In the rearing and fattening system with two grazing seasons, the rearing period of 12 months was divided into two such periods as wintering and grazing periods. The present study was to clarify the effect of growth rate in wintering period on weight gains in the next grazing period and to improve the performance for rearing stage of calves. Animals used were 3 groups of 38 steers and 3 groups of 46 heifers finished nursing stage at 7.3 months of age on average in the fall of 1985 to 1987 at the Livestock Farm, Faculty of Agriculture, Hokkaido University. In wintering period steers and heifers born in the same year were fed and managed in one group. Feeds given were hay and silage, and formula feed for rearing calves with daily allowance of 1.3kg/head. Grass silage (GS) was given in 1985 and 1986, and corn silage (CS) in 1987. Animals were turned out on pasture in one group in the next spring and then heifers were separated to the other group for breeding in September. Average daily gains for steers in wintering period of each year ranged 0.57 to 0.65 kg and the group given CS showed significantly higher daily gain. Average daily gains in grazing period ranged 0.52 to 0.55 kg and a group with higher daily gain in wintering period tended to result in a higher performace for rearing stage. Thus, it is concluded that daily gain in wintering period should be about 0.65 kg to obtain a satisfactory performance of steers for rearing stage. Daily gains of heifers in wintering and grazing periods were about 8% lower than those of steers, but a higher daily gain in wintering period also gave a tendency to be a higher performance of heifers for rearing stage. The daily gain of 0.50 kg in wintering period would give a satisfactory result for heifers considering live weight at the first breeding.

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In order to assess the effect of mounds constructed by Cansu mole-rat (Myospalax cansus LYON.) on shrub-steppe vegetation, the field survey was carried out in 1989 and 1990 in the hilly grassland of Nanhua Mountain situated in the west of the Loess Plateau. The ordination method was applied to vegetation data using a principal component analysis. Soils were sampled and analyzed. Trigonella ruthenica and Potentilla tanacetifolia which have a stoloniferous growth form, showed a high coverage on a new mound and Thymus mongolicus on both new and old mounds. Artemisia species seem to be intolerant for soil disturbance because of a low coverage on a new mound. The species ordination indicated that the trend represented by axes I and II corresponded to the a type of mounds within the northern slope and different slopes, respectively. Apparently higher accumulation of calcium carbonate was obtained on the western lope, compared with that on the northern slope, where there were many mounds of Cansu mole-rat. With respect to total nitrogen and organic matter, Cansu mole-rats destroyed not only shrub-steppe vegetation but also the soil structure especially at a surface layer. Using a mean size of mounds (1.84m^2), the damaged area was estimated as about 15 percent of total area on the northern slope.

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Two experiments were conducted to examine the effects of acremonium cellulase (AC) and lactic acid bacteria inoculant (LAB) on the fermentation quality and feeding value of guineagrass silages. In Experiment 1, wilted and chopped primary growth herbage was treated with water (control) or AC+LAB and ensiled in 500 1 silos. In Experiment 2, first regrowth herbage was treated with water (control) or AC, AC+LAB before ensiling. The additives improved the fermentation quality of the silages. Compared with control, additives treated silages had lower pH ; higher contents of lactic acid, total acids, residual WSC and Flieg's score ; lower butyric acid and ratio of volatile basic nitrogen to total nitrogen. The second harvest herbage produced marginally better quality silages than its first harvest counterpart. LAB treatment had synergistic effects with AC treatment. The AC and AC+LAB treated silages had lower contents of crude fiber, NDF, ADF, cellulose and hemicellulose but higher contents of crude protein, crude fat and NFE than control silages. In Experiment 1, dry matter, organic matter, crude fat and NFE digestibility coefficients of AC+LAB silages were significantly higher than those of control silages. However, in Experiment 2, digestibility was not significantly improved by AC and AC+LAB treatments compared with the relatively better preserved control silages. The DCP and TDN contents of AC and AC+LAB treated silages were greater than those of the control silages and the differences were more pronounced in the first cut silages.

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It is essential to establish a more rational and stable ensuing method for better economic production of ruminant feed. Application of saccharides as silage additives is a usual practice for making high quality silage. However, the efficiency of production of lactic acid by lactic acid bacteria for the different types of saccharides may differ, which may affect the fermentation quality of silage. Experiments were carried out to obtain fundamental data for making good quality silage. Oats, guineagrass, wilted paddy rice and alfalfa (aftermath) were ensued with or without saccharide additives in 1-L laboratory silos. The additives examined were : 1) pentose (xylose, ribose, arabinose), 2) hexose (galactose, glucose, fructose, mannit), 3) disaccharide (maltose, sucrose), 4) polysaccharide (starch). Composition of organic acid and pH were investigated at 7 and 50 days after ensuing. The quality of each oats silage was high because of high water soluble carbohydrate (WSC) content and low lactic buffering capacity (LBC). While, the fermentation quality of other materials with low WSC, such as alfalfa, were relatively low. With regards to organic acid components, pentose saccharides as silage additive resulted in the production of higher acetic acid than other forms of saccharides. Because, in theory 1 mole of pentose is fermented to 1 mole of lactic and acetic acid by lactic acid bacteria. Starch as silage additive did not influence the fermentation quality of silage. Among the silage additives, hexose saccharides efficiently produced lactic acid, because in theory 1 mole of hexose is fermented to 2 moles of lactic acid by lactic acid bacteria. Thus hexose was considered as the best additive compared to the other forms of saccharides. Silage treated with mannit was significantly low in acetic acid content, because heterofermentative lactic acid bacteria can not ferment mannit. The results showed that in terms of lactic acid production, hexose and disaccharides were more efficient than pentose, so the former are better than the latter as silage additives. As an additive, starch did not influence the fermentation quality of silage.

