The purpose of this study was to estimate the body weights (BWs) of cattle (Bos taurus) under free-posture conditions, with no movement or restraint of the animals. Dairy cows at different life stages were photographed from above in both lying and standing positions. Several body-shape indices were measured based on the captured images, and relationships with BWs were analyzed. From these relationships, we created models to estimate BWs using shape indices based on all of the data for each life stage of multiparous cows and heifers of more/less than 250 kg. In both standing and lying positions, area measurements of the upper portion of the body had the highest correlations with BW. In the model using all of the data, predicted BWs varied most for cattle that were multiparous, and were underestimated for low-BW cattle. In the models of the standing and lying positions created for each life stage, BW was estimated with high accuracy, except in the case of multiparous cattle. No bias was shown between BWs in the standing and lying positions. These results imply that cow BWs can be estimated using photographs of standing and lying cattle.

Due to the soaring prices of imported feed, there is increasing demand in Japan for domestically produced concentrate feed. In response, large machinery made overseas is being used to produce corn grains and ear corn in large areas of Hokkaido and other Japanese prefectures. In prefectures, it is difficult to operate large machinery sufficiently efficiently to reduce expensive machinery costs. Furthermore, because corn grains are harvested at full maturity, in areas west of the Kanto region, typhoons, mold, and weeds are common problems. In response, we developed a snapper head that can be attached to a self-propelled harvesting roll baler, widely used by contractors in prefectures. The developed snapper head targets ear corn, which can be harvested at the yellow maturity stage as a domestic concentrate feed produced in the prefectures. The developed machine is smaller, lighter, and less expensive than those made overseas. The said machine achieved the development targets of a total loss of four percent or less at a harvesting and effective field capacity of 0.3 ha/h or more, and the fermentation quality of ear corn silage was also good. The developed machine is scheduled to be marketed from FY2023.

In 2019, fall armyworm (FAW; Spodoptera frugiperda) initially invaded the Kyushu region of Japan. As FAW is one of the most important pests to maize, this invasion posed a serious threat to forage maize production. However, the impact of FAW on forage maize has not yet been determined. Herein, summer-sown forage maize was cultivated with and without insecticide to evaluate how were the insect damage and yield loss caused by FAW in 2020. In maize cultivated without insecticide, damage to the leaves was noted between the 4-leaf stage and the tasseling stage, and on the ear in the later stages. Consequently, ear dry matter yield, total dry matter yield, and total digestible nutrition yield in the maize untreated with insecticide were 21%, 17%, and 20% lower, respectively, than those of the maize cultivated with insecticide; and thus the economic loss was estimated at approximately 210,000 yen per ha. Summer-sown forage maize is mainly cultivated in the southwestern regions of Japan. While further investigations are needed to clarify the extent of damage caused by FAW, if damage similar to our observation study occurs commonly in maize fields, an optimal pest management to FAW is required to prevent yield and economic losses.