The mechanisms underlying the changes in competitive outcome between the two cultivars of tall fescue, Hokuryo and Kentucky 31, were examined by a factorial experiment involving a combination of soil fertility, plant density and defoliation treatment under pot conditions. In monocultures, Hokuryo was more productive than Kentucky 31, but defoliation treatment negated the differences in productivity between the two cultivars. The competition study showed that defoliation and soil fertility, and their interaction had significant effects on the relative performance of the two cultivars in mixtures. Although Hokuryo was more competitive than Kentucky 31 without defoliation, the competitive superiority of Hokuryo over Kentucky 31 was lost with defoliation treatment. The adverse effects of defoliation on the competitive performance of Hokuryo was enhanced under conditions of a low soil nutrient level and high plant density. The results suggest that (1) the competitive outcome between Hokuryo and Kentucky 31 is determined by the relative balance between potential productivity and regrowth ability after defoliation, and (2) the relative importance of defoliation on competitive outcome between the two cultivars increases with an increase in nutrient stress and intensity of competition.

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In the current study, the spatial pattern of a grazing cattle herd was statistically analyzed including : (1) the spatial pattern formed among the individuals in a herd, (2) the degree of dispersion of the individuals over the whole area of the pasture and (3) the relationship between the spatial pattern and the dispersion. The experiments were carried out on a pasture with an area of 105m×50m where eight young Holstein cows were grazed. Results are as follows : (1) the spatial pattern among the individuals in the herd changed between random, regular and aggregated patterns from time to time. (2) The dispersion of the individuals over the whole area of the pasture was highly aggregated, that is, the individuals in the herd formed a close crowd although the area occupied by the herd fluctuated as the animals wandered about in the pasture. (3) No clear relationship was found between the spatial pattern and the dispersion.

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In a Japanese Black Cattle rearing system utilizing a bahiagrass pasture in coastal Miyazaki, various factors considered to affect animal production were measured for 3 years, and their variations with the year, season and progressive grazing were examined. The air temperatures increased from May to July / August, and decreased from August/September to October. The solar radiation and rainfall showed different seasonal variations with the years. The intake of supplementary feed varied almost similarly to the level of supplementary feeding. The sward height and herbage mass tended to increase from May to July/August and decrease thereafter, except for some sudden drops by the mowings. As a paddock was progressively grazed, the sward height and herbage mass sometimes increased, though they mostly decreased. The sward bulk density showed different seasonal variations with the years. The dry matter digestibility of bahiagrass leaves and pasture decreased from May to August and leveled off thereafter. The animal liveweight, except for some drops with changes in herd composition, always increased. The herbage allowance, except for the first year, showed similar seasonal variations to the herbage mass. The percentage grazing time showed different seasonal variations with the years. The biting rate and the number of bites tended to decrease from May to July / August and increase thereafter. The dry matter digestibility of hand-plucked herbage showed similar seasonal variations to the pasture digestibility. For clarifying the mechanisms of such factor variabilities and characterizing the system, an analysis of the relationships between the factors was considered to be important.

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This study, in a Japanese Black Cattle rearing system utilizing a bahiagrass pasture in coastal Miyazaki, investigated the relationships between various factors considered to affect animal production. The dry matter intake of supplementary feed increased as the level of supplementary feeding was raised. The sward height, sward bulk density and herbage allowance were positively and most highly correlated with the herbage mass. The dry matter digestibility (DMD) of pasture linearly increased with the increasing percentage of Italian ryegrass in the yield, and exponentially decreased with the increasing day number from 1 May and herbage mass. The percentage grazing time exponentially decreased with the increase in the digestible dry matter intake of supplementary feed, and linearly decreased with the increase in the mean daily air temperature above 25.5℃. On the biting rate, the sward height had a negative threshold effect and the DMD of hand-plucked herbage a positive linear effect. The number of bites at pasture showed positive correlations with the percentage grazing time and the biting rate. The DMD of hand-plucked herbage was higher than the DMD of pasture (D_p) when D_p < 0.608 g DM (g DM)^<-1>, and equaled D_p when D_p ≧ 0.608 g DM (g DM)^<-1>. With a correlation matrix and mathematical models, some mechanisms of the factor variabilities were clarified and several characteristics of the system were highlighted. The models were considered to be incorporable into a model of the whole system in future studies, in search of the information for optimizing the animal production.

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In order to transfer rhizomatous growth habit of T. medium (2n=80) into T. pratense (2n=28), a chromosome-doubled interspecific hybrid was produced by colchicine treatment of hybrid embryos. Pollen fertility of the hybrid, the first and the second backcross progeny of the hybrid to T. pratense, were 1.1%, 0-4.6%, and 2.3-36.8%, respectively. The second backcross progeny produced normal seeds when pollinated with T. pratense. Chromosome number of the third backcross progeny ranged from 2n=32 to 42. Backcross progeny produced rhizomes, which should allow long-term persistence of the stands. Backcross progeny with acceptable levels of fertility produced in this study provides useful material for the development of persistent T. pratense cultivars. Recurrent selection of T. medium for interspecific compatibility would further increase fertility of chromosome-doubled hybrids and backcross progeny.

