies were carried out in the Kawatabi Field Science Center (Kawatabi FSC), Tohoku University. 1.Native pastures in the Kawatabi FSC are composed of 61-155 plant species, of which cattle graze upon 26-76 species. Among these species, Miscanthus sinensis (Japanese plume-grass) was the most frequently grazed by cattle. The spatial distribution of available forage is a major factor affecting diet selection and consumption of cattle. Such selective grazing results in significant reduction of M. sinensis in native pastures. 2.Seed dispersal of plants by defecation of grazing animals can also result in significant vegetational change. Recent studies have shown that Carex spp. is the major plant whose seeds are dispersed by defecation of animals rotationally grazed in a native and a sown pasture. The mechanisms of the seed dispersal and its possible effects on vegetational succession are discussed. 3.Heavy trampling is known to degrade vegetative ground cover. Our research has shown that trampling by cattle promotes the invasion of a shrub, Weigela hortensis into Miscanthus-dominant pastures. Because the seeds of W. hortensis are light sensitive germinators, trampling by removing ground cover promotes its seed germination. These findings provide new perspectives on plantanimal interactions in Japanese native pastures and help estimate the impact of animals on plant succession. They also contribute to efforts to ensure sustainable grazing use of pastures

Casting of MOD inlay using rings with holes on both sides : 12～18 wt%Au-20～26Pd-14.48～26.48Cu-40Ag-1.57Zn-0.02Ir alloys

Using a casting ring with openings on both sides and a water-absorbent polymer, heterogeneity is maintained in a single casting and a precise MOD inlay can be produced. We produced 9 different kinds of gold-silver-palladium (Au-Ag-Pd) alloys by changing the ratio of palladium, gold, and copper and investing them, and changing parameters such as the angulation of the casting ring openings and the water:powder ratios to produce MOD inlay castings. We measured the expansion and shrinkage percentage of the castings in both the buccolingual and mesiodistal directions. From this experiment, we learned that precise MOD inlay castings can be produced using rings with 240° openings when invested in a thick mix having a standard water:powder ratio or using rings with 200° openings when invested in a thick mix having a water:powder ratio for a 12wt%Au-20〜26Pd-20.48〜26.48Cu-40Ag-1.5Zn-0.02Ir alloy

α-Naphthylisothiocyanate (ANIT) Induced Cholestasis in Rats

In order to distinguish the disorder of bile acid and cholesterol metabolism in α-naphthylisothiocyanate (ANIT)-induced cholestasis, we examined changes in bile acid levels and compositions in bile, serum, feces and urine, as well as cholesterol levels in bile, serum, liver and feces in Wistar male rats (10-13 weeks) after a single oral administration of 100 mg/kg of ANIT. The bile flow and the biliary secretions of cholesterol, phospholipids and bile acids markedly decreased on days 1 and 2 but increased over the normal values on day 4 and then returned to the normal ranges. The fecal excretion of bile acids decreased after the treatment and remained low by day 4 but markedly increased thereafter. The urinary excretion of bile acids changed almost in parallel with serum bile acid level, increasing to 37 mg/day on day 2, 28 mg/day on days 3-4 but to a trace on days 5-6. The urinary bile acids on day 2 mainly consisted of cholic acid while those on days 3-4 and biliary bile acids on day 4 were mostly β-muricholic acid. The serum cholesterol level markedly increased maximally on day 2 and decreased thereafter. The fecal excretion of sterols, cholesterol and coprostanol, decreased on days 1-2 but rather increased thereafter. These data suggest that the cholestasis induced by ANIT is very similar to that in bile duct ligated rats for a short period but not to those ligated for long periods. In addition, the present data suggest that the bile acid independent bile flow is impaired and the daily synthesis of bile acids, especially β-muricholic acid, is increased in the ANIT induced cholestasis

Aerobic and Anaerobic Biotransformation of Bile Acids by Escherichia coli (III)

