The simple cellulase digestion method, in which in vitro dry matter digestibility (IVDMD) of the samples kept original form of leaf (using fresh leaf in this study) is determined by one-stage cellulase digestion technique, was examined. With simplifying digestion procedures and sample preparation, IVDMD values of fresh leaf by simple cellulase or rumen digestion were smaller than IVDMD of dried and ground samples by 2-step cellulase digestion (Table 1) and would not be similar values to in vivo dry matter digestibility, although IVDMD of simple cellulase digestion correlated well with those of 2-step cellulase digestion (Table 5). Despite of lower IVDMD of fresh leaf, differences among IVDMD of genotypes were larger for fresh leaf by simple digestion methods than for dried and ground samples by 2-step cellulase digestion method (Table 1). From the above aspects as well as simpler procedures, simple digestion methods, especially using cellulase, would be better for evaluate the potential values of plant selection than 2-step cellulase digestion methd. The reports on relationships of digestibility for two pairs of near-isogenic lines ; bloom and bloomless Combine Kafir 60, and brown midrib-18 and Normal-18, supported our results of digestibility by 2-step cellulase digestion and two kinds of simple digestion methods, except for a few cases in simple rumen digestion method. In addition to this discordancy in simple rumen digestion, from the results of ANOVA in Table 3 and 4 and correlation coefficients in Table 5, the simple cellulase digestion method is considered to be superior to the simple rumen digestion method. From the results in Table 4, 5 and 6, the selection at young seedling stage would be expected, though IVDMD of fresh leaf at flag leaf were the best for selection at present. Moreover, the scoring method of red-stained digestion area will be the other possibility for easier selection of large numbers of genotypes.

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The growth analysis of Italian ryegrass population was executed on the basis of equations (Logistic) of growth regressive curve in seasons of autumn, winter, and spring. Obtained results are as follows. 1) CGR_max and average productivity max (Maximum value for dry matter yield/regrowth period) showed different values in seasons, and when these values were indicated with average values of four years respectively, they were 25.8 and 13.4gm・^<-2>・day^<-1> in spring, 10.5 and 6.7 in autumn, and 7.9 and 5.4 in winter. 2) A close positive correlation (r=0.985) was recognized between CGR_<max> and average productivity max, as shown in the equation (1), despite of different experimental years and seasons. average productivity max≒0.433 CGR_<max> +2.13 (1) 3) Days to CGR_<max> and days to average productivity max showed different values in seasons, and when these values were indicated with average values of four years respectively, they were 28.4 and 39.2 days in spring, 39.8 and 55.3 in autumn, and 65.7 and 90.7 in winter. 4) A close positive correlation (r=0.998) was recognized between days to CGR_<max> and those to average productivity max as shown in the equation (2), despite of different experimental years and seasens. days to average productivity max≒1.367 days to CGR_<max>+0.687 (2) Namely, the period to average productivity max is about 1.4 times as long as that to CGR_<max>.

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To follow up quantitatively the metabolic fate of labino clover saponins ingested by herbivorous animals, the present experiment has been carried out using rabbits fed a synthetic diet containing the purified ladino clover saponins. Two male Japanese white rabbits weighing 3.1 and 3.3kg were placed individually in metabolic cages. For 18 days the rabbits received saponin-free diet (control diet) of 70g per day per head and during the last 6 days feces and urine were collected as control specimens. Following 6 days they were fed on control diet of 35g plus saponin-treated diet of 35g (saponin intake 525mg per day per head) and next 6 days on saponin-treated diet of 70g (saponin 1050mg per day per head). Through the period feces and urine were collected daily. Saponins and sapogenins excreted in feces were determined by densitometric thin-layer chromatography. Materials derived in urine were divided into three fractions, 1) ether-soluble and neutral fraction, 2) ether-soluble and acidic fraction, and 3) water-soluble fraction. Each fraction was determined by thin-layer chromatography and/or gas-liquid chromatography, and compared with each of control urine. The results obtained were as follows. 1) Quantitative determination of saponin in feces indicated that 86-90% of ingested ladino clover saponin disappered while passing through the digestive tract. 2) Sapogenins appeared 6-8mg in feces per day when received saponin 525mg and even its twice dose. 3) In the ether-soluble and neutral fraction of urine, ladino clover sapogenins were not detected. 4) In the ether-soluble and acidic fraction of urine of saponin-fed rabbits, four materials positive with Liebermann-Burchard reagent were detected. These materials, however, could not be detected by gas-chromatography. 5) The water-soluble fraction of urine was hydrolyzed by sulfuric acid. In the hydrolyzate, ladino clover sapogenins were not determined, but large amounts of unknown materials blackened by 50% sulfuric acid and heat were obviously detected.

