Alkaline Treated Wheat Straw or Corn Stover Fedto Growing Calves

This experiment utilized 460 steers (initial BW: 729 ± 44 lb). Steers were received during the fall of 2011 and grazed corn stalks from late November until start of the experiment (Feb. 23, 2012). Corn stover was treated using CaO (standard quicklime; Mississippi Lime Company, Kansas City, Mo) and carried out using a patented process with successive tub grinders (Performance Plus Liquids, Inc., Palmer, Neb). Wheat straw was treated with CaO every two weeks similar to as described in previous reports (2012 Nebraska Beef Cattle Report, pp. 106-107; pp. 108-109). In both corn stover and wheat straw treatments, the mixture was calculated to be 50% DM with calcium oxide added at 5% of the total DM. Treated corn stover and treated wheat straw DM averaged 57.6 and 49.6%, respectively. Treated corn stover and wheat straw were stored anaerobically in silage bags throughout the trial. The authors recognize that methodology to apply alkaline treatment is a critical factor to be considered. Correspondingly, since two types of processes were used to treat corn stover and wheat straw, this could potentially influence the response to treatment and results. Steers were limit-fed a mix of 47.5% alfalfa hay, 47.5% wet corn gluten feed, and 5.0% supplement at 2% of BW for five days prior to trial initiation and five days following to equalize gut fill. Steers were weighed two consecutive days following five days of limit-feeding at initiation and at the end of the trial. This trial was designed as 2 x 2 factorial with factors consisting of alkaline treatment (CaO+ H 2 O vs. none) and residue (corn stover vs. wheat straw). There were three initial weight blocks, six replications per treatment, and 19 steers per pen. Diets (Table 1) were offered ad libitum to steers once daily. Treated diets contained sufficient Ca (3.35% from CaO treatment) and supplement was included at 1.0%. Untreated diets had supplement inclusion of 3.0% and limestone was added (1.58% of diet DM) to maintain a Ca:P of 1.2:1. Monensin was included in both supplements and formulated to supply 200 mg/steer daily. Monthly composite samples were assayed for