To study a potential aversive effect of Euphorbia supina and Euphorbia maculata on preference of feed by sheep, 4 ewes were used in 2 trials for determination of dry-matter intake and selection behavior for a mixed feed composed of wheat bran and one of two potential weeds with diverse proportions. Ewes were offered oats hay ad libitum as a basal diet for 176 days. For trial 1, Euphorbia supina was mixed with wheat bran at rates of 0, 5, 7, 10, 25, 50 and 100%. For trial 2, Euphorbia maculata was mixed at rates of 0, 10, 15, 20, 25, 50, 60, 75 and 100%. With these mixed feed, feeding behavior of ewes were observed at the interval of 3 days. A 20 g of each mixed feed was offered to ewes immediately before morning feeding for 20 min., and the behavior was recorded by video-recorder. Dry-matter intake was determined by the difference of weight at the before and after feeding by using a digital balance (weighing precision ; 0.1 g). The figures less than 1g were considered to be 0g intake. In addition, the behavior of ewes on basal diet was also recorded for 24 h.
Proximate composition of oats hay, E. supina and E. maculata were as follows : crude protein, 7.3, 11.8 and 5.6% DM ; neutral detergent fiber, 55.9, 28.3 and 40.6% DM ; acid detergent lignin, 4.1, 5.9 and 10.8% DM, respectively. At the end of each trial, ewes increased their weight. Mean environmental temperature ranged 15 to 27°C. Mean dry-matter intake of hay was 1.8±0.1 kg for trial 1 and 1.4-1-0.1 kg for trial 2 and tended to decrease as the environmental temperature increased. Ewes on a basal diet in the present study, therefore, were considered to be in normal feeding condition.
Ewes refused to eat the mixed feed with 10% of E. supina or over. Three ewes out of 4 ingested the mixed feed with 5% and only one ewe ate 7% feed. The exploratory behavior for feed tended to be longer in feed with 10% of E. supina or over. As for the mixed feed with E. maculata, feed aversion was found for 75 and 100% feeds. Three ewes ingested a small amount of feed of 60%. The exploratory behavior for feed was only found in the case for 75 and 100% feeds.
From the results of the present study, it was concluded that E. supina produced feed aversion at the levels between 7 and 10%, while E. maculata caused feed aversion at the levels between 60 and 75%. These differences in feed aversion may be responsible for the difference in levels and/or kinds of terpenoid contained in both weeds. Further works need to clarify its cause and effect.

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The grazing ability and the behaviour of sheep on tethering were observed for the purpose of investigating the potential of sheep for weed control.
One relatively submissive type ewe and another relatively nervous type ewe were used for tethering. Ewes were tethered on 2 m of rope each a short distance apart using dog collars to keep them safe from twining each other's rope. Tethering started at 10 : 00 and finished at 15 : 00, and was repeated six times. Ewes were kept in a pen from the evening of the day before the tethering, given only water. The behaviour of sheep on tethering was recorded by a video-recording system. Grazing behaviour, drinking behaviour, resting behaviour, and investigative behaviour were investigated. A previous measurement was done on the amount of feces and urine of sheep during a five-hour span using three ewes with paper diapers, and repeating the procedure twice while pasturing.The amount of grazing during tethering was estimated from the body weight increase and the amount of feces and urine during the five hour time period.
Sheep 1 and sheep 2 showed 3.35-4.57 hours and 3.03-4.55 hours of grazing behaviour, respectively. The means of grazing bout duration of sheep 2 were 0.6-2.1 minutes, showing a tendency to be shorter than that of sheep 1. The resting behaviour count of sheep 1 (the relatively submissive type) was observed to be 1-3 times for each observation except for the fourth observation. However, resting frequency of sheep 2 (the relatively nervous type) was just twice only on the second observation, with no rests observed any other time. From the first to the fifth observation, sheep 1 and sheep 2 showed cautious and investigative behaviour 0.4-6.6 times and 6.6-27.8 times per hour, respectively. The body weight increases during five hours' tethering were 3.0-4.8 kg for sheep 1 and 1.2-6.8 kg for sheep 2. During the first three observations, sheep 2 showed only a little body weight increase. Both ewes grazed enough on the fourth observation and the estimated amounts of grazing were 5.5 kg for sheep 1 and 7.5 kg for sheep 2, respectively. Sheep 2 (the relatively nervous type) seems to have become accustomed to tethering and to have grazed enough since the fourth observation. Although it was somewhat noisy on the sixth observation, the estimated amount of grazing for sheep 2 was 3.7 kg.
These results showed the utility of tethering sheep for weed control, demonstrating that sheep became accustomed to a tethered situation faster by tethering two sheep a short distance apart, although there were some differences on the adaptability to tethering. They grazed well as much as 4 kg during five hours' tethering in the daytime.

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This experiment was carried out to examine the effect of safflower oil on control of methane emission from expiratory gas and on the relationship between digestibility and characteristics of rumen liquor. Four sheep (55 kg in average body weigh) fitted with rumen fistula were used for this experiment. Animals were fed with concentrate and roughage (Italian ryegrass hay chopped at the length of 2 cm) under 18-20°C in environmental temperature i.e., feeding condition was set 2 : 8 in the ratio of roughage and concentrate, and fed with 80% of ad lib. feeding in the amount of diets, respectively. Safflower oil contained 74.3% linoleic acid of fatty acid composition was supplemented at 0% (control), 2.5%, 5.0% and 7.5% to the diets. Feeding trial was conducted with 4 × 4 Latin square method. Methane emission from expiratory gas was lower in safflower oil supplement than control. As the result, decreasing rate of methane emission from expiratory gas increased with the supplement rate of safflower oil and indicated the range from 14.0 to 47.9. By supplement of safflower oil, digestibility of fibrous components decreased but crude fat digestibility increased. Total digestible nutrients increased significantly in safflower oil supplements. Though the difference of pH in rumen liquor was small among four treatments, NH₃-N concentration changes at low level by safflower oil supplement. Total volatile fatty acid concentration of rumen liquor changed similarly in four treatments. The ratio of acetic acid to propionic acid, however, changed low by supplement of safflower oil. Linoleic acid of rumen liquor changed low after feeding in all treatments. It was shown that there were control of the methane emission from the expiratory gas and improvement effect of nutritive value by safflower oil supplement to the diets.

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