Tadashi Yoshimoto’s research while affiliated with Azabu University and other places

Behavioral changes of Japanese wild boars to the person in attendance during the pre-and post-farrowing periods were studied. Tests were carried out twice a week. Responses of 6 females to the attendant during the pre-and post-farrowing periods were recorded when he stood in front of the door of the farrowing pen for 10sec. The responses of wild boars when they watched the person were subjectively graded. The Friedman test was performed to clarify the difference of responses between the pre-and post-farrowing stages. In the pre-farrowing period, they showed affiliative behavior (not agonistic and not avoidance, like ignoring the person in attendance) or rather avoidance behavior. After farrowing, they tended to be significantly (P<0.01) agonistic (performed pawing, rush, head butting and vocalization of threat). However about two weeks after farrowing, they began to be affiliative to a human again.

In this study, an experiment was carried out to clarify the color perception in dogs. Two female Shiba breed dogs were trained using an operant conditioning method in which they pressed a switch with their muzzles in order to obtain some food, to discriminate between simultaneously presented colored and gray cards. The left and right positions of the two cards were shifted at random. After the dogs were fully trained, their color perception ability was tested on three primary colors, red, blue and green. The dogs were subjected daily to one or two sessions which consisted of 20 trials each.The criterion of successful discrimination was 3 consecutive sessions with more than 15 correct choices (P<0.05, Chi-square test). In the red vs. gray discrimination test, the dogs respectively took 3 and 12 sessions to reach the criterion. In the blue vs. gray and green vs. gray tests, both dogs were able to attain the criterion by the 13th session. The results of this study suggest that the color vision of dogs is relatively developed and dogs are able to discriminate between all three primary colors and gray.

In general pig management, suckling period is very important. Mortality with problems such as crushing and diarrhea is higher in the suckling period than in other stages. Wild boars also require much care in this stage. In the present research, observations were carried out on Japanese wild boars under captive conditions in order to clarify the mother-infant behavior during the first week after farrowing. Four females and their litters (4, 5, 6 and 7 boarlets respectively) were observed. Each family was housed in a farrowing pen and videotaped by time lapse recorder. The behavior and location of mother and her boarlets on 1st, 3rd, 5th and 7th days after farrowing were recorded by scan sampling method at 1 min intervals from 05:00 to 18:00. In mothers, the proportion of resting reduced from 55% on day 1 to 39% on day 7 (P<0.05). The ratio of nursing on day 1 was more than that of other days, while the ratio of exploration and walking on day 1 was less than that in other days. The time spent in care-giving was almost the same during this period. The time spent in feeding increased step by step (P<0.05). Boarlets became more active with age. Especially, the proportion of exploration, drinking and play behaviors increased significantly (P<0.05). The total time spent resting of boarlets decreased gradually, but it occupied more than 60% even on day 7. When boarlets were in the nursing box, their mothers rested with her nose into the entrance of the box.

In recent years, the number of wild boar farms has been increasing gradually in Japan. However, behavioral studies on Japanese wild boars have been very few, and behavioral patterns of them have not been clarified scientifically. In this study, behaviors and use of space by Japanese wild boars after weaning were observed to consider the way of management of wild boars. Ten boarlets from three litters were housed in a farrowing pen (5.4m x 1.8m) for 3 months just after weaning. Then they were moved to the rearing pen (10m x 10m). Research 1 : The wild boars were videotaped on 1st, 2nd, 3rd, 5th, 7th , 15th, 25th, 35th, 50th, and 90th day after weaning at the farrowing pen and 1st, 2nd, 3rd, 5th, 7th , 15th, and 25th day after moving to the rearing pen. Active behavior and use of space of them were recorded. Active behavior showed 2 peaks around feeding time. In the farrowing pen, the highest percentage of activity was seen on the first day (76% day time, 46% night time). After grouping, use of nursing box decreased with the passage of day. The percentage on use of farrowing section (around the nursing box) increased after 3rd day. Wild boars used playground near the nursing box more than that near a service passage. In the rearing pen, wild boars often utilized the comer with the door just after moving from the farrowing pen. They used the section under the roof more frequently on rainy day. Re-search 2 : Behaviors and use of the space by the wild boars were observed I year after the research 1 . Diurnal pattern was similar to that of research 1 . Resting showed the highest percentage followed by the order of exploration, walking, standing, feeding, nuzzling and drinking. In this stage, agonistic behavior was observed around the feeding time. The wild boars used the sections near the door more frequently than center of the rearing pen, however there was a difference in the pattern of use of space according to time. Jpn. J. Livest. Management, 35(1) : 7-17,1999 Received August 31,1998 Accepted April 16,1999