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To obtain alfalfa cell lines with high phenylalanine ammonia-lyase (PAL) activity in response to heat-released cell wall components (elicitor) of an alfalfa pathogen (Verticillium albo-atrum), in vitro selection was performed. The selection using a replica plating methods was carried out on 65 cell lines derived from suspension cultures treated and/or non-treated with N-metyl-N'-nitro-N-nitrosoguanidine (MNNG) of the susceptible genotype of cv. Vertus. Three stable high PAL cell lines in response to elicitor (two cell lines recovered from MNNG treatment, one from non-MNNG treatment) were isolated. All these cell lines showed higher PAL activities, lignin depositions and phytoalexin accumulations than the parental cell line after treatment with active V. albo-atrum conidia. These results indicate that PAL may be a good marker for in vitro selection for Alfalfa Verticillium wilt.

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Seasonal fluctuation of herbage production and animal production were investigated on a pasture (total area, 2.0 ha) consisting of a bermudagrass swards (0.42 ha), temperate grass swards (total area, 0.98 ha) and the white clover swards (0.60 ha). The experimental pasture was divided into 17〜20 paddocks, and grazed rotationally by 12 steers from April until October in 1991 and 1992. In summer (late July〜mid-September), the steers were divided into two herds (Herd and Herd II) that each had six steers. Herd II was grazed on the bermudagrass swards and a part of the white colover swardthe (0.18 ha), Herd I was grazed on the remaining part of the experimental pasture. While productivity of the temperate grass swards declined in summer, the bermudagrass sward supplied sufficient forage to make up for the summer depression of temperate species. As a result, daily liveweight gains of both Herd I and Herd II were high not only in summer (0.75〜0.84 kg) but also in the whole grazing season (0.59〜0.63 kg) in the two years. These results indicated the advantages of combining the bermudagrass swards with the temperate grass swards.

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Using breeding cows of Japanese black cattle, a palatability trial was carried out to find the varietal differences of palatability trial among sorghum silages, comparing with corn ("P 3352") silage as a control. Silage was made of six varieties of sorghum ; three sorgo-type ("Sugar graze", "FS 902" and "Tentaka"), one dual purpose-type ("Suzuho") and two grain-type ("BR 48" and "F_6-3 A-5"). Six adult cows of Japanese Black Cattle were used as a panel. Palatability of each silage was evaluated by daily dry matter intake under cafeteria feeding method, omitting repeatedly the most palatable silage day after day. All six cows in the panel significantly agreed (p<0.01) in their palatabilities for each silage. In general, palatability of breeding cows of Japanese Black Cattle for seven used silages decreased in the following order : "P 3352" (corn) > "F_6-3 A-5" ≒ "Suzuho" ≒ "BR 48" > "Sugar graze" > "FS 902" ≧ "Tentaka". Palatabilities of grain and dual purpose-type were significantly superior (p<0.01) to those of sorgo-type. However, there was no variety of sorghum superior to corn in the palatability.

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Using breeding cows of Japanese black cattle, palatability trials were carried out to find the varietal differences of palatability among sorghum silages, and corn ("P 3352") silage as a control. Silage was made of ten varieties of sorghum ; three grain-type ("F_6-3A-5", "BR 48" and "GS 401"), one dual purpose-type ("Suzuho"), five sorgo-type ("FS 4", "Sugar graze", "Kazetachi", "Hoki morokoshi" and "Tentaka") and one sudan grass ("HS 33"). They were divided into two groups. One, palatable group, consisted of "P 3352", "F_6-3 A-5", "BR 48", "GS 401", "Suzuho" and "Sugar graze". The other, poor-palatable group, consisted of "FS 4", "Kazetachi", "Hoki morokoshi", "Tentaka", "HS 33" and "Sugar graze". Six adult cows of Japanese black cattle were used as a panel. Palatability of each silage was evaluated according to the dry matter intake by six cows which were allowed to eat any of two varieties with all possible pairs during a day. There were significant differences in palatability among the varieties of sorghum. In general, the palatability of cows to six kinds of silages in the palatable group decreased in the following order : "P 3352 (corn)"^A > "F_6-3A-5 "^B ≧ "Suzuho"^B > "BR 48"^C ≧ "GS 401"^<C,D> ≧ "Sugar graze"^D, and in the poor-palatable group, "HS 33"^A ≧ "FS 4"^<A,B> ≧ "Sugar graze"^B > "Kazetachi"^C > "Hoki morokoshi"D ≧ "Tentaka"^D (^<A,B,C,D> : different letters show the significant differeces among the varieties at p<0.05).

