Abstract #278

# 278
Forage yield, quality, and digestibility when intercropping vining soybean with MasterGraze seed corn at different seeding rates.
Ishwary Acharya*1, David Casper1, Xingyou Gu2, Ahamed Charif2, 1Dairy Science Department, South Dakota State University, Brookings, SD, 2Department of Plant Science, South Dakota State University, Brookings, SD.

The production of forage resulting from the intercropping of corn and soybean at planting has the potential to yield greater quantities of digestible nutrients to meet the nutrient requirements of lactating dairy cows. A field plot experiment was conducted to measure forage yield, nutrient concentration and digestibility when intercropping MasterGraze (MG) seed corn and vining (V) soybean lines at different seeding rates. A randomized complete block design with 5 different seeding rates [100:0 (T1); 67:33 (T2); 50:50 (T3); 33:67 (T4), and 0:100 (T5) of V and MG] with 3 replicates was used to determine the optimal intercropping seeding rates. Forage was hand harvested 97 d after planting during the 2014 growing season, inoculated, packed into plastic buckets, weighed, and ensiled for 60 or 90 d. Buckets were then re-weighed, opened, and samples of forage collected. Fresh, 60- and 90-d ensiled forage samples were submitted to a commercial laboratory (Analab Inc., Fulton, IL). Fresh forage yield was greatest (P < 0.05) for T5 (all MG) compared with other ratios of MG and V (40.7, 78.0, 75.6, 75.5 and 80.9 T/ha for T1, T2, T3, T4, and T5, respectively). Fresh DM yield (16.5, 22.0, 21.1, 20.2, and 18.7 T/ha) and digestible DM (12.3, 15.2, 14.7, 14.1 and 13.9 T/ha) were similar (P > 0.05) across all V:MG ratios. Fresh CP yield (3.74, 2.29, 2.14, 1.97, and 1.18 T/ha) was greatest (P < 0.05) for T1 compared with other treatments and T2 greater (P < 0.05) than T5 with remaining ratios being intermediate and similar. Fresh digestible fiber yield was similar (P > 0.10) for all V:MG ratios (3.78, 5.55, 6.02 5.22, and 6.45 T/ha). The 60 d DM ensiling loss (5.23, 1.34, 1.22, 1.71 and 1.97%) was greatest (P < 0.05) for T1 compared with the other V:MG ratios. The 60 d ensiling digestible DM yield (12.3, 15.6, 14.9, 14.0 and 12.9 T/ha) was greatest (P < 0.05) for T2 and lowest for T1 with other ratios being intermediate. In conclusion, the intercropping of V and MG holds great potential for increasing the production of forages to meet the nutrient requirements of lactating dairy cows.

Key Words: corn, soybean, yield