Peer review

Three experiments were conducted to compare the feedlot performance of cattle fed corn silage treated with cold-flow anhydrous ammonia (ANAM) with the performance of cattle fed corn silage treated with other forms of nonprotein nitrogen (NPN) at the time of ensiling or untreated silage supplemented with soybean meal (SBM) at feeding time. Various sources and levels of supplemental N and systems of protein and mineral supplementation were evaluated to determine their effect on the feedlot performance of growing and finishing steers. A weighted average across the three trials revealed that cattle fed ANAM-treated silage had a 4.5% lower average daily gain (ADG) and an 8.8% higher dry matter intake/kg of gain than those fed untreated corn silage supplemented with SBM to a similar crude protein equivalent. In trial 1, addition of minerals in the form of ammonia mineral suspension (AMS) at time of ensiling resulted in a higher ADG (P = .004) and lower intake/kg of gain (P = .007) than did addition of minerals to ammonia-treated silage at feeding time. However, in trial 3, addition of minerals or calcium hydroxide to ANAM-treated corn silage at the time of ensiling resulted in no improvement in animal performance. Soybean meal supplementation of silage treated with 7.80 or 10.29 g of ANAM/kg of corn silage dry matter (CSDM) during the initial phase of the feeding period resulted in a higher ADG (P<.0005) and lower DM consumption/kg of gain (P = .052) in trial 2. However, in trial 3, SBM supplementation of silage treated with 7.80 g of ANAM/kg CSDM resulted in no improvement in overall performance (P>.20). In trials 2 and 3, supplementing untreated corn silage with SBM at a percentage of the diet that was decreased as the cattle became heavier resulted in ADG and feed efficiency similar (P>.20) to those obtained from the feeding of a constant level of SBM throughout the feeding period. In trial 3, cattle fed ANAM-treated corn silage had higher marbling scores (P = .030) and higher quality grades (P = .030) than those fed untreated silage supplemented with SBM. Carcass data were not collected in trials 1 and 2.

Text in English