Experiments to determine grassland features using spectral characteristics were performed. Spectral reflectance was measured, using a hand-held spectrometer, at 102-151 random points in five Italian ryegrass(Lolium multifeorum Lam.)meadows under different vegetation conditions. The measurements were used for three applications:1)to visualize the relationship between red and near infrared spectral characteristics, 2)to determine the spatial pattern of aboveground biomass and apply it to gamma distribution, and 3)to determine the spatial pattern of plant coverage. The red-near infrared spectral reflectance relationship that was derived was a brief and clear index for the degree of dense or sparse coverage or the area of bare soil in grassland. Analysis of the biomass and coverage histograms determined different patterns for different plant growth or grassland conditions. Biomass distribution could be determined more accurately, both qualitatively and objectively, by applying the gamma distribution. Thses results suggest that several kinds of grassland features could be determined in a short period of time using spectral data measured with an hand-held spectrometer.

View full abstract

The dry matte(DM) degradation and its seasonal changes in eleven mulberry varieties ware determined using the nylon bag technique. The leaves were harvested on 6 July, 25 August and 23 October. Degradability was measured by incubating samples in the rumen of two fistulated Holstein cows for 4, 8, 12, 24, 48 and 96h. The degradability of the readily soluble fraction(a)rabged between 6.9-34.4% in July, 27.2-49.6% in August, and 33.6-44.5% in October. The corresponding values for the slowly degradablw fraction(b)were 61.5-87.0, 44.7-67.6 and 53.5-63.2%, respectively. The potential degradability(PD=a+b)and rate of degradation of b per h(c)ranged between 91.1-97.2% and 8-16%/h, respectively and were not significantly affected by time of harvesting and varieties. Both factors significantly affected effective degradability, which was 79.2, 81.9 and 84.8% in July, August and October, respectively, and varied between 75.0-89.5% among the varieties. The results of this study suggested the existence of varietal differences in degradability among the mulberry varieties. However, the leaves of all the mulberry varieties tested were highly degradable and therefore can serve as suitable supplements to low quality basal grass diets.

View full abstract

A comparative RAPD analysis was performed on apomictic and sexual lines of guineagrass to identify their mode of reproduction. The lines tested included apomictic autotetraploid(2n=4x=32)cultivars "Natsukaze", "Natsuyutaka" and "Ku 5954" and the tetraploid sexual line "Noh PL 1". In addition, diploid(2n=2x=16)sexual line "GR 297" and three progeny of a triploid hybrid(2n=3x=24)were also evaluated. Of the 16 primers(Operon RAPD decamer primers)tested, eight produced band patterns which clearly discriminated between the apomictic and sexual line. The three lines of apomictic origin displayed different patterns;however, the data derived from individual plants within the three lines were identical. In contrast, individuals belonging to the two sexual lines consistently showed different patterns within and between the two lines. Three progeny of a triploid hybrid had identical RAPD banding patterns through the experiment. Thus, the triploid hybrid was predicted as apomictic propagation. Microscopic embryo sac analysis confirmed the mode of reproduction in the genotypes tested as revealed by RAPD banding patterns. This research suggests that RAPD analysis is suitable for the identification and discrimination of apomictic and sexual lines of guineagrass.

View full abstract

Effects of brown midrib(bmr-18)and bloomless(bm) genes on the resistance to sheath blight were investigated in a field inoculation test by using an F_2 population of the cross between "F_6-3A-5"(bmr-18/bmr-18;bm/bm)and "74LH3213"(Bmr-18/Bmr-18;Bm/Bm). The plants in the F_2 population were classified according to their phenotypes:normal(N), brown midrib(bmr-18), bloomless(bm) and brown midrib and bloomless(bmr-18+bm) types. There were no remarkable differences among these types in the height of flag-leaf collar(HF), heading date which may affect the result of resistance to sheath blight in the inoculation test. However, the height of lesion(HL) relative to the height of HF(RLH) in the bm and bmr-18+bm types were significantly shorter than those in the N and bmr-18 types. In addition, there was no significant difference between bmr-18 type and N Type in the HL and RLH data. These results suggest that the bm gene increases the resistance to sheath blight, and that bmr-18 gene have no negative effects on the resistances to sheath blight. Furthermore, varieties which are resistant to sheath blight and also possess higher nutritive values can be developed by using bm and bmr-18 genes.

View full abstract

Pleioblastus chino var.viridis can dominate under severe grazed conditions. To understand the reason for this dominance, we investigated the dry matter composition ratio of each part in the plant body and dry matter production in two plots;grazed and ungrazed. Leaf production and grazed mass during a grazing period were estimated using a regression formula between the standing crop of leaf and the leaf increase rate. The dry matter composition ratio of rhizome in the grazed plot was higher than that in the ungrazed plot. On the other hand, the ratio of stem in the grazed plot was lower than that in the ungrazed plot. The ratio of leaf in the grazed plot was almost equal to that in the ungrazed plot during the grazing period. Annual net production in grazed and ungrazed plots was estimated at 670gDM/m^2 and 647gDM/m^2, respectively. From the obtained results, we consider as follows. The increase in composition ration of rhizome under grazed conditions has the advantage of increasing the security of the bud and the storage of reseve substance for regeneration of leaves after a disturbance. Thus, the increase in the ratio of rhizome with the decrease in stem contributed to active leaf production and high annual net production. The high net production under grazed conditions enabled the dominance of P.chino var.viridis to occur.

View full abstract

Under rotational grazing of lactating dairy cows, effects of grass height at a start of a grazing season on herbage production and utilization were studied. Experimental pastures were two of 0.94ha, and each was rotationally grazed by 6 lactating dairy cows for 5 hour everyday from May to October. Mean grass height at the start of the grazing season in each pasture was 15cm(S15)and 20cm(S20). Herbage allowance was fixed through the grazing season, and daily paddock area was adjusted according to the each herbage yield. At June, grass height in S20 was higher than S15(P<0.01), and leaf weight and intake in S20 tended to be higher than S15. The sheath length of grass and the amount of dead material in S20 tended to be higher than S15. From June to August, the herbage regrowth in both paddocks decreased, particularly decreased largely in S20. After July, the leaf proportion to the herbage mass in S20 tended to be lower than S15. From July to September, the intake in S20 tended to be lower than S15, while total herbage utilization in each paddock was 8.6tDM/ha, respectively.

View full abstract

We propard laboratory-scale silages of tofu cake and brewer's grain mixed with or without Italian ryegrass(Lolium multiflourm Lam.)or alfalfa(Medicago sativa L.), irradiated them with gamma rays prior to storage and examined the microflora and fermentation quality of them. 1)Spore-forming bacteria, which can cause butyric fermentation of silage, molds and yeasts, which can cause aerobic deterioration of silage, were eliminated from the silages with doses of 8kGy, 4kGy and 16kGy, respectively. Aerobic bacteria in the silages decreased to less than 10^3 cfu/g with a 16kGy dose. Irrespective of gammairradiation, fow yeasts were detected from the silages containing alfalfe. 2)Among the silages exposed to a 16kGy dose, the silages containing brewer's grain contained the largest amounts of lactic acid and were of the lowest pH. The lactic acid bacteria in them lost ability of colony formation with the 16kGy dose but kept lactic acid producticity. These results suggest that a 16kGy dose are necessary to inhibit butyric fermentation and aerobic deterioration of silage and that addition of brewer's grain in the ensiling process may improve the fermentation quality of the irradiated silage.

View full abstract

Moisture is a major component of fresh herbage. We studied seasonal changes in yield and the nutrient and moisture contents of Orchardgrass(OG, Dactylis glomerata L.), Tall fescue(TF, Festuca arundinacea Schred.), and Perennial ryegrass(PRG, Lolium perenne L.)in swards with three different grass lengths(20, 30, 40cm)to determine whether the dry matter and nutrient intake of grazing animals were restricted by forage moitsure. The moisture content in the grasses was higher for short sward heights than for long sward heights, except for OG in summer. Dry matter yields increase with sward height, but most occur in the lower part of the canopy. The spatial distribution of the standing crop in the canopy does not favor dry matter ingestion by grazing animals, because they are unable to graze on the grass in the lower part of the canopy. Furthermore, the plant tissues with high moisture content are in the upper part of the canopy, and grazing animals are obliged to ingest the high-moisture forage. Consequently animals necessarily ingest laege quantities of water as grass moisture, which leads to restricted dry matter and nutrient intake. The grass moisture is held in the plant tissue, and is not released in the animal gut unless the plant tissues are destroyed by mastication or ruminal digestion. This study suggests that if animals grazed on shorter swards, grass moisture might restrict animal dry matter and nutrient intake.

View full abstract

Field tests conduced between 1996 and 1997, using 21 commercial varieties of corn(Zea mays L.), examined varietal variations in nutrient concentrations with differing potassium application. Significant differences and correlated relationships between 1996 and 1997 were observed in the concentrations of K, Ca, Mg, N, P and the K/(Ca+Mg)equivalent ratio. The equivalent ratio was enhanced by increased application of K with varietal means ranging from 1.4 to 2.1 in annual experiments. Variation found in the ratio can be explained by differences observed for Ca and Mg concentrations which were laeger than that for K. The results indicate that selection of varieties with smaller equivalent rations is possible. For those nutrients that have low utilizing effciences, such as Ca, Mg and P, significant positive correlations between concentrations in the plants and uptake were found. This selection will be useful for the effective use of fertilizers.

View full abstract

It was confirmed in a previous paper that M.avium subsp.paratuberculosis was killed when kept in a high moisture silo with low pH value and high lactic acid content. In the present paper, effects of storage on survivability of M.avium subsp.paratuberculosis in low moisture-or ammonia-treated silages containing less organic acid and having a high pH were investigeted in 2 kinds of pouched silages. Pouch silos containing sterilized ground alfalfa hay and a piece of filter paper onto which M.avium subsp.paratuberculosis suspension had been applied were made at moisture levels of 75, 60, 45, 30 or 10%, with lactic acid bacteria added at the time of ensiling. The other pouch silos containing the same materials were made with 30% moisture, and 1 or 3% ammonia added at ensilaging. Though the count of M.avium sub sp.paratuberculosis in the pouch silos with moisture of 60% or more, low pH and containing high lactic acid decreased below the detectable level, bacteria in pouch with 45% moisture or below, containing less lactic acid with a higher pH survived after 14 days incubation at 30℃. However, the count of M.avium subsp.paratuberculosis in the pouch treated with 3% ammonia decreased below the detectable level, while in the pouch treated with 1% ammonia, it also decreased and some bacteria survived. The above results suggest that low moisture silage, hay and roughage treated with 1% ammonia made from grass or forage crop that are contaminated with M.avium subsp.paratuberculosis, might be a cause of Johnes' disease. When grass on a forage crop possibly contaminated with M.avium subsp.paratuberculosis must be fed, it is suggested that it should be stored as high moisture silage at low pH with added fromic acid, or low moisture roughage treated with more than 3% ammonia.

View full abstract