Effects of microbes gathered from different portions of the rumen contents, and the presence of nitrogen (N) sources and reducing agents on the digestibility of forage using in vitro incubation with rumen microbes were studied. In vitro method using washed cell suspensions of rumen microbes (WCS) isolated under anaerobic conditions was also compared. The outline of results is as follows. 1) Addition of N source (urea, 100mg/l as N) to the medium for in vitro incubation was needed for the sufficient digestion of Italian ryegrass hay, but excessive supply of N (over 500mg/l) inhibited fermentation. Addition of amino acids and peptide sources (Trypticase) showed little improvement of digestion, and is not considered to be essential. 2) Supplementing reducing agents seems necessary for sufficient fiber digestion. 3) Mixtures of ruminal liquid and solid portions (LS fluid) included higher numbers of bacteria, and showed higher in vitro digestibility of fiber in Italian ryegrass hay than ruminal liquid portion only. 4) When WCS was used as inoculum, the bacteria numbers and in vitro dry matter digestibility of Italian ryegrass hay remained at a similar level as the LS fluid, suggestion that the incubation with WCS may be a beneficial way to analyze relationships among substrate, microbes and digestion in the rumen.

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A field experiment was conducted to evaluate the effects of clipping intervals on seasonal variations of dry matter production, nitrogen content and in vitro dry matter digestibility, and regrowth system of tall type two grass species of tropical forage, Gatton Panic (Panicum maximum var. maximum JACQ. CV. GATTON) and Hybrid Pennisetum (Pennisetum purpureum SCHUMACH×Pennisetum typhoides (BURMF.) STAPF). The experiment was made under 4 and 8 weeks clipping intervals during the periods from summer to winter in South-western Islands, sub-tropical Japan. The higher total dry matter yields were obtained from 8 weeks interval comparing to 4 weeks intervals in both species, though there was no significant difference between species. The dry matter yield of Gatton Panic tended to increase with increasing of growth temperature, while that of Hybrid Pennisetum appeared to increase with temperature above 25℃ and also higher precipitation. Nitrogen content and dry matter digestibility of both species declined with increasing of growth temperature and with getting longer clipping interval. The content of total non-structural carbohydrate (TNC) in root and stubble decreased after clipping and tended to turn to increase about two weeks later except for Hybrid Pennisetum in winter, regardless of increasing leaf area and tiller number.

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Three sexual autoploid (2n = 32) plants of guineagrass (Panicum maximum JACQ.) were produced by treating germinating diploid seeds with 0.1% colchicine for 4 hours. Flowering date, fertility and leaf length were similar for diploids and the induced tetraploids. Induced tetraploids had shorter stems, fewer tillers and wider leaves. These true-breeding seed propagated induced tetraploid plants were sexual and provide added breeding opportunities for crossing sexual and apomictic guineagrass types at the tetraploid level.

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Breakdown of dung and volatilization of ammonia were studied under moist and dry conditions in a mixed sward of perennial ryegrass and white clover. Treatments were : control, and applications of 2, 4 and 6 kg fresh dung 0.1m ^<-2>. Dung disappearance rate increased with increasing initial dung weight. The highest rates of ammonia volatilization were recorded 10-20 days after dung deposition and volatilization gradually decreased to negligible levels after 40 days. Percentage loss increased with increasing application rate of dung, ranging from 2.8 to 8.1% and 3.4 to 7.4% under moist and dry conditions, respectively. Little difference in total volatilization loss was observed between moist and dry conditions. Dung does not exhibit the same dramatic volatilization of ammonia frequently observed from urine patches.

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Nitrogen loss by denitrification from cattle dung was studied under moist and dry conditions in a mixed sward of perennial ryegrass and white clover. Treatments were : a control and application of 2, 4 and 6kg fresh dung 0.1m ^<-2> (40cm×25cm). Significant positive correlations were observed between surface soil nitrate contents and the daily rates of denitrification (r = 0.766, P<0.001 in moist conditions ; and r = 0.717, P<0.001 in dry conditions). Also, surface soil water content provided the significant, positive correlations with daily rates of denitrification (r = 0.477, P<0.01 in moist conditions ; and r = 0.509, P<0.01 in dry conditions). Percentage loss of dung nitrogen by denitrification increased with increasing dung application rates, ranging from 0.81 to 4.02% and 0.28 to 0.75% under moist and dry conditions, respectively. The losses of nitrogen under moist conditions showed 3-5 times higher values than those under dry conditions. Above results suggested that denitrification normally appears not to be a major pathway for nitrogen losses from cattle dung voided on pasture, compared to the nitrogen loss by ammonia volatilization (previous paper).

