Abstract
In this study, we surveyed 290 commercial cow-calf operations in Japan for manganese, iron, cobalt, copper, zinc and molybdenum concentrations in prepartum diet for Japanese Black beef cows. All feed ingredients including roughage, concentrate, commercial compound feed, supplements and salt blocks were collected. Concentrations of the trace elements were measured by ICP mass spectrometry. Then we estimated concentration of each trace element in final diet by calculation from trace element concentration of each ingredient and its daily supply based on the questionnaire to feeders. Almost all the farms gave diet meeting the recommended value of manganese, iron, and cobalt (Japanese Feeding Standard for Beef Cattle 2008). The farms which gave diet with less copper or zinc concentration than the recommended value were 53.4% and 14.1%, respectively. Such diets with low copper or zinc were found more frequently in Hokkaido than in Tohoku and Kyushu-Okinawa areas. Diets with iron concentration above the maximum tolerant level (1,000 mg/kg DM, Japanese Feeding Standard for Beef Cattle 2008) were found in 4.1% of farms. Average calving interval in each farm was obtained from 242 farms. Calving interval was shorter in Hokkaido compared with Tohoku and Kyushu-Okinawa areas. In Kyushu-Okinawa area, shorter calving interval was associated with higher manganese, iron or copper concentration in the diet. In Hokkaido and Tohoku areas, calving interval was not correlated with any element. In summary, copper deficient diet for prepartum beef cow is still found frequently among cow-calf operations in Japan, and shorter calving interval was associated with high manganese, iron or copper in prepartum diet for beef cows in Kyushu-Okinawa area.
