413 The Effect of Harvest Method and Ammoniation of Corn Residue on Growing Calf Performance.

© The Board Regents of the University of Nebraska. All rights reserved. spreader is disengaged, dropping the tailings in a windrow. The chemical treatment factor entailed feeding residue from each harvest method either untreated or with ammoniation (CONVAM, 2RAM, EZBAM). Diets consisted of 65% corn residue (type varied by treatment), 30% wet distillers grain, and 5% formulated supplement which contained trace minerals, limestone, Rumensin and Soypass (Table 1). Overall, this resulted in six different treatment diets being fed, with 20 steers per treatment. The 84day trial was conducted at ENREC, in Mead, NE, at the individual feeding barn equipped with a Calan Gate® system. Feed was delivered between 7:00 am and 9:00 am, and was offered at approximately 110% of ad libitum intake. Orts were collected daily, composited on a weekly basis and subsampled, dried in a 140 ̊F forcedair oven to determine dry matter, and retained for analysis. Diet ingredients and whole diet samples were also collected weekly throughout the study to assess nutrient content. Corn residue was harvested at the ENREC on two adjacent fields in November 2016 using conventional harvest with rakeandbale (Vermeer VR1428 High Capacity rake), New Holland CornrowerTM with only two rows of stem being added to the windrow, and the EZ Bale system where the combine spreader is disengaged and the tailings are baled. After baling, 65 bales (19 2ROW, 25 CONV, 21 EZB) were separated and stacked on a concrete pad lined with black plastic. Bales were stacked randomly (2Row) resulted in a 15% increase in DM digestibility and a 46% increase in NDF digestibility compared to conventionally harvested corn residue (2017 Nebraska Beef Cattle Report, pp. 62– 63). In that same study, ammoniation of residue regardless of harvest method increased NDF digestibility 21– 37%. Ammoniation is a temperaturedependent chemical reaction where the rate of reaction increases with temperature, and it is unclear if residue can be successfully treated immediately after harvest in the late fall when ambient temperatures are low. It is also unknown how much the improvements in digestibility previously observed would affect the performance of growing cattle. Therefore, the objective of this study was to assess growing cattle intake, gain, and feed conversion when fed diets consisting of corn residue harvested with three different methods that was either nonammoniated or ammoniated in the late fall.