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Orchardgrass is one of the major forage grass species in northern Japan, but ruminant livestock grazing on orchardgrass pastures sometimes suffer from grass tetany. If sufficient differences in mineral concentrations exist among orchardgrass cultivars, farmers can reduce the metabolic disorder potential by selecting better cultivars. This study was to investigate the differences in mineral concentrations among orchardgrass cultivars under sheep grazing conditions. There were significant differences among orchardgrass cultivars for N, P, Ca, Mg, SiO _2 and the ratio of K/(Ca+Mg). The concentrations of Ca and Mg for cv. Okamidori were significantly higher than those of other cultivars. The differences between cv. Okamidori and the lowest cv. Akimidori were 0.043 and 0.045 units in Ca and Mg, respectively. The differences resulted in the lower K/(Ca+Mg) ratio of Okamidori (2.53), compared with cv. Akimidori (2.87). Okamidori is considered to be useful for a breeding material reducing the grass tetany potential.

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To investigate seasonal changes in relative concentrations of cellular constituents, four orchardgrasses, a tall fescue, and a perennial ryegrass cultivars were sampled thirteen times during growing seasons over three years. These samples were partitioned into three cellular constituents ; cellular content (CC), high-digestible cell wall (CWa), and low-digestible cell wall (CWb). Digestible organic matter (DOM) was then estimated from organic matter percentages of these constituents. In all entries, percentages of CC were high in spring and in fall, and low in mid summer. Conversely, those of CWb were high in mid summer, and low in spring and in fall. All equations in seasonal change of CC and CWb could be expressed quadratically. Though quadratic equations were fitted best in CWa of ryegrass and tall fescue, those of orchardgrass were linear or near linear, even if they fitted to quadratic equations. Among the entries with mean percentage of cellular constituents over three years, Yatugane ryegrass indicated the highest values in CC, organic CC (OCC), CWa, organic CWa (Oa), ash, and digestible organic matter (DOM), and showed the lowest values in CWb and organic CWb (Ob). The values found in Hokuryo fescue were totally inverse to those of Yatugane ryegrass. Among four orchardgrass cultivars, Okamidori showed the highest values in the percentages of CC, OCC and DOM, and the lowest in CWb and Ob. There were little difference in these fractions among the other cultivars. There is no significant difference in CWa and in Oa.

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This experiment aimed to develop a new system for supply of manure slurry to the crop field without scattering of unpleasant odors. An instrument having two bomb-shaped iron blocks, which were connected to a rotary plow by arming with iron plates, was made to produce two lateral holes of 15 cm diameter in the underground of 45 cm depth at intervals of 90 cm spacing. This instrument was equipped to a farm tractor with a combination of the rotary plow, seeder and land roller. Thus the tractor could operate systematically plowing, hole digging, seeding and roll-pressing. The slurry was transferred to the crop field through a polyethylene duct hose by pressure and injcctcd to the holes. There could supply the slurry 20 ton/10a at an application. The application of slurry was able to repeat 10 times during the cultivation of corn in this experiment. The control field was fertilized by conventional methods. Moisture, total nitrogen and nitrate nitrogen of soil were measured 5 times during the growing period of corn. There appeared to increase nitrate- nitrogen in the soil of the slurry injected field, especially at 30 cm level of the underground. However at the harvest time the levels of nitrate-nitrogen of fresh corn (dough stage) on the control field and the slurry-injected field were 0.06% and 0.09% in D M basis, respectively. These values were under a secure range of nitrate content concerning to the nitrate poisoning. The yield of corn did not differ in the two fields (control field 1.80 and slurry-injected field 1.92 ton/10 a). Although the hole was damaged by driving corn-harvester and/or following dump trailer, the intensity of hole was consistent enough to supply slurry through the period of corn cultivation. These results indicated that this slurry application system is quite suitable not only to the flat field but also to the field in urbanizing area.

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Eight mixtures of chopped rice straw - 1) Co : rice straw (RS) alone ; 2) Mo 10 : RS+molasses (10% DM) ; 3) Mo 20 : RS+molasses (20% DM) ; 4) Mo 30 : RS+molasses (30% DM) ; 5) Ur : RS+urea (5% DM) ; 6) Bm ; RS+broiler manure (20% DM) ; 7) UrMo : RS+urea (5% DM) +molasses (20% DM) ; and 8) BmMo : RS+broiler manure (20% DM)+molasses (20% DM) - were packed in 20-kg laboratory silos and allowed to ferment. Samples were taken before processing and 15, 30 and 45 days after processing and subjected to analysis. Proximate composition of initial mixtures was generally the same as that of 15-day, 30-day and 45-day mixtures. Crude protein of mixtures with urea or broiler manure (Ur, Bm, UrMo and BmMo) were higher than those without (p<0.01). No molds were seen in all treatment groups in all mixtures (15-day, 30-day and 45 day). pH decreased from 1 day to 15-day in all mixtures. All treated mixtures, except Ur and UrMo had lower pH than control (p<0.01). Treated mixtures had higher lactic acid than control (p<0.01). UrMo had the highest lactic acid values (p<0.01). Silage quality as expressed in Fileg point increased in all mixtures, except control, from 15-day. to 45-day. UrMo and BmMo had consistently higher fry organic matter digestibility and total digestible nutrients (TDN) than control (p<0.01). Nylon bag-in vivo dry matter digestibility of all mixtures, except Bm, was higher than that of control (p<0.01). Rice straw processed with urea and molasses or broiler manure and molasses showed the highest nutritive value in terms of CP, fiber content, digestibility, TDN and silage quality.

