Carex albata Boott is a weed that invades sown pastures and dominates by seed reproduction. To examine the traits of a C.albata soil seed bank, we collected soil samples from several grasslands prior to the seed dispersal and inveatigated the density of buried seeds by the seedling emergence method. C.albata buried seeds were found in all of the grasslands researched. It became clear that C.albata forms a persistent soil seed bank. The germinative soil seed density of C.albata increased with increase in the coverage above ground level. Particularly, in sown pastures, which have high C.albata coverage, the germinative soil seed density was high ; 78, 580 seeds/m^2. C.albata seeds have no special apparatus for dispersal, and they seem to accumulate predominantly in the soil of C.albata-dominant pastures. On the other hand, in grasslands, where C.albata hardly appeared above ground level, C.albata seeds were found in the soil. Their accumulation may have been caused by animal-assisted dispersal. In sown pastures, bare ground frequently occurs as a result of trampling and treading by grazing animals or by farm vehicles used in grassland management. Thus, C.albata, which forms a persistent soil seed bank over a wide area of a pasture, appears to have the advantages of invasion and domination of sown pastures.

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In order to understand the temporal changes of biomass and botanical composition in grassland ecosystems, and to clarify the relation between these changes and environmental impacts, such as climatic factors and artificial disturbance, a grazing trial was carried out during a 21 year period from 1974 at a sown grassland of the National Grassland Research Institute, located in the central area of Japan, and the data sets of biomass for each mouth(from April to November) of the 21 year period were analyzed. Aboveground biomass in the period from 1974 to 1981 ranged from 180 to 260gDWm^<-2> in a heavy grazing plot and from 200 to 360gDWm^<-2> in a light grazing plot, both with large seasonal variations. In the period from 1982 to 1989, it ranged from 150 to 380gDWm^<-2> in a low nitrogen plot, and from 240 to 360gDWm^<-2> in a high nitrogen plot. In the period from 1990 to 1994, it ranged from 240 to 340gDWm^<-2>. The highest aboveground biomass was recorded in May and June, and the lowest was recorded in November for each of the treatments for each year. The underground biomass tended to decrease from year to year. The amount of aboveground dead material varied greatly with season and year, and tended to have a high positive correlation with the aboveground biomass. The botanical composition varied greatly with season and year. The biomass ratio of improved herbage species to invaded native plants gradually decreased with increasing years. This might be due to meteorological factors such as low air-temperature in winter, or dry and hot summers, grassland management including grazing intensity and fertilizer application, and inter-specific competition between native and introduced herbage plants.

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We studied the floristic composition, above-ground biomass and stand species diversity in grasslands under different grazing intensities in the Xilin River basin in Inner Mongolia. People take the sheep from the livestock sheds in the village for grazing in the morning and return to the village in the evening. Therefore, the grasslands near the village were more intensively grazed than the stands away from the village. Lightly grazed stands were basically dominated by Leymus chinensis (Synonym : Aneurolepidium chinense) and Stipa grandis. By contrast, Cleistogenes squarrosa dominated the intensively grazed stands. The biomass varied from 303gm^<-2> in lightly grazed stand to 127.3gm^<-2> in intensively grazed stand. Stand species diversity indices were 3.13-3.64 irrespective of grazing pressure. We evaluated the stand quality under varying pasture conditions using a stand quality index(SQI). The SQIs were 278 for an intensively grazed stand and 667 for a lightly grazed stand, which was located 4km away from the village. Thirteen years of enclosure improved the SQI of the grassland from 420 to 624. The relationship between biomass and v-value, which was derived from values of plant height and coverage, was determined. Using the v-value, it was possible to nondestructively estimate the biomass of a stand.

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The increase of atmospheric carbon dioxide(CO_2) concentration that will occur in the future may affect the value of feed in two ways : directly by influencing plant physiology (independently of plant size) or indirectly through an increase in plant size(dependently on plant size). In this study, we attempted to clarify the important direct(size-independent) effect of CO_2 enrichment on the feeds of perennial ryegrass and red clover by growing them under ambient and elevated CO_2(about 700ppm) concentrations for two years at the Experiment Farms, Hokkaido University. Carbon dioxide enrichment clearly increased dry matter yield(DMY). It also altered to greater or lesser extent the percentage of dry matter and concentrations of minerals(N, P, K) and acid detergent fiber(ADF) in both species at cutting time, with the exception of ADF concentration in perennial ryegrass. However, the relationships of DMY with fresh matter, mineral and ADF yields did not differ between plants grown at the two CO_2 concentrations, except for mineral yields in perennial ryegrass. These results suggest that CO_2 enrichment did not directly affect the percentage of dry matter and ADF concentration in both species, or mineral concentrations in red clover. The mineral yields(concentrations) in perennial ryegrass tended to increase with CO_2 enrichment at any DMY(size-independently). Long-term CO_2 enrichment decreased ryegrass tiller size and caused root accumulation. These morphological changes were thought to increase the proportion of younger leaves and to make mineral absorption easier, which might consequently increase the mineral concentrations.

