Nitrogen Retention and Chemical Composition of Urea Treated Wheat Straw Ensiled with Organic Acids or Fermentable Carbohydrates

The influence of varying levels of urea and additives on nitrogen (N) retention and chemical composition of wheat straw was studied. The wheat straw was treated with 4, 6 and 8% urea and ensiled with 1.5, 2 and 2.5% of acetic or formic acid and 2, 4 and 6% of corn steep liquor (CSL) or acidified molasses for 15 days. The N content of wheat straw was significantly different across all treatments. The N content of urea treated wheat straw was increased with the increasing level of urea. The N content was higher in urea treated wheat straw ensiled with acetic or formic acid as compared to urea treated wheat straw ensiled without these organic acids. The N content of urea treated wheat straw was further enhanced when it was ensiled with CSL or acidified molasses. This effect was significant across all levels of urea used to treat the wheat straw. Nitrogen retention in urea treated wheat straw was decreased linearly as the urea level was increased to treat the wheat straw. The N content was increased linearly when higher levels of CSL or acidified molasses were used to ensile the urea treated wheat straw. Most of the N in urea treated wheat straw was held as neutral detergent insoluble N (NDIN). The NDIN content was increased linearly with the increasing levels of urea and additives. The neutral detergent fiber (NDF) contents were higher in urea treated wheat straw ensiled with acetic or formic acid as compared to urea treated wheat straw ensiled without additive. The NDF content further increased in urea treated wheat straw ensiled with CSL and acidified molasses. The entire increase in NDF content was because of fiber bound N. The hemicellulose content of urea treated wheat straw ensiled with CSL or acidified molasses was higher as compared to urea treated wheat straw ensiled with acetic or formic acid. The acid detergent fiber content of urea treated wheat straw ensiled with or without additives remained statistically non-significant. The cellulose contents of wheat straw was linearly reduced when urea level was increased from 4 to 6 and 8% to treat the wheat straw. This effect was further enhanced when urea treated wheat straw was ensiled with different additives. The results of the present study indicated that fermentable carbohydrates might improve the Nitrogen retention and bring the favorable changes in physiochemical nature of wheat straw. However, biological evaluation of urea treated wheat straw ensiled with fermentable carbohydrates is required.