2013 Volume 84 Issue 4 Pages 475-486
A linear programming (LP) model was used to evaluate integration between animal and crop production systems at national level. In particular, this evaluation focused on the utilization of paddy rice field. Animal categories considered were production systems for Holstein cows (milking and dry cows and replacement heifers), Holstein growing calves, dairy fattening steers, Japanese Black cow-calves, Japanese Black fattening steers, fattening F1 steers and heifers, integrated pigs, layers and broilers, and crop categories were feed production for pasture, whole crop rice silage (WCS), feed rice for animals and food rice for human. In addition, external concentrates and roughages were considered. The objective function of the model maximizes total benefits from animal and crop production, while restricting environmental impacts (surplus nitrogen, greenhouse gas emissions, and energy use) and total labor time at national level. The result of optimization for the basic situation suggested that the total benefit may be maximized when the number of Japanese Black and layer increased and the number of other animals decreased and when forage rice for WCS was cultivated instead of food rice. The effects of alternative scenarios such as targeted reduction of surplus nitrogen and green house gas, the amount of subsidies of feed rice in paddy fields, concentrate costs and different processing costs for each animal category in feed rice production on optimization of integration between animal and crop production were also examined.