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Using field grown five grass species, the regrowth after the autumn final cutting at different date, the reserve carbohydrate content of the living stubble tissue sampled six times from autumn to early spring, survival during winter and regrowth in spring were measured at the Kyushu University in Fukuoka, Japan. The final cutting at late September resulted in promotion of the carbohydrate accumulation following after the regrowth, and accordingly increased winter survival and the spring regrowth. On the contrary, the both cuttings at late October or late November, paticularly the former, severely decreased winter hardiness of all the species due to the consumption of carbohydrate reserved at the cutting date through the regrowth. The differences of winter hardiness among species were apparently attributable to the ability to accumulate carbohydrate in the stubble or the overwintering part. And ranking order for the ability of five species was dallisgrass (Dg)>makarikarigrass (Bp)>setaria (Ks)>Buffelgrass (Bg)≧green panic (Gp). The critical level of reserve carbohydrate in the stubble during winter season for overwintering in this district was assumed to be above ca. 10% as TNC or 4-5% as total sugars.

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Timothy (Phleum pratense L.) was cut at three different heights (0, 10 and 20cm) above ground level and then the sugar metabolism in the haplocorm during its regrowth was examined in this study. The mean fresh weight of a haplocorm after cutting varied with the cutting height. Two peaks of sucrose hydrolyzing activity appeared only in the haplocorms at 0 and 10cm cuttings. Each peak at 0cm cutting was higher than that at 10cm cutting. Each of two peaks at 0cm cutting appeared earlier than the corresponding peaks at 10cm cutting. Fructosan hydrolyzing activity attained maximum in about 20 days after cutting regardless of the cutting height, its increasing rate being in the order of 0, 10 and 20cm cutting. Fructosan decreased rapidly in the haplocorm at 0cm and gradually at 10cm, while rather increased at 20cm cutting, suggesting that fructosan content is inversely related to the fructosan hydrolyzing activity in the haplocorm.

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The previous paper reported that the characteristic pattern of the production of the pasture established on the mineral soil which was affected remarkably by the invasion of annual weeds, and it was considered that the phenomenon was largely dependent on the edaphic factors derived from the characters of mineral soil. The present paper dealts with the yield of nitrogen, phosphorus, calcium, potassium, magnesium and sodium on the same plots described in the previous paper. The results are summarized as follows: 1) In the yield of six elements, Italian ryegrass had a highly important role from April to Jnue, orchardgrass in July and August and then the annual weeds after September. The group of annual weeds consisted of Echinochloa crus-galli, Setaria viridis, Digitaria adscendens, D. violascens, Amaranthus retroflexus, A. blitum and Achyranthes japonica. The genus Digitaria with its high seedling vigor and high forage production dominated in the grassland excluded almost other plants from summer to autumn. The nitrogen yield of the annual weeds occupied about 50% in the total yield. 2) Nitrogen, phosphorus and magnesium concentrations of plants were affected by the fertilization, although there was negative correlation between magnesium content in plants and dressed potassium. The nitrogen concentration in plants was in the following order ; Trifolium repens>Dactylis glomerata>Lolium multiflorum>Amaranthus retroflexus>A. blitum>Digitaria adscendens>Setaria vilidis. 3) The yields of the phosphorus at the heavy fertilized plot (N 40kg, P_2O_5 20kg K_2O 40kg per 10a) and the light fertilized plot (the half of the heavy fertilized plot) were 5.4kg and 3.8kg P per 10a, respectively. The yield of phosphorus of the annual weeds occupied about 42% in the total yield. 4) Orchardgrass was the highest in the potassium concentration among plant species, Italian ryegrass followed, and the genus Digitaria was the lowest. Accordingly, the great invasion of the annual weeds in pasture lowered the equivalent ratio of potassium to calcium and magnesium in the plants production of pasture. 5) The calcium concentrations of the annual weeds were lower than that of the forages. The ratio of the calcium yield of the annual weeds to the total yield was only 16-30%. 6) Specific difference in the magnesium yields by the forage at the experimental plots having the high level and low level of potassium was shown, the former was 1.97kg, the latter was 2.33kg per 10a. The ratio of the yield of magnesium by the annual weeds to the total yield was shown within 36-53%. 7) The value of K/Ca+Mg milli-equivalent ratio in oats was increased considerably with the increase of dry matter in May. Accordingly, the feeding of dairy cattle by a large quantity of green oats in this season should be taken with a special care.

