This paper presents 3D model generation of cattle by shape-from-silhouette method for ICT agriculture. The use of advanced ICT has any possibility to improve various agricultural activities. The authors have such a project whose targets are beef cattle. The goal of the project is to capture 3D shape information of cattle for the estimation of their body condition scores (BCS). Cattle do not stop moving because they are animals. Therefore, it is very difficult to capture their body shape information even using a commercial 3D scanner. Another reason is that the color of beef cattle is almost black and then a commercial 3D scanner like a laser range finder cannot be used. The authors use multiple RGB cameras to capture silhouette images of a cow and employ shape-from-silhouette method to generate its 3D model. Actually, the authors have taken multiple RGB camera images of cows and generated their 3D models. And then, it can be found that the generated 3D models' volumes of cows have positive correlation with their weights. This result says that the estimation of cows' weights is possible from multiple RGB camera images of them.