Electrophoretic patterns of restriction endonuclease digests of mitochondrial DNAs (mtDNAs) isolated from alfalfa (Medicago sativa L. and M. falcata L.) cultivars which are traced to different geographical origins and a cytoplasmic male sterile (CMS) line were examined to investigate how mtDNAs of alfalfa cultivars and CMS line are varied. The restriction fragment patterns of alfalfa mtDNAs varied among cultivars and a CMS line. Cluster analyses of restriction fragment patterns revealed that the mtDNA variations mostly coincided with the evolutional processes of the cultivars and the restriction fragment patterns of the CMS line were different from those of the cultivars. These results indicate that the restriction endonuclease analysis of mtDNA provide useful information on evolutionl relationship among alfalfa cultivars and on identifying its male sterile cytoplasm. Low molecular weight DNAs in undigested mtDNA were found only in 'Rambler' out of ten cultivars used. The electrophoretic pattern of the plasmid-like DNAs found in this study was different from that of the other study previously done.

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As part of a wider study on the persistence of pasture legumes, the development of stolons, taproots and adventitious roots of two tropical pasture legumes was examined in subtropical eastern Australia. Plants of C. pubescens (centro) and D. intortum cv. Greenleaf (desmodium) were established at 40cm spacing, and the development of stolons, taproots and adventitious roots was studied by sequential samplings of quadrats centred on both the plants and the interplant areas. Samples were taken throughout the first growing season (December to May) and after the end of the winter (September). Centro had more rooted points per unit area (1,300-2,100m^<-2>) than desmodium (600-1,200m^<-2>), mainly because it had a greater total length of stolon per unit area (c. 300mm^<-2>) than desmodium (c. 90mm^<-2>). However, desmodium stolons were thicker and heavier. Most adventitious roots on both species were small, and neither species had any thick adventitious roots (>4mm diameter) although desmodium had more roots of 1-4mm diameter. Desmodium had a slightly greater weight of roots in the surface 5cm of soil (72gm^<-2>) than centro (62gm^<-2>) at the end of the growing season. Both species rapidly developed an extensive network of stolons and adventitious roots in the year of establishment. However, the ecological and long term significance of these attributes warrants further investigation.

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Effect of nitrogen fertilizer on the yield and the weight proportion of legumes to the yield (legume ratio) in timothy (Phleum pratense L.) dominant meadows at the eastern part of Hokkaido was investigated, and the optimum application rates of nitrogen fertilizer was determined on the basis of legume ratio. Meadows tested were classified into five types; Timothy with over 30% of red clover (Trifolium pratense L.) and white clover (Triforium repens L.) mixture (Type 1), timothy with 30-15% of white clover mixture (Type 2), timothy with 15-5% of white clover mixture (Type 3), timothy pure sward (Type 4), and Kentucky bluegrass (Poa pratensis L.) and red top (Agrostis alba L.) dominant meadow (Type 5). 1) Total yield of timothy and legumes increased with increasing application rates of nitrogen fertilizer for all types. Under 16kgN/10a/year application, total yield was affected by legume ratio and the highest yield at the same rates was always obtained in Type 1, followed in descending order by Type 2, Type 3, Type 4 and Type5. 2) Legume ratio decreased with increasing application rates of nitrogen fertilizer and further decreased in the subsequent years. 3) Each of the amount of nitrogen absorbed by the sward, fixed by legumes and transferred from legumes to associated timothy was much more in the type with high legume ratio than in the type with low legume ratio. Nitrogen transfer increased with increasing application rates, though, the amount of nitrogen fixed decreased. 4) In order to obtain the target yield in this area (4.5t/10a, fresh weight), as well as to maintain the present legume ratio, the optimum application rates of nitrogen fertilizer were about 4, 6, 10, 16kgN/10a/year for Type 1, Type 2, Type 3, and Type 4, respectively. In Type 5, however, it was impossible to obtain the target yield without renovation.

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It is known that dead grass roots and subterranean stems are accumulated on the ground in permanent grassland. This is called root mat. This report describes the situation at the surface layer of permanent grassland with differences in age and land utilization such as grazing and harvesting. Results obtained were as follows: 1. Root mat in the pasture was divided into three layers depending upon the composing materials and the thickness of the topmost layer which increased with age. 2. Both the number of individuals and species of soil fauna was greater in the meadow compared to the grazing pasture regardless of age. 3. The soil hardness at the topmost layer was the greatest of all measured values on a more than 20-year old grazing pasture. 4. The soil resistance in the grazing pasture measured by a soil penetrometer was maximum in the layer between 0 to 1cm deep for each category. This peak value in soil resistance increased with age.

