Conversion of paddy fields into pastures for use by grazing cattle is an important option for animal production and conservation of agricultural land in Japan. However, trampling by animals on the high-moisture soil in the converted pastures may lead to degradation of sown forage species and generation of weeds. This study investigated vegetation characteristics and soil moisture content in three paddy-field pastures varying in grazing history, Pastures T (first to second years of grazing), N3 (third year) and N8 (eighth year), and also in a pasture in an upland field as a control (Pasture C, second year). Botanical composition was determined using the dry-weight-rank method. The soil moisture content was highest in Pasture N3, followed by Pastures T, N8 and C. The number of paddy-field weed species occurring in Pastures T, N3, N8 and C was 10, 16, 8 and 1, respectively. The dominance by paddy-field weeds was higher in Pasture N3 than in Pastures T and N8. The proportion of total weeds (paddy-field+non-paddy-field type) in plant biomass was lower in Pasture T than in Pastures N3 and N8. The proportion of paddy-field weeds in the total weeds decreased as the grazing year increased.

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Fecal excretion of undigested rice grain was investigated in cattle fed grains in various conditions [different sizes, threshed vs. non-threshed (as panicle), intact vs. mechanically treated]. In Trial 1, cattle were fed rice whole crop silage of a large-grain or a middle-grain variety at a maintenance level. The proportion of undigested grain excretion to the intake was similar in the two varieties with values below 5%. In Trial 2, cattle were fed grass hay added with differently treated grains collected from rice whole crop silage. The excretion of undigested grain was lower in non-threshed grains (as panicle) than in threshed grains, in mechanically treated grains than in non-treated grains, and with a lower feeding level of hay. In Trial 3, cattle were fed corn silage or grass hay added with a mixture of air-dried rice grains of large-type (average weight=0.045g) and long-type (average weight=0.026g) varieties. The excretion of undigested grain was lower in the large grain (24%) than in the long grain (44%). The results show that digestion of rice grain in cattle is affected by threshing in silage feeding and by grain size in grain feeding.

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Effect of the main roughage on palatability of total mixed rations (TMR) with green tea waste silage (TWS) was examined for lactating dairy cows. In experiment 1, the main roughage in TMR (basal diet) was timothy hay, and the TWS addition rate was 1.25, 2.5, 5, 10 or 20% of TMR on a dry matter basis. In experiment 2, the main roughage in TMR (basal diet) was corn silage, and the TWS proportion was 2.5, 5, 10 or 20% of TMR on a dry matter basis. Four lactating Holstein cows were used for each experiment, and feed intake and preference index were measured. In experiment 1, the feed intake of test diets containing TWS of 1.25, 2.5 and 5% was almost similarto that of the basal diet. The lower discrimination threshold (LDT) of TWS was estimated at 8.1%. On the other hand, in experiment 2, the feed intake of test diets containing TWS of 2.5, 5 and 10% was almost similar to that of the basal diet, and LDT of TWS was estimated at 14.7%. The results show that the upper limit of TWS mixing rate could be 8 and 15% in TMR with timothy hay and corn silage as a main roughage, respectively.

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The objective of this study was to select hybrid ryegrass cultivars with high yield potential, similar to Italian ryegrass (Lolium multiflorum), and with high snow endurance, similar to perennial ryegrass (Lolium perenne), that could be cultivated in regions with cold and heavy snow climates, such as the Tohoku region. Thirty-seven cultivars introduced from abroad were evaluated and compared with six cultivars of related species. One group with relatively large plant size, high snow endurance and good regrowth vigor after summer was extracted by principal component analysis and named group I. The cultivar "Bison" had large culm length and better snow endurance than the other cultivars in group I. However, its snow endurance was inferior to that of the perennial ryegrass cultivars. Snow endurance and size factors such as plant length at the early stage and culm length were negatively correlated. "Bison" had a comparatively small plant length at the early stage. This may be related to its high snow endurance. Through selections with plant length at the early stage and yield after winter as criteria, it is possible to breed a new hybrid ryegrass cultivar with high snow endurance and high yield potential.

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The optimal nitrogen fertilizer rate for perennial ryegrass (Lolium perenne L., cv. Pokoro) meadows cut three times a year in Tenpoku Region, Hokkaido, was determined in a field experiment applying five nitrogen rates (90, 160, 180, 210 and 240kg/ha/year). Herbage DM yield increased as the nitrogen rate increased, with a non-significant difference between the two highest rates. Nitrogen use efficiency was higher at higher nitrogen rates, but the increase in DM yield per unit nitrogen applied peaked at 160-210kg/ha. With the increasing nitrogen rates, in vitro dry-matter digestibility and water-soluble carbohydrate content of herbage decreased, while fiber and crude protein contents increased. The results show that the annual nitrogen rate of 210kg/ha is most suitable for cutting use of perennial ryegrass meadows in the region.

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The Komatsuna germination test is widely used to evaluate compost maturity, but objective comparisons are difficult because the procedures for this test are not uniform. We therefore investigated the conditions for the reproducible procedures used in the Komatsuna germination test, such as volume of liquid, seeding density, temperature and period of culture, and time and germination characteristics for observation. The standard deviation in measured values was small when the volume of liquid submerged the entire seed. Strong suppression of root length by the growth inhibitors in compost was observed along with that of germination rate and root hair emergence. A change in seeding density or culture temperature resulted in a different response to inhibitors. From the above findings, the reproducible conditions for the Komatsuna germination test are suggested to be as follows. Seeding density: 50 grains in a 90-mm diameter petri dish, culture condition: 20℃ for 5 days, volume of liquid: 11ml for 1.6-mm diameter seeds, observations: germination rate on the second day, and length of root and root hair emergence on the fifth day. Moreover, it appears that the most preferable measurement of root length is performed using digital photos of Komatsuna seedlings collected from all parts of the petri dish.

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Bracken infestation is a serious problem for pasture management. Asulam is commonly used to control bracken plants. Recently, rooting by wild boars has been observed in pastures where asulam had been applied for bracken removal. We conducted field experiments to examine whether the use of asulam encouraged rooting by wild boars. We also sought to determine whether boars root the bracken rhizomes and whether the reserve carbohydrate contents of bracken rhizome (glucose equivalent) induced the boars' rooting activity. In July 2003, treatment plots dressed with an asulam solution and non-treated control plots were established in a pasture dominated by bracken. Two months after dressing, we counted rooting places in each plot. The proportion of rooting was significantly greater in the asulam-dressed plots than in the non-dressed plots. Wild boars rooted the bracken rhizomes, but no difference was found in glucose contents of bracken rhizomes between the asulam-dressed plots and the control plots. In pastures used by wild boars as habitat, methods other than asulam, such as cutting, should be used for controlling bracken plants.

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The differences in sensitivity to growth inhibitors and resistivity to pH and salinity in eight varieties of commercially available Komatsuna were investigated to choose suitable varieties for the germination test. The experiment was performed as in our earlier report. It appeared that suitable varieties for the usual germination test applied for various composts were Mineral, Kaoru and Ajisai, in that order. But Kaoru was not appropriate to observe germination due to its whitish seed integument. It was considered that the suitable varieties for germination test using pH-adjusted compost extract were Ajisai, Mineral and Kaoru, in order. From the above findings Ajisai and Mineral seem to be the best varieties for the germination test.

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