Abstract
Improve the growth of livestock (calves) in winter, we developed a hybrid hot water supply system connecting a solar water heater and oil heating, and verified economic effects of hot water supply to calves. Water warming in the solar water heater during the study period was 0.9-37.2 °C (average 21.7 °C). Water which supplied to the livestock drinking water tank from the solar water heater via the heat source for oil heating exceeded 35°C on some days. After that, the water temperature decreased with the passage of time due to heat dissipation. Comparing the market of calves at Kawajiri Farm (Shimonoseki City, Yamaguchi Prefecture), which is a demonstration farm, after the introduction of the hot water supply system, the weight of calves increased compared to before, and the daily gain was over 1.0 kg/head, and the profitability improvement was about 42 000 yen/head (difference in average auction price by each bull). It was suggested that the usefulness of this developed hybrid hot water supply system.
