Eighty European x American Holstein steers (257 kg L. W.) were used in a 66 days winter feeding trial, to evaluate the effect of treating wheat straw with anhydrous ammonia (NH3), at 0, 1.5, 3.0, and 6.0% by fresh weight, using the "Norwegian" method, at the Quilamapu Exp. Sta. (INIA, Chillán, Chile). The first 3 levels of NH3, were supplemented for weight gains (W.G.) of 0.3 (A), 0.8 (B), and 0.8 (C) kg/steer/day. The 6% NH3 level was supplemented only for 0.8 (C) W.G. (ration with 11.4% more crude protein and 9,7% more TDN than B). These combinations comprised a total of 10 treatments. The design was complete randomized blocks. W.G. were higher (P < 0.05) for steers receiving NH3 treated straw. Highest W.G. (P < 0.05) were obtained with supplement B. The NH3 treatments increased significantly (P < 0.05) crude protein (N x 6.25), in vitro D.M. digestibility, and intake. Hemicelluloses and neutral detergent fibre decreased Iinearly (P < 0.05) with increased NH3 level. There was a trend for a decrease in acid detergent fibre and lignin (non significant) with the increase in NH3 level. Adding urea at feeding time to non treated straw did not produce the same effect as the NH3 treatmento W.G. were lower than expected; protein and energy requeriments must be adjusted when NH3 treated straw is used in a high proportion. NH3 at 1.5% gave satisfactory results, compared to higher concentrations; this would mantain a low straw treatment costo |
ChileanJAR
