ChileanJAR

During the winter season, a 104 day trial was conducted at the "Humán" Experimental Station, Los Angeles, Chile. Wheat straw treated with anhydrous ammonia (3.2% D.M.), using the "stack method" was evaluated. 32 holstein steers (212 kg initially) were used to compare 4 treatments: I. Untreated wheat straw (W) + 0.8 kg concentrate (C) + 72 g urea (U); II. W + 1.6 kg C + 72 g U; III. Ammoniated straw (WNH3) + 0.8·C;and IV. WNH₃ + 1.6 kg C. Liveweight gains of steerswith WNH₃ were larger (P < 0.05) than with W. Also, gains increased significantly with the higher level of concentrate. The ínteraction ammonia treatment-concentrate was not significant. Gains (kg/day) were 0.29, 0.51, 0.52, and 0.79, for treatments I, II, III, and IV, respectively. Intake of straw was 22% higher for steers receiving WNH₃ Increase of crude protein was 5.5 porcentage units for WNH₃. In vitro dry matter digestibility of wheat straw was improved by 22.3% and cell wall digestibility by 24.8%. The use of anhydrous ammonia is a simple method to improve nutritive value of wheat straw and its use will depend on the cost of the treatment, as compared to the price of alternative forages.