This study aimed to determine the effects of feeding limitations in an automatic milk replacer feeding system on calf-starter intake and calf growth. Eleven Holstein male calves were divided into three groups; 1 ) limitation of milk replacer to 3.2 liter (3.2L, n = 4), 2) limitation 4 liter (4 L, n= 4 ), and 3 ) limitation 10 liter (10L, n=3). 1) Total calf-starter intake at 1 to 5 wk of age was higher in the 3.2L group than in 4 L and 10L. 2) At 1 to 3 wk of age, the frequency of access to the automatic milk replacer feeding system of the 3.2L increased to more than the 4L and 10L. However, at 3 to 5 wk of age, the frequency of access to the automatic milk replacer feeding system of the 3.2L group had decreased but the frequency of access for 4L and 10L to automatic calf-starter feeding system increased. 3) At 4 wk and 5 wk of age, body and metabolic body weights of the 10L group tended to be heavier than that of 3.2L. 4) At 5 wk of age, the percentage of calves in each group that took calf-starter of more than 1 kg were 3.2L : 100%, 4 L : 25%, 10L : 0 %. The Japanese Feeding Standard for Dairy Cattle (1999) notes that the weaning yardstick is a calf-starter intake of more than 1 kg. 5) In respect to nursing costs, the 10L group was higher than the 3.2L. These results suggested that the 10L limitation was good to obtain heavy body weights; however, from the viewpoint of nursing cost, the 3.2L limitation for early weaning was more economical.

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In this study we observed the influences of video images and slides of feeding or standing conspecifics and pecking sounds as social stimuli on feeding behavior of 16 adult hens. Each stimulus was presented individually in the way of "continuous presentation" or "connective presentation" . In the continuous presentation six different visual and auditory stimuli were used : moving and static life-size images of both of feeding and standing hens, pecking sounds and a blank illumination (control), with each bird exposed to each of six stimuli for 5 minutes. Both amount of food consumed and number of food pecks were significantly greater when exposed to the moving image of feeding hen than when exposed to others. Following the moving feeding hen's image, static feeding hen's image induced significantly greater food consumption and food pecks than three other stimuli. There was no significant difference between static feeding hen's image and pecking sounds in these two measurements. In the connective presentation experiment, four kinds of stimuli that took turns successively at 15-second shifts with five repetitions during 5 minutes were connected in the same order but different starting point, and consequently four types of presentations were made up in both the moving image - peck sound series and static image-peck sound series. What kind of stimulus appeared first strongly affected food consumption over whole 5 minute period in both series. But time series analysis revealed that change patterns of number of food pecks fluctuated showing the same effects of each stimulus as those found in the continuous presentation experiment and were significantly regular regardless of what kind of stimulus appeared first. It was concluded that feeding behavior of hen could be most strongly accelerated by the visual stimuli of actions of feeding conspecifics and static feeding hen's image might also have a comparable effect to food pecking sounds, and hens could change their feeding behavior at short intervals in keen response to changes of stimuli.

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In attempts to obtain the basic information on the establishment of rice-duck farming system suitable for rice production in Southern Shan State, the Union of Myanmar, the present study was carried out to examine the influence of free-ranging adult Aigamo ducks on the emergence of weeds, pest insect infestations and rice production in the paddy fields. The experimental rain-fed paddy fields (65a) consisted of control plot (0.1a : no fertilizer), conventional plot (55a : chemical fertilizers and hand weeding) and duck plot (10a). Eleven Aigamo ducks at 12 months of age. were free-ranged in the duck plot for 30 days (April 17 to May 16, 2000). The results were obtained as follows : 1 ) There were a lot of water plants, especially Myriophyllum tubereulatum Roxb. and Ceratophyllum demersum L. in the paddy fields. At the end of free-ranging period, the emergence of water plants in the duck plot was significantly less than that in the control plot (P<0.05), suggesting that the Aigamo ducks had higher ability in weed control. 2 ) The infestation of pest insects such as White-backed planthopper (Sogatella furcifera Horvath) and Green rice leafhopper (Nephotettix cincticeps Uhler) was small, so that the effect of pest control was not evident. 3 ) At the end of free-ranging period, the number of tillers per a hill of rice plants in the duck plot was significantly more than that in the control plot (P< 0.05), though there was no significant difference in the length of rice plants between treatments. 4 ) There were few rice plants damaged heavily in the duck plot (less than 0.1% of total). 5 ) The yield of paddy rice in the duck plot was higher than those of control and conventional plots by 132% and 13% respectively. 6 ) No free-ranged Aigamo ducks were dead in this study. 7 ) The duck plot showed its profitability both in terms of the high yields and the income raised by the sales of duck eggs, compared to the conventional plot. These findings indicate that free-ranging of adult Aigamo ducks in paddy cultivation is one of sustainable agricultural production system in Myanmar.

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