The oxidation/reduction reactions of bile acids by Escherichia coli (E. coli) K-12 were examined in both Davis and brain-heart infusion (BHI) media under aerobic and anaerobic conditions. The pH in the Davis medium changed by almost the same amount, around pH 6.5?7.0 in both aerobic and anaerobic cultures, but the pH in the BHI medium was different in both cultures, that is, about pH 9.0 in the aerobic culture but only about 6.5 in the anaerobic culture. The growth curve of E. coli in the Davis medium showed a similar pattern in both conditions. Cholic acid (CA) was oxidized to 3α12α-dihydroxy-7-oxo-5β-cholanoic acid (3α12α7=O) in both cultures, but the reaction in the anaerobic culture was somewhat slower than that in the aerobic culture. On the other hand, reduction of 3α12α7=O to CA did not occur in the aerobic culture, but about 10% reduction was observed in the anaerobic culture after 4 days. These data suggest that the oxidation/reduction reaction of E. coli was oxidative in aerobic culture but reductive in anaerobic culture and these characteristics were not due to the changes in the pH of the medium. The reactions of CA and glycocholic acid to crude 7α-HSDH prepared from E. coli were examined and it was found that both free and conjugated CA as a substrate for the 7α-HSDH showed similar Km values

Internal Standard Compounds for Quantitative Determination of Bile Acids by Gas Chromatography

Gas chromatography is well recognized as a useful tool with several advantages for the analysis of bile acids as well as various compounds. In gas chromatographic analysis, bile acids in an analytical sample are subjected to a number of complicated procedures involving many steps such as extraction, fractionation, solvolysis, hydrolysis, derivatization and injection to the gas chromatograph. These procedures result in the loss of bile acids in the analytical sample. The addition of suitable internal standard compound(s) into the analytical sample prior to the extraction of bile acids is indispensable for an accurate determination of bile acids. There are two methods for the quantitative determination of bile acids in a biological sample by gas chromatography: one is the determination of total bile acid amounts in the sample. The other is the determination of bile acid amounts in each fraction after group separation of bile acids in the biological sample using an ion exchange gel column. The addition of 7β,12α-dihydroxy-5β-cholanoic acid or 7β,12β-dihydroxy-5β-cholanoic acid as an internal standard compound is useful for the former method. On the other hand, the addition of 7β,12β-dihydroxy-5β-cholanoic acid, glyco-7α,12α-dihydroxy-5β-cholanoic acid, tauro-7α,12β-dihydroxy-5β-cholanoic acid and glyco-7β,12α-dihydroxy-5β-cholanoic acid 7-sulfate is a suitable combination as internal standard compounds for the latter method

Effect of Partial Ileal Bypass on Cholesterol and Bile Acid Metabolism in Rats

In order to clarify the effect of ileal bypass on cholesterol and bile acid metabolism, partial (20 cm) ileal bypass rats were fed a 2% cholesterol supplemented diet for a week after 4 weeks of the operation. The serum and liver cholesterol and phospholipid levels, biliary cholesterol, phospholipid and bile acid secretions, and fecal cholesterol, coprostanol and bile acid excretions were examined. The serum cholesterol level in ileal bypass rats was lower than in normal rats and no hypercholesterolemia was brought about in ileal bypass rats by feeding them the cholesterol diet. The liver cholesterol level increased by feeding the cholesterol diet even in ileal bypass rats but the increase was far less than that in normal rats (22% versus 57%). Biliary bile acid secretion decreased and fecal bile acid excretion increased markedly in ileal bypass rats. Deoxycholic acid increased remarkably in both bile and feces and resulted in an increase in the ratio of the sum of bile acids derived from cholic acid over the sum of bile acids derived from chenodeoxycholic acid (CA/CDCA ratio) in the feces. These results suggest that the absorption of bile acids is impaired, the pool size of bile acids decreases and the hepatic synthesis of bile acids, especially that of cholic acid, increases in ileal bypass rats. As a result, cholesterol feeding to ileal bypass rats produces neither hypercholesterolemia nor a further increase in bile acid synthesis