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This experiment was conducted to investigate the use of n-alkanes for estimating forage intake. Four species of hay(timothy(TY), Italian ryegrass(IR), Chinese wild rye(CR) and alfalfa(AL) with different n-alkane contents were offered. Eight sheep were assigned to four groups in a replicated(n=2)4×4 Latin square design. Sheep were dosed twice daily with paper pellet containing a daily 128mg of Octacosane(C28) and 120mg of Dotriacontane(C32). During the last 7 days of the 14 days-dosing period, the amount of herbage intake and collected feces were weighed. Herbage intake was estimated using n-alkane contents in herbage and in feces. Actual DM intake and herbage DM digestibility were different among species. The content of Hentriacontane(C31) in TY was less then 50mg/kgDM and in AL was over 400mg/kgDM. There was no relationship between n-alkane chain length and fecal recoveries. And the fecal recoveries of C31 and C32 were not different among species. The ratio of recovery in feces of C31 and C32 was within 1.10 in the species. The most accurate estimation of intake was obtained using C31 and C32 concentration. These results suggest that accurate estimation of herbage intake by alkane method is possible from the simultaneous use of longer chain and high concentration in herbage.

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The objective of this study was to evaluate the suitability of Meadow fescue(Mf) pasture for intensive grazing of high-producing dairy cows. Trials were conducted to compare milk productivities of cows grazed on Mf pasture and on perennial ryegrass(Pf) pasture over a five-year period. Experimental cows were spring-calved and were grazed from May to October for about 180 days. There were no significant differences between the effects of Mf pasture and Pr pasture on milk production, quality of milk, body condition score, concentrations of blood constituents and total digestible nutrient(TDN) supply from grazing. Since the 4% fat corrected milk(FCM) production from cows grazed on both pastures reached 8, 500kg/ha, the milk productivity of the Mf pasture was thought to be the same as that of the Pr pasture. On the other hand, over 60% of the TDN demand of the cows was supplied by self-supplying feed during the grazing season except for the first year, and this was considered to be due to the effect of intensive grazing.

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Land-use system(grazing or harvesting) and its relation to milk yield in dairy farms were investigated in a grassland farming area in Hokkaido. Data of land area, land utilization system, number of cattle, amount of feed purchased and milk production of forty-two farms in eastern part of Hokkaido were analyzed. Total land area of farm positively related to harvesting sward area, but there was no relation between total land area and grazing pasture area or proportion of pasture area. Number of cows of farm did not relate to total land area. Amount of purchased feed offered per cow and self-sufficiency rate of feed did not related to total land area for production of self-supplying feed(grazing and harvesting). Amount of purchased feed offered per cow increased as number of cows per farm increased and, hence, self-sufficiency rate decreased as number of cows increased. Number of cows per unit land area did not relate to amount of purchased feed offered and self-sufficiency rate. Amount of purchased feed offered per cow positively related to milk yield per cow. These results suggested that number of cows and amount of feed purchased did not related to land area of farm, and this means that the land-use system was not considered to be effective for milk production in the grassland farming area.

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Land-use system of thirty-two dairy farms in eastern part of Hokkaido were classified, based on land area, land utilization, number of cattle, herd structure and amount of feed purchased. The relationships between these classifications and milk production were discussed. In the view of land area and the utilization, the dairy farms were classified into [Small area & Pasture dependent], [Small area & Meadow dependent], [Large area & Separate use]and[Large area & Dual use]type. Also, in the view of number of cattle and herd structure, the dairy farms were classified into[Small], [Large], [Large milking]and[Small milking]herd type. The farms of pasture dependent and dual use type, which relative highly depended on grazing, offered higher or similar amount of purchased feed, compared with the farms of meadow dependent type, although milk yield per cow tended to be lower than that of meadow dependent farms. Milk output per unit land area was lower in the grazing dependent farms than in the meadow dependent farms. These results suggested that the dairy farms which highly dependent on grazing have some problems in the utilization of self supplied roughage, in particular grazing management.

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This study was designed to determine the effect of maceration on in sacco degradability and digestibility of low-moisture silage. First and second cutting alfalfa(Medicago sativa L.) or second cutting timothy(Phleum pratense L.) were prepared. Two treatments were ; 1)maceration, processed with a large-scale forage mat maker prior to wilting to approximately 50% DM content(FM treatment), and 2)conventional conditioning, tedded and wilted to the same DM content as that in the FM treatment(CC treatment). These silages were chopped into 20mm length for each experiment. In sacco DM degradability was similar for both FM- and CC-treated silage, but CP degradability of FM-treated alfalfa silage was higher than that of CC-treated one. There were no differences between FM- and CC-treated silage in DM, OM, ADF and NDF digestibility, and TDN contents of alfalfa and timothy. In first cutting alfalfa silage, there were no significant differences between FM- and CC-treated silage in energy digestibility and metabolizability. These results suggested that maceration increased the degradable fraction of CP in the alfalfa stem. However, in chopped silage, maceration has no effects on digestibility and metabolizability of energy.

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