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Chemical compositions and in vitro dry matter digestibilities (IVDMD) in straws were compared among twenty four varieties and strains of rice (Oryza sativa L.), consisting of fourteen japonica type rice and ten indica type rice in experiment 1. and each proportion of straw fractions ; leaf blade, leaf sheath and stem, and chemical composition and IVDMD of each fraction were examined on rice straws of four varieties ; Akihikari, Reimei, Habataki and Raikei in experiment 2. The mean culm length was shorter in indica types than japonica types, and acid detergent lignin (ADL) content tended to be higher in japonica types than indica types. There was no apparent difference in the other chemical composition between japonica types and indica types. IVDMD ranged from 37.7% to 52.2%. The mean IVDMD was higher in indica types than japonica types and the difference between two types was about 7%. Crude protein (CP) content had a positive correlation, and culm length, organic matter (OM), acid detergent fiber (ADF) and ADL contents had negative correlations with IVDMD. There was no apparent difference in the proportions of straw fraction. But, the IVDMD of the fraction of Habataki and Raikei were higher than Akichikara and Reimei. These results indicate that differences in IVDMD are mainly dependent on IVDMD of the straw fraction. There were singificant correlations between IVDMD and culm length, OM, CP, ADF and ADL contents of rice straws.

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Rice (Oryza sativa L.) straws of four varieties and strains (Akichikara, Koshihikari, Hokuriku 147 and Hokuriku 148) were compared on nutritive value. In order to investigate the digestibility and energy balance of rice straw, four Japanese native goats were fed rice straw at maintenance TDN level by using a Latin square design. Rice straws were adjusted with soybean meal so that crude protein content was 12%. Culm length (cm) and straw yield (DM kg/a) in Koshihikari were higher than those in other varieties. There was no apparent difference among the varieties and strains in chemical compositions. However, acid detergent lignin content tended to be lower in Hokuriku 147. Digestibility of dry matter, organic matter, ether extract, organic cell wall, acid detergent fiber, cellulose and energy of Hokuriku 147 were higher than the other varieties. Total digestible nutrient, digestible energy and metabolic energy in Hokuriku 147 were higher than those in Akichikara and Koshihikari. Energy excretion in feces and urine was lower in Hokuriku 147 than those in Akichikara and Koshihikari. It is suggested that differences in nutritive value of rice straw are mainly dependent on digestibility of fiber ingredient and energy excretion in feces and urine.

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This experiment was conducted to clarify the effect of varieties and strains of rice (Oryza sativa L.) on their chemical composition and in vitro dry matter digestibility (IVDMD) of sodium hydroxide and ammonia treated straw. Straws of twenty four rice varieties and strains from fourteen japonica types, ten indica types were treated with sodium hydroxide and ammonia, respectively. The chemical composition and IVDMD of those rice straws were examined. The organic cell wall (OCW), acid detergent lignin (ADL) and silica contents of rice straws were decreased by sodium hydroxide treatment. The crude protein content was increased and OCW and ADL contents of rice straws were decreased by ammonia treatment. The IVDMD of rice straw was increased by sodium hydroxide and ammonia treatment, respectively. Sodium hydroxide treament was more effective than ammonia treatment. Varieties and strains which were originally low in IVDMD before treatment tended to increase their IVDMD by these alkaline treatments more than those with high IVDMD by nature.

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As a part of the study on the adaptability of timothy cultivars to environmental conditions and breeding of high quality timothy, effects of nitrogen stress on the growth and in vitro dry matter digestibility (DMD) were examined using 5 cultivars. Four clones of each of the cultivar were transplanted in a 1/5,000 a Wagner pot filled previously with a gleyic ordinary andsols, and cultivated in a green house for 50 days. At transplanting, each pot received 0g-6g ammonium sulfate(N 0-N 6), 2g superphosphate of lime and 0.4g potassium sulfate. Among the cultivars, nitrogen stress by GREENWOOD (S_<NC>) for dry weight of leaf blade, stem and under ground part decreased due to nitrogen (N) application, increased due to surplus N application. S_<NC> for dry weight of stem and under groundpart would exhibit a relatively high resistance to no N application, while that of dry weight of leaf blade was low among the cultivars tested. Varietal variation and interaction between N application level and cultivar in S_<NC> for dry weight of leaf blade, stem and under ground part were not significant. Varietal variation in S_<NC> for dry weight showed slight differences, which might be resulted from breeding at the same station. Each cultivar showed the lowest foliage DMD at NO, which increased due to N application. Interaction between N application level and cultivar for foliage DMD were not highly significant.

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Since the ancient times, there has been some aridgrassy plains in the world where grazing of livestock developed. In Japan however, there was no such plains due to its geographical position as humid region despite of the introduction of horses around the third century A, D, from the Korea Peninsula, Initially, bog reeds (Phramites communis), a tall native grass from fertill marsh area around the ex-Kawachi Lake was fed to horse. Then,sixteen pastures were put in the province of Shinano, three quarters of which were also swamp of ex-lakes and flood plains and only three pastures were in a dry area situated at the foot of the volcano, Mt. Asama, and dominated by two tall native grasses, eulalia (Miscanthus sinensis) and needle grass (Imperata cylindrica). After then the tall native grass lands had been used for grazing horses. In 1916, a legislation was made to allow grazing in national forests for the purpose of improvement and breeding of military hores. At the same time, a guidance policy was established based on the eveluation that described the tall native grasses from the food of volcanoes as the best fooder.

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