Effects of Maturing Stage of Corn Hybrids on Silage Yield, Feeding Value for Dairy Cows and Milk Production in a Cold Region of Japan

This experiment was conducted to evaluate the effects of differently maturing corn hybrids on silage production and milk production per unit area in the northern part of Japan, where grain development occurs under decreasing ambient temperature. Both hybrids were harvested at the same time. The stages of maturity for the early-maturing hybrids (EH; 80 d relative maturity) and the mid-maturing hybrids (MH; 93 d relative day) were early dent and late dough stage, respectively. The plant yields for MH were higher than those for EH. The dry matter (DM) content of MH was lower than that for EH, and the effluent loss for MH silage was greater than that for EH silage. Therefore, the DM yields of prepared silage per area were similar for both treatments. Twelve multiparous mid-lactation Holstein cows ($58{\pm}13$ days in milk) were fed diets based on EH or MH silage in a crossover design with two 3-week periods. Cows were fed 3 kg of hay crop silage (DM basis) and either EH or MH silage ad libitum, and concentrates were supplied to meet NRC requirement for dairy cows. Silage DM intake for EH was found to be higher (p<0.05) than that for MH (10.0 vs. 9.1 kg/day). Milk production and milk composition for EH were similar to those for MH. Feed efficiency per total feed intake was similar in both treatments, although the feed efficiency per concentrate intake tended to be higher for the EH than that for the MH diet. These results indicate that differences in maturation in corn hybrids affect the effluent production of silage and the silage intake of dairy cows. It may be advantageous to plant early hybrid corn with a reduction in effluent production of silage as well as a reduction in purchased feed costs for dairy cows under the climatic conditions of the northern part of Japan.