Ammoniation of wheat straw and native grass hay during baling of large round bales

• Published in: Animal feed science and technology Vol. 8; no. 1; pp. 35 - 46
• Main Authors: Horn, G.W., Batchelder, D.G., Manor, G., Streeter, C.L., McLaughlin, G.L.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1983
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/0377-8401(83)90041-X

Wheat straw and native grass hay were treated with anhydrous ammonia during baling with a large round baler. In Experiment 1, ammonia (3.2 and 7.1% w/w of straw DM) was applied by use of a Cold-flow Converter to wheat straw that either had not been sprayed or had been sprayed with one of two rates of water as it passed over the pick-up frame of the baler. Straw water concentrations immediately after baling were 13.8 and 23.8%, respectively, for the low and high rates of water application. Straw water concentrations were about 12 percentage units lower than anticipated, and indicate that water penetration of the hard cuticular surface of the straw was low. Treatment with 3.2% ammonia of straw not sprayed with water increased the crude protein content from 3.2 to 5.7% immediately after baling. However, none of the ammonia-nitrogen (NH 3-N) was retained 45 days after baling, and dry matter digestibility in vitro (IVDMD) of the straw was not increased. Straw that was treated with low levels of both ammonia and water contained 6.0% crude protein after storage, and IVDMD increased 27% (i.e., 36.7 vs. 28.9%; P < 0.001). Retention of NH 3-N after storage ranged from −1.4 (low level of ammonia and no added water) to 14.8% (low level of both ammonia and water) and was increased ( P < 0.001) by added water at the low level of ammonia application. The effects of crimping wheat straw during baling and addition of a surfactant (0.2% v/v) to aqua-ammonia on crude protein content, retention of NH 3-N and the IVDMD of straw were studied in Experiment 2. Water content of ammoniated straw in Experiment 2 (ca.14%) was similar to that of straw sprayed with the low level of water in Experiment 1. Crimping did not visibly disrupt the surface of the straw, nor affect crude protein content or IVDMD. Addition of surfactant to the aqua-ammonia increased ( P < 0.01) the crude protein content after storage of non-crimped and crimped straw, respectively, by 0.3 and 1.5 percentage units ( P < 0.05 for crimping by surfactant interaction). Straw IVDMD was not increased by either crimping or addition of surfactant to the aqua-ammonia. Retention of NH 3-N after storage, which ranged from 26 to 49%, was greater than that of Experiment 1, and was attributed to the lower level of ammonia application (1.7% of straw DM). Native grass hay readily adsorbed aqua-ammonia. Water content of the hay was increased from 12.2 to 28.7%, and the crude protein content was increased from 4.4 to 13.9% by ammoniation. The studies indicate that while ammoniation of crop residues during the baling operation is a possible means of treatment, low retention of NH 3-N remains a problem. Disruption of the hard cuticular surface of residues such as wheat straw may improve penetration of aqua-ammonia and therefore the effectiveness of treatment.