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Direct cut (A) and wilted (B) silages were made from Italian ryegrass (Lolium multiflorum Lam.) at heading stage in air-tight pilot silos and the changes in weight and composition of material during storage were estimated by a vinyl bag technique. The contents of dry matter (DM) and crude protein (CP) in ensiled grass and resultant silage were determined with analytical sample prepared by the methods of oven drying (OD) and freeze-vacuum drying (FV), respectively. And the nutrient recovery based on both methods was calculated from the amounts of ensiled grass and obtained silage and from the contents of nutrients in the grass and silage. Furthermore, the rate of stored digestible nutrients to ensiled nutrients was evaluated with the values of nutrient recovery and of digestibility by wethers of the silage. Mean scores by FLIEG's method of resultant silages were 16 in A-silage and 56 in B-silage and the contents of volatile matters were appreciably higher in A-silage, when compared with those in B-silage. Although the crude yield by weight was no marked difference between the silages, the recoveries of DM and CP in B-silage were considerably higher compared to those in A-silage. On the other hand, the contents of these nutrients in the silages determined by the FV method were significantly higher (p<0.01) than those determined by the OD method, whereas such tendencies were not detected in ensiled grass. The recoveries of DM and CP evaluated based on each method clearly reflected the nutrient contents in the silage and the values evaluated based on the FV method were significantly higher (p<0.01) than those based on the OD method. In addition, the digestibilities of DM and CP in the silages were significantly higher (p<0.01) in the values by the FV method than those by the OD method. Consequently, the difference between the drying methods for analytical sample in recovery rates of digestible nutrients increased markedly. From these experiments, it was confirmed that the estimates of nutrient losses during storage were considerably influenced by the methods used for the drying of analytical sample of silage.

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Big round bales were prepared at two levels of moisture contents (37% and 24%) in order to investigate their heat damage. The central part of the big round bale prepared at 37% moisture content, which showed temperature rise of reaching up to 56℃, was assigned to the high temperature section. The circumference of the high temperature section was assigned to the middle temperature section. The low temperature section was decided to be the bale prepared at 24% moisture content, which showed the temperature of 31℃ at 4th day after baling. The experimental results were as follows. 1. Contents of ADF, NDF, hemicellulose, cellulose and lignin lowest at the high temperature section. Values of ADIN/T-N and NDIN/T-N were the highest at the high temperature section, showing 15.0% and 51.0% as compared to 14.4% and 33.1% at the middle temperature section and 11.6% and 19.4% at the low temperature section, respectively. 2. At the middle and high temperature sections, crude protein digestibility was lower, but digestibilities of dry matter, organic matter, ADF, NDF, hemicellulose, cellulose and energy were higher as compared to those at the low temperature section. Crude fat digestibility was the highest at the high temperature section. Contents of TDN and DE were the lowest at the low temperature section, but content of DCP was the highest at the low temperature section. 3. Ammonia-N concentration in the rumen of the sheep fed on hay of the high temperature section kept its level almost always lower than those of the other two sections. Total VFAs concentration in the rumen of the sheep fed on hay of the high temperature section was almost always higher than those of the other two sections. 4. Faecal N output became larger and urinary N excretion smaller when the sheep were fed hay of the higher temperature sections in the bales. Though retained N was the largest at the high temperature section, the difference among the sections was not statistically significant.

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Hay and silage of Italian ryegrass and of its pressed cake were fed to goats to study the effect of removal of some nutrients by green crop fractionation on the mineral balances and possible relations with hypomagnesaemic tetany of ruminants. Four kinds of feeding material prepared were; Italian ryegrass hay (RH), Italian ryegrass silage (RS), pressed cake hay (PH) and pressed cake silage (PS). And 4 head of Shiba strain goats were used for 4×4 Latin square design. Urine, faeces and blood samples were taken and analysed. The reduction of the concentration of potassium during the process of green crop fractionation was 1.6 times greater than that of magnesium. The faecal magnesium and urinary potassium wre main routes for both excretions and they were less in goats fed on PS and PH than in those fed on RS and RH reflecting the different intakes. Despite of lower intake of magnesium, the goats fed on PS and PH excreted more magnesium in urine than those fed on RS and RH suggesting the increased utilization of dietary magnesium in the former. The RS and RH were higher in potassium concentrations and its intakes than PS and PH. The lower potassium concentration of PS and PH resulted in the higher utilization of dietary magnesium. But there remains a possibility of effects of some other components removed during the preparation of pressed cake. As a conclusion, the favourable effect of feeding Italian ryegrass pressed cake on magnesium utilization of ruminants was certified.