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Fertilizer management should be rationalized based on the knowledge of nutrient cycles. In Japan, however, the nutrient cycles in a pasture have been little investigated from a consistent view point of the relation among soil, plant and cattle, because a convenient method by which many respective knowledge about the subsystem and/or the pathway of the cycle can be combined as a pasture system has not been established. Then, this study was commenced considering that a way could be found out by the introduction of the mathematical system model. In this paper the improvement of grassland productivity by fertilization was discussed from the N-P-K cycles point of view. A model of nitrogen cycle was constructed and the numerical calculations were conducted. The results obtained were as follows: 1. In a grazing experiment on the volcanic ash soil in Nemuro district, Hokkaido, N-P-K fertilization improved the productivity of not only herbage yield but also heifer growth compared with only K fertilization. 2. On N-P-K cycles, 1) the cycling nutrients were mainly affected by standing crop, 2) the take-out nutrients were N, 14-16% ; P_2O_5, 3.5-4% and K_2O, 12-14% of the cycling nutrients and 3) the rate of nutrients retuned by excreta were N, 46-53% ; P_2O_5, 58-65% and K_2 O, 47-55%. 3. The role of N-P-K fertilization is considered to consist of removal of limitting factor due to low phosphorus supply, meeting a demand of nitrogen and covering the loss of the fertilizing effect of excreta in case of concentrated return. 4. A compartment model of the intraseasonal nitrogen cycle under grazing condition was constructed. The flow rates of nitrogen in the compartments which were consisted of heifer, grass, legume, feces, urine and soil were assumed to be expressed by a system of differential equations. The coefficients of the equations were determined by experimental data and/or empirical knowledge. The model gave a good fit to the observed principal values. 5. The computer numerical calculation to assess the nitrogen balance sheet of a pasture soil in the first year demonstrated that the returned nitrogen as available form was a little because of mainly slow release of nitrogen from dung pats.

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The effect of high and low selective grazing by Holstein steer calves on number of dung patches in grazing pasture, consumption, nutritive value and digestibility of dry matter ingested ; and changes in body parts and weight, were studied. A system of rotational grazing was followed ; one group steers was grazed about 30% (rapid rotational grazing-R system) and a second group about 70% (slow rotational grazing-S system) of the grazeable herbage in orchardgrass dominant pasture. Steers in R system consume the upper parts of herbage mainly, but steers in S system consume the whole herbage from upper to bottom of it. Dung patches in the pasture disappeared at one month after occurrence of its in the both grazing systems, and there were no difference of number of dung patches between the both grazing systems. There were no difference of DCP and TDN intake of steers between the both grazing systems in spring and autumn. But in summer, DCP and TDN intake of steers in R system were more than that in S system, especially DCP. There was no difference of digestibility of herbage ingested between the both grazing systems in spring and autumn. But in summer, the digestibility of herbage ingested in R system was higher than that in S system. This difference was caused by that the digestibility in R system did not almost change during seasons, but the digestibility in summer became lower than that in spring and autumn in S system. The growth of all body parts of steers in R system were more than that in S system, and the difference of body length of steers was much markedly. There was no difference of DG between the both systems in spring and autumn, but in summer, DG in R system was more than that in S system. The change of DG of steers corresponded closely with the nutrient intake, especially in summer.

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Calcium hydroxide and calcium carbonate contained in the materials of concrete silo wall have a property to neutralize the organic acid of silage. Teis study investigated the effect of this neutralization on chemical quality of high-moisture silage. 1) In the concrete tower silo, the chemical quality of silage near to the silo wall was inferior to that in the center of silo, but in FRP (fiber reinforced plastics) coated silo, such phenomena were not observed. 2) In the plastic silo, the wall of which was smeared with sludge of compost, the chemical quality of silage near to the silo wall was similar to that in the center, and both were not inferior to that of control silo. 3) In the plastic silo (a conserved period of 50-day) which was painted with lime milk on the wall after smearing, silages both from the wall and the central part were of high pH, low lactic acid, and high butyric acid as compared with non-treated silo. 4) It was admitted that the existence of lime constituents on the silo wall may be a factor deteriorating the chemical quality of silage near to the silo wall.

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