We have investigated ways of measuring captive animals' demands for resources in their environment in order to assess their welfare. In these experiments, the animals have to make an effort to earn a reward (resource), and we quantify their reaction when it is harder to get a reward. Operant conditioning has been used as the method of providing animals with a means of earning a reward, and a second reinforcer has been used as the reward in some cases. However, it is important to pay attention to some factors involved in this method. How to give animals a means of earning a reward and how long they can maintain contact with a reward have an influence on their responses. Moreover, animals' demands for the reward depend on whether or not they can get the reward outside an experimental condition. There are four ways to quantify animal's demand (elasticity of demand, consumer surplus, maximum price paid, and total expenditure), and, if possible, it is recommended that these should be used together. In assessing animal welfare, it is important to correctly set up the experimental conditions.

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The aim of this study were to evaluate the environmental impacts of manure utilization system at Biogas plant compared to Composting system (composting depot) and Separating system (solid composting at depot and liquid composting at slurry store), using the life cycle assessment method. The functional unit was defined as annual manure utilization from 100 dairy cows. The processes of each system associated with manure treatment equipments construction, manure treatment and manure application, and these processes were included in system boundary. Especially, manure application processes were set manure spreader for compost, slurry spreader with splash plate (SP) for liquid compost, slurry tanker with splash plate, band spread (BS) and slurry injection (SI) for digested slurry. The environmental impact categories to evaluate were defined as global warming potential (GWP) and acidification potential (AP). As the results, the GWP were estimated 346t-CO_2eq at Composting system, 625t-CO_2eq at Separating system and 86-90t-CO_2eq at Biogas plant. It showed that the Biogas plant was relatively low GWP for manure utilization system regardless of types of application. The AP were estimated 10t-SO_2eq at Composting system, 18t-SO_2eq at the Separating system, 13-24t-SO_2eq at Biogas plant, and the item which gave the largest impact was NH_3 (98-99%) at all systems. Especially, the large part of NH_3 emission from the Biogas plant was caused at manure (digested slurry) utilization process. However, it was showed that the AP impact was decreasing at the cases of digested slurry application with BS or SI compared with the case of using SP. These results led to the conclusion that the Biogas plant prevents global warming gas emissions, and the digested slurry application with BS or SI was a necessary condition for decreasing AP impact (NH_3 emission) at the Biogas plant utilization.

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To evaluate skin surface temperature measured by a two dimensional radiant thermometer as an indicator of heat stress, a total of 347 surface temperature measurements on the udder and belly were made in Hokkaido and Taiwan dairy herds. The air temperature and temperature-humidity index (THI) in the barns ranged between 9.2 to 32.7 ℃ and 53.6 to 83.5, respectively. The highest surface temperatures on the udder and belly increased with increasing air temperature in the barns (p<0.01). However, in barn temperatures below 25 ℃, the variation of the highest surface temperature on the udder and belly of individual cows at the same barn temperature was relatively greater than when the barn temperature was above 25 ℃, and the variance between above and below 25 ℃ was significantly different (p<0.01). Similarly, the average values, the individual variations, and the variances of the highest surface temperature were different between THI values above and below 70. These results suggested that most lactating dairy cows in the environment above 25 ℃ or 70 THI have to make an effort to accelerate heat emission from their surface, and are considered to be suffering from mild heat stress in the environment above 25 ℃ or 70 THI.

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