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The fermentation quality and feeding value of guineagrass (Panicum maximum JACQ var. natsukaze), green panic (P. maximum var. trichoglume EYLES), colored guineagrass (P. coloratum L.) and rhodesgrass (Chioris gayana KUNTH var. katambora), under a silage cutting regime of three harvest per growing season were evaluated. The first and second cuttings were field wilted before ensiling but the third was not wilted due to poor weather conditions. In digestion trails the silages were fed to four wethers. The pH values of all silages were high, ranging from 4.6 to 5.8. The lowest pH values were consistently obtained from silages made from Unwilted herbage of the third cutting. The silages were well preserved as indicated by the low contents of butyric acid and volatile basic nitrogen as a percentage of total nitrogen (VBN/T-N). Most of the silages contained more lactic acid than acetic acid. However, the second and third cuttings of green panic and second cutting of colored guineagrass produced acetate-type silages. With the exception of silage prepared from the first cutting of guineagrass, differences among and within the species in digestibilities of DM and other constituents were small. The mean DCP content was in the ranking order green panic (6.6%)>colored guineagrass (5.9%)=rhodesgrass (5.9%)>guineagrass (5.3%). The mean TDN content was in the increasing order of guineagrass (51.8%), green panic (51.9%), colored guineagrass (52.1%), rhodesgrass (53.3%), with only slight differences among species. Relative to rhodesgrass, which was used as a comparison species, the DCP yields of guineagrass, green panic and colored guineagrass were 142, 130, and 102%, respectively. The respective TDN yields of guineagrass, green panic and colored guineagrass were 146, 106, and 91% of that of rhodesgrass. Guineagrass and green panic showed the considerable potential of DCP and TDN yields and compared favorably with rhodesgrass.

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Under conditions of pure sowing and sowing of a grass-legume mixture consisting of Leymus (=Aneurolepidium) chinensis and Hedysarum mongolicum, studies were carried out on the effects of deep ploughing (30cm) and shallow ploughing (15cm) on a degraded grassland in the Stipa steppe in the Alihe Area located in the high latitude winter cold zone of China. The data from the present experiment suggest that the sowing of a mixture of L. chinensis and H. mongolicum with deep ploughing is most suitable for increasing the photosynthetic efficiency, dry matter production of plants and the production of several nutrient substances in comparison with other experimental treatments such as pure sowing of L. chinensis with deep or shallow ploughing, pure sowing of H. mongolicum with deep or shallow ploughing, sowing of a mixture of L. chinensis and H. mongolicum with shallow ploughing, and degraded Stipa baicalensis-forb grassland (control treatment). Thus a new method of establishment of artificial grasslands in the winter cold zone of China by mixed sowing with deep ploughing was developed.

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The purpose of this study is to examine the morphology of macropores in the root zones of grassland on the weathered granitic soil. The soil was sampled in Houzyou city of Shikoku. The structure of macropores was studied three-dimensionally examining the physical condition of the soil and the morphology of macropores by stereoscopic-radiography. The soil samples were collected from four layers of root zones shallower than 45cm on a 10-year old pasture. The physical condition of each soil layer was sandy loam, dense and solid, and the solid phase rate was 52-58%. The macropores and the effective pores were small, and permeability was low in the surface soil layer. The macropores and the effective pores increased in the sub-surface soil layer and the subsoil layer, and permeability was higher in both. The morphology of the non-capillary pores (pF≦1.5) observed on each soil layer. The first soil layer (0-10cm) consisted of pores formed by grass roots. The second to the third soil layer (10-45cm) consisted of pores formed by roots, and pores of inter-particles and inter-aggregates. The morphology of the capillary pores (pF1.8, pF2.0) is shaped by pores formed by roots in the surface layer. In the subsoil layers they were consisted of pores formed by roots, and pores of inter-particles and inter-aggregates. These results on the pore morphology of the weathered granitic soil showed that the shape of almost all macropores is formed by roots. This is the same as that described for the Andosols (volcanic sandy soil) and Steppe soil (chestnut sandy soil) cases. It was concluded that the macropores of the grassland soil consisted mainly of the tubular pores formed by plant roots.

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Two cultivars of paddy rice, Oryza sativa L., i. e., Mitorazu, a local cultivar used for new year's decoration cord and Hamasari, bred for whole crop forage, were grown in paddy field and the harvested samples were examined in terms of growth characteristics and changes of cell-wall each fractions of the straw during three ripening stages using enzymes. Hamasari surpassed Mitorazu in lodging resistance, and the latter lodged entirely at dough to yellow-ripe stage. Plant heights (cm) were 146.9 in the latter and 118.4 in the former with significant difference at p<0.05. Fine stem characteristics in Mitorazu suggested higher suitability for hay making. Dry matter yields (kg/a) of two cultivars were 100-130, and the ratio of straw to total plant decreased with advancing maturity in both cultivars.Among the nutritive components of the straw in both cultivars, 0CC decreased with advancing maturity, while OCW increased instead. And the differences in OM, 0CC, OCW and Ob between three figures in advancing maturity were statistically at p<0.05 in Mitorazu. Hamasari tended to retain assimilates in the straw until later ripening stage. Oa fraction in OCW was always stable in all ripening periods of both cultivars, but Ob fraction increased remarkably in Mitorazu than in Hamasari. From the above results it was suggested that decrease of feeding value during the ripening process has to be considered in case of breeding leafy cultivars for forage rice.

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An experiment was conducted to study the influence of plant maturity and growing temperature on organic matter components of five temperate grasses under simulated grazing condition. Field plots of orchardgrass, tall fescue, perennial ryegrass, Kentucky bluegrass and prairie grass were cut seven or eight times annually over a four year period, and forage samples were taken to determine the percentage content of organic cellular content (OCC), organic cell wall (OCW), high digestion cell wall organic matter (Oa) and low digestion cell wall organic matter (Ob) as well as digestible organic matter (DOM). Maturity of the harvested samples was expressed in terms of the amount of herbage mass (HM) higher than 5cm above the ground, and the growing temperature (GT) was defined as the mean temperature during the regrowth period. The relation between the percentages of the various components and HM and/or GT was then examined for each species. There were significant positive correlations between HM and the percentage content of OCW and Ob in all the examined species except for tall fescue, and there were significant negative correlations between HM and the percentage content of OCC and DOM in three of the species.High GT caused the percentage content of Oa to decrease, and the percentage content of Ob to increase. A significant negative correlation was observed between GT and the percentage content of DOM in both perennial ryegrass and prairie grass.To estimate the effects of HM and GT on the percentage content of DOM, we performed a multiple regression analysis by using DOM as the dependent variable, and HM and GT as the independent variable. The results indicated that the percentage content of DOM declined at a rate of 0.02-0.026% per 1g dry weight/m^2 increase of HM. In addition, the effects of a 1℃ increase in GT on the percentage content of DOM was large in perennial ryegrass and prairie grass (0.62-0.64% per 1℃) and small in orchardgrass and tall fescue (0.25-0.30% per 1℃).

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Chromosome behavior, method of reproduction, fertility and morphological characteristics were studied in a new guineagrass cultivar, Natsukaze, produced by a sexual × apomictic cross. Natsukaze was tetraploid (2n=32) and showed 0-7 quadrivalents at metaphase I. Natsukaze was found in open-pollinated progenies of the diploid sexual line, GR297 (2n=16), and probably resulted from fertilization of an unreduced egg by a reduced sperm from the pollen of a tetraploid apomictic line. Pollen stainability of Natsukaze was 77% and somewhat lower than the diploid female parent (90%) and about the same as an apomictic line, Ku5954 (80%). Natsukaze was facultatively apomictic with 11% sexuality, somewhat higher than that of the apomictic line, which showed ca 2% sexuality. No off-types appeared in the open-pollinated progenies of Natsukaze. Therefore, sexual embryo sacs appear to not compete as well as apomictic sacs. Natsukaze set less seed under self-pollination than under open-pollination which may be due to self-incompatibility genes inherited from GR297.

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Effect of the ratio of nitrogen application in late autumn (autumn N) and the following early spring (spring N) on the grass growth of the first cut in the next year was compared among orchardgrass swards that were previously managed under different rate of N fertilization after the third cut in early September. Autumn N was applied in early November after the last cut (the forth cut). Spring N was applied in early April of the following year. The first cut was conducted in late May. The sum of the rate of autumn N and spring N was constant. Increasing the ratio of autumn N was beneficial to increase the density of earing tillers and total dry matter yields of the first cut in the sward that received low level of N in early September. On the other hand, more earing tillers of the first cut emerged in the sward that received higher level of N in the early September. Increasing N application rate in the early September reduced the effect of ratio of autumn N and spring N on the density of earing tillers of the first cut. Increasing the ratio of spring N resulted in higher yield of vegetative tillers and total dry matter in the sward that received higher level of N in early September. Improvement of N supplying capacity of soil in autumn by application of manure was effective to increase the density of earing tillers, same as autumn N for the sward receiving low rate of N fertilizer in early September. These results show that sufficient supply of N in autumn is necessary to emerge many earing tillers that constitute a majority in the dry matter yield of the first cut in the following spring. Therefore, enhancement of N supplying capacity of soil in autumn is important. Increasing the distribution ratio of autumn N after the last cut of the year is effective to increase the yield of grass in the following spring when the N fertility of soil in autumn is poor.

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