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Pasture fences, being important in cattle grazing and the pasture management, have suffered many snow damages in the snowy area. It is necessary to grasp the factors to reduce these damages. The experimental fences were constructed mainly on the flat pasture, Noheji in Aomori, with the three kinds of posts; e.g. V, W and U shape posts in the cross section, with the three kinds of wire; e.g. rounded, barbed and high tensile barbed wire, and with the three kinds of post spacing; e.g. 4, 6 and 8 meters. The standard fencing structure had 4m post spacing, 4-barbed wire with 40, 70, 100 and 130cm in height above the ground and the 45cm depth dropped into the ground. The wire were fixed completely on the posts with the short wire. After wintering, the structural changes of fences were investigated. The experiment was carried out under the maximum snow cover of 150cm. The soil bearing capacity was rather high because of being gravel and sand below 15-35cm in depth. The results obtained are as follows; 1) All corner posts were inclined toward inside by the snow force. When the corner angles set to 90 degrees, the inclination angles were in the increasing order of U shape, V shape and W shape, the order of which agree with the sizes of the modulaus of section of each post. This tendency is just attributed to the dynamic property of the posts. Therefore we should use the post of dynamically bigger modulus of section if post's price is equal. 2) It is generally said that the plane angle in the corner fences influences the inclination angle of corner post, and is one of the important points for the fence construction. At this experiment, however, it was not clear whether the inclination angle of corner post was influenced by the plane angle or not. 3) The snow force made the wire slackened and/or broken. In case of the snow cover over 150cm, it was found significantly at 0.1% level that the wire slackening in 4m post spacing became bigger as the wire was upper, and the rounded and barbed wires were broken at upper wire position but the high tensile barbed wire was not. From these results, in the maintenance of fence in the snowy area, it should be avoided to fix the wire firmly on the posts by the short wire, and it should be better to use the stronger wire such as the high tensile barbed wire for the fence construction.

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The mountainous sloping pasture has been mostly used for the beef cattle. Pasture fences, enclosing the grazing cattle, have suffered many snow damages in the snowy area. It is important to grasp the factors to reduce these damages. Thirteen kind of experimental fences were constructed on the sloping pasture, Noheji in Aomori, with the slope of 15 degrees. The standard structure had the corner post, in the middle of 4 span's fence with the corner plane angle of 90 degrees, 4m span and 45cm depth dropped into the ground. The 4-barbed wire at 40, 70, 100 and 130cm in height above the ground were fixed completely on posts with the short wire. The maximum snow cover was 90cm in the upper side of slope and 125cm (estimated cover) in the lower side, and the soil bearing capacity was as low as 11-15kgf/cm^2. After wintering, the structural changes of these fences were investigated. Results obtained are summarized as follows; 1) All of corner posts were inclined to the lower side of slope. It was found significantly at 1% level that the slanted angle of corner post increased as the snow cover at the corner post was deeper, and that the wire slackening increased as the mean snow cover at the posts was deeper. After the wire were pulled down by the snow setteling force and the snow creeping force on the slope, the corner posts were inclined, especially many of corner posts constructed at upper slope were pulled out, and the wire were slackened as the results. 2) To prevent the snow damage, it is necessary to use the high tensile wire, not barbed wire but round wire which provide an easy maintenance of fences, and to use the bigger and strong posts for the corner and end posts which received the bigger force such as the snow force, the wire tension and the cattle pushing force.

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The experiments using pasture fences with different structures were carried out to grasp the difference of grazing behavior of heifer calves outside the fence line. The 4-barbed wire fences had the post spacings of 4, 5 and 6m, for which three types of fence were designed; the conventional type with the wire height of 30, 60, 90 and 120cm above the ground, the experimental fence type I with the wire height of 30, 55, 80 and 120cm, the experimental fence type II with the wire height of 30, 50, 75 and 110cm. In three series of sward height; 60-70cm, 30-40cm and 20-30cm, the super heavy grazing was made by 24 heifer calves with mean withers height of 110cm during 15 hours overnight in the pasture of 240m^2 surrounded by the fences. The grazing behavior outside the fence through the wire space was found at a long distance from fence line as the post spacing became wide. In 60-70cm sward pasture, the differences of fence types were clear. The effects of fences on the grazing behavior outside the fence were especially found in the type I of 4m post spacing and type II of 4 and 5m post spacing, for which the wire space at 30-80cm above the ground was narrowed. However, these differences were not clear when the sward height of the pasture was below 40cm. It was not found that the wire slackening increased as heifer calves grazed at longer distance from fence line. In any case, these fence controlled the cattle escaping from fence.

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