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A pot experiment, in a rain shelter covered with transparent polyvinyl chloride sheet, was conducted to evaluate the effects of flooding and drought conditions on morphological and agronomical characteristics of phasey bean (Macroptilium lathyroides L.URB.) during its vegetative and reproductive stages. The experiment was carried out at the Nihon University Farm located in Fujisawa from June to October 1990. When the plants were still in vegetative stage the treatments of flooding and drought were initiated. Same treatments were commenced at the flowering stage and also at the ripening stage. In the flooding treatment the pots were flooded by watering up to 5 cm from soil surface. On the other hand, the drought treatment was not irrigated. The flooding led to develop grater elongation of plant length and higher DM yield with more suitable growth parameters, and more numerous nodule number than those in normal and drought conditions. The results indicated that, when the flooding was initiated at the vegetative stage, the dry matter yield appeared to be largest. In the same way, the detrimental effect of drought on the plant was observed to be less when it was initiated at the vegetative stage.

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Data of coverage and frequency were analysed with the principal component analysis method in order to classify the pasture types and identity the succession of the pasture types. The vegetation survey was carried out with the quadrat method in 18 pastures of the Tohoku University Farm which was located in northern main land of Japan. The following results were obtained ; 1. The dominant species in most pastures were orchardgrass and /or white clover. However, redtop (Agrostis alba) and weeds species occurred abundantly in some pastures and these indicated characteristics of the pasture condition. 2. It was found that species of Anthoxanthum odoratum, Artemisia princeps, Petasites japonicus, Equisetum arvense, Polygonum cuspidatum, Rumex acetocella, Hydrocotyle ramiflora and Miscanthus sinensis had a high positive correlation coefficient with each other and had a high negative correlation coefficient with perennial ryegrass. This suggests that these species grow together in the same site while perennial ryegrass grow in the other site separately from these species. These species seem to appear in the degenerated pastures and are designated as the anthoxanthum group. This group and redtop had a high factor loading of the first principal component of coverage, and were worth noticing in the classification of the pasture types. 3. Based upon this information and dominant species, the surveyed pastures were classified into 4 types. The type A consists mostly of orchardgrass and/or white clover and a few weed species. The type B contains much redtop and a few weeds. The type C contains an amount of the anthoxantum group and much orchardgrass and with clover. The type D consists mostly of the anthoxantum group with a smaller amount of orchardgrass and white clover. Number of pastures belonged to the pasture type A, B, C and D were 7, 5, 3 and 3, respectively. 4. It is considered that the type A is the initial stage of development with basic species structure and in excellent condition ; the type B and C are pastures of middle-aged and show signs of deterioration ; and the type D is and old pasture in deteriorated condition.

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Lolium perenne L. has been previously reported as showing allelopathic characteristics. The objective of this study was to determine the types and amounts of phenolic inhibitors contained in free state in tissues of Lolium perenne shoots by the use of chemical analyses and bioassays. The results obtained are summarized as follows : 1. Aqueous extracts from Lolium shoots caused reduction in germination and seedling growth of Trifolium repens in bioassay ; July-extract causing the greatest inhibition and September-extract the least. The acidic and neutral fraction from July-extract was most inhibitory, while the basic fraction had no effect. 2. Through the use of chromatographic separation, twelve phenolic compounds such as chlorogenic acid, p-coumaric acid, caffeic acid several other compounds were identified in the acidic and neutral fraction. Among them chlorogenic acid was predominant (4.4 mg/g shoot DM) and all the other compounds were found at very low concentrations. 3. Chlorogenic acid apparently inhibited germination and seedling growth of Trifolium repens. However its degradation products, caffeic acid and quinic acid were higher in inhibitory effect on those of Trifolium compared with chlorogenic acid. 4. In general, it was found that the extracts containing the higher amount of chlorogenic acid tended to exhibit the greater inhibition to the Trifolium germination and growth (Fig.4). 5. It is suggested from these results that the allelopathic activity in the leachate from Lolium perenne is partly due to chlorogenic acid.

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