Effect of nitrogen fertilization on the forage production, crude protein content and stocking rate of ryegrass pastures

Abstract

The objective of this study was to evaluate the forage production and crude protein content of three ryegrass stands (Lolium multiflorum Lam. cv. Comum) fertilized with 50, 100 and 150 kg N/ha in the form of urea from May to October 2012. Five grazing cycles were conducted. Holstein cows (530 kg body weight) supplemented daily with 4.5 kg concentrate were used for the evaluation of ryegrass pasture. Pre- and post-grazