The objective of this study was to compare the differences in the weeding and pest control roles of Indian Runner(IR), Chinese native duck(CN) and crossbred ducks(Mallard x Khaki Campbell : F_1) free-ranging in paddy fields. During June to September in 1996-1997,weed growth, pest insect infestations, and the number of the insects ingested by free-ranging ducks were examined. 1. It was found that in July 1997 three duck breeds were able to control weed growth significantly. Chinese native duck showed a higher ability to control weeds than F_1 in paddy fields, where a lot of weeds (especially, Echinochloa crus-galli P.Beauv. var. oryzicola Ohwi and Echinochloa crus-galli P. Beauv.) were found in August 1997. 2. It was also found that white-backed and brown planthopper infestations were controlled by 3 duck breeds in the experimental period, however there were no differences in the pest control capabilities among 3 breeds. An experiment in July 1996 measuring the number of pest insects in pseudo-crops, glandular stomachs and gizzards of the ducks after free-ranging in a paddy field for 80 min., showed that F_1 , IR and CN ingested 336,732 and 506 white-backed planthoppers per duck, suggesting a significant effect on pest control. The green rice leafhopper infestations were not controlled by 3 duck breeds. 3. Three duck breeds also significantly suppressed an infestation of big mud snails in the paddy fields, however there was no significant difference in the population of big mud snails among 3 breeds. On the other hand, the abilities of Fl and CN to supress big mud snail eggmasses were higher than that of IR. These results indicated that CN had a higher ability to control weeds and pest insects in paddy fields comparing with F_1 and IR.Jpn. J. Livest. Management, 34(1) : 1-11,1998 Received January 16,1998 Accepted May 6,1998

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The present study was conducted to examine the effect of integration of aquatic fern Azolla and the Aigamo ducks on weeding, pest control, and behaviour of the Aigamo ducks in paddy fields. The paddy fields were allocated into 5 treatments, named : agrochemical (standard fertilizer, herbicides and pesticides were used), control, Aigamo ducks, Azolla and Azolla-Aigamo ducks plots. The experiments were carried out during 1996-1997. Azolla was inoculated into the paddy fields the day after rice transplanting at the rate of 70g/m^2 in 1996 and 25g/m^2 in 1997. After the Azolla was grown for 6-7 weeks, the biomass was plowed into the soil or submerged due to the stirring behaviour of the Aigamo ducks. Aigamo ducks (6ducks/3a) of I week of age were introduced into the paddy fields I week after rice transplanting, and then they were free-ranged for 2 months until the rice was in ear. In August and September of 1996,the emergence of weeds in the Azolla-Aigamo ducks and the Aigamo ducks plots was significantly less than that of control. In August of 1997,the emergence of weeds in the Azolla-Aigamo ducks plot was significantly less compared with the other plots, except for the agrochemical plot. Echinochloa crusgalli was effectively suppressed by a thick Azolla mat, Cyperus difformis, L.perocumbens and R. indica var. uliginosa were foraged by the Aigamo ducks. It was suggested that the weeding effect in Azolla-Aigamo ducks plot was due to the integration of Azolla and the Aigamo ducks. In the early period of the rice culture, the infestation of Sogatella furcifera in plots with the Aigamo ducks was significantly smaller when compared to the plots without the Aigamo ducks but the infestation of Nilaparvata lugens in plots with Azolla was higher than the Aigamo ducks plot in the late period of the rice culture. There was no significant effect on the control of Nephotettiz cincticeps by the Aigamo ducks. It was indicated that the infestation of pest in the late period of the rice culture was dependent on the time of plowing the Azolla. The Aigamo ducks in the Aigamo ducks plot engaged in foraging at night, whereas those in the Azolla-Aigamo ducks plot did so during the daytime. Comparing the Aigamo ducks plot, the Aigamo ducks in the Azolla-Aigamo ducks plot spent distinctly less time on foraging and moving behaviour for 24 hours, however, it was observed that ducks in this plot spent more time on resting behaviour. Jpn.J.Livest. Management, 34(1) : 13-22,1998 Received March 26,1998 Accepted May 13,1998

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In order to obtain the fundamental data for utilizing competent bacteria which are able to disassimilate the substances of offensive oder in animal intestine contents, the amounts of ammonium, stinking sulfur compounds and fatty acids of short chain remaining in porcine intestine contents were analyzed. Some physiological indices of the contents were also determined. The contents were picked up from six parts of swine intestine; that is jejunum, ileum, caecum, centripetal and centrifugal parts of colon, and rectum. Dissolved oxygen in the contents significantly decreased to 0.40-1.10ppm during the content transport through the intestine. The pH values of the contents changed to lower ranges in caecum, which reflected a formation of fatty acids by microorganisms predominantly inhabiting there. Ammonium-N in the contents increased to 750-1,200mg/l during the transport from caecum to rectum. Hydrogen sulfide and methanethiol were recognized at levels lower than 10mg/l and rather increased during the transport. Acetic acid, propionic acid and butyric acid were abundantly formed in caecum (2,400-3,600mg/l) and thereafter showed sluggish descents in centripetal and centrifugal parts of colon. Iso-butyric acid remained more little limited. Normal-valeric acid and iso-valeric acid remained in much lower levels, but had increasing tendencies in centripetal part of colon. Jpn. J. Livest. Management, 34(1) : 23-28,1998 Received January 22,1998. Accepted May 14,1998.

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As one of forms of complex system of forestry and animal production, studies were made on a forest-pastoral system under Quercus acutissima CARR. trees (nine years after planting the seedlings; 1,492 standing trees/ha). In this report, characteristics of air temperature, solar radiation and pasture composition under Quercus acutissima CARR, trees in Shiba village was described. 1. Daily mean air temperature was not different between under and outside of the Quercus acutissima CARR. trees canopy. However, during the period when Quercus acutissima CARR. is in leaf (spring to autumn) daily maximum temperature was lower, and minimum higher, under the trees canopy than the outside of it. 2. Relative values of solar radiation at the forest floor under Quercus acutissima CARR. trees to that in the open area varied with season, ranging from 100 % in April to 25-35% in September. In contrast, under Cryptomeria japonica D. DON (ten years after planting of seedling; 1,800 standing trees/ha), relative solar radiation was constantly lower than those of under Quercus acutissima CARR over the same period, ranging from 10-20%. 3. Grazing of the pasture by cattle under Quercus acutissima CARR, trees degraded Miscanthus sinensis Andersson var. sinensis, and increased the coverages of Poa sphhondylodes Trine, Carebreviculmis. R. Br. and Paederia scan dens (Lour.) Merrill var. mairei (Reveille) Hara. Orchard grass (Dactyls glomerata L.), which was the only sown grass in the pasture under Quercus acutissima CARR. trees. Jpn. J. Livest. Management, 34(1) : 29-36,1998 Received December 15,1997 Accepted May 18,1998

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