The objective of the present study was to determine the visual acuity of pigs under low light intensity. Two female pigs, which had been trained to discriminate between a Landolt ring and an ordinary ring of equal size associated with feed, were used. The best visual acuity scores for the two pigs under adequate light conditions (500 lux) were 0.07 and 0.034,respectively. After the pigs were tested under normal light conditions, their visual acuity was determined by reducing the light intensity to 200,100 and 20 lux, respectively. The pigs were subjected daily to 1 or 2 sessions which consisted of 30 trials each. The criterion of successful discrimination was 3 consecutive sessions with more than 21 correct choices (P<0.05,Chi-square test). The best visual acuity scores for the two pigs under 200,100 and 20 lux were 0.06,0.06 and 0.04,and 0.024,0.024 and 0.02,respectively.Jpn. J. Livest. Management, 34(2) : 57-60,1998 Received February 5,1998. Accepted August 6,1998.

Dominance order and its formation of wild boars at feeding time were studied. Two breeding groups (group A : 1 male and 5 females, group B : 1 male and 6 females) and one raising group (3 castrated males and 7 females) of Japanese wild boars, Sus scrofa leucomystax, in captivity were used in this experiment. Feed for each breeding group was shared by the group members plus one. The position of each feeding spot was determined randomly (spot feeding). The number of movements by wild boars among the feeding spots, the number of animals feeding simultaneously at one spot, and the number of spots which were occupied at the same time were observed. The number of voluntary movements from one spot to another was almost the same among males, alpha females or omega females. Evasive movements due to the approach of others occurred much more among low-ranked females than among high-ranked females (P<0.01), but were not observed among males. The dominance order of wild boars at feeding follows a straight line order, the same as that of domestic pigs. During spot feeding of the raising group, done at one location before this study, the number of voluntary movements was reduced with the passage of time, while evasive movements increased gradually. In breeding groups, wild boars fed at one spot, and no more than 2 animals ever fed simultaneously at one spot. In the raising group, the maximum number of animals feeding simultaneously at one spot was 7 at the beginning of spot feeding, but it decreased to 3 animals 3 weeks later. Evasive movements in the breeding group were caused by the approach of others without hostility. On the other hand, evasive movements in the raising group were mostly caused by contact with others. It is likely that this spot feeding in the raising stage accelerate the formation of dominance order. It has been observed that the dominance order at feeding time coincides with that at other times in breeding groups. Therefore spot feeding is an effective and simple method for ascertaining the dominance order of animals which are hard to tame by man. Jpn. J. Livest. Management, 33(2) : 33-38. 1997. Received April 30,1997. Accepted June 9,1997.

本実験は,無窓分娩豚舎における光周期が雌豚の繁殖成績に及ぼす影響を明らかにすることを目的として,4反復合計で355頭の雑種雌豚を用いて,繁殖成績を比較検討した.分娩豚舎は3区に仕切られ,各区の光周期の設定は,明期(照度20-100lux)を08:30-09:00と16:30-17:00,08:30-16:30,08:30-00:30とし,それぞれ1L区,8L区,16L区とした.供試豚は,交配後109日目に分娩豚舎に移され,離乳まで35日間,各照度の下で飼養された.生産子豚頭数,一腹離乳子豚頭数,一腹離乳子豚体重,および発情再帰率は,いずれの区においても正常な値を示し,区間に有意な差は認められなかった.しかし,離乳時における子豚の平均体重は明期の時間が短いほど重くなる傾向が見られ,1L区と16L区の間の差は有意であった(P<0.01).また,発情再帰日数も,明期の時間が短いほど有意に短くなった(P<0.05).行動観察の結果,8L区および16L区に対し,1L区では哺乳時間が有意に長かった(P<0.05).以上から,光周期が雌豚の繁殖成績に影響を及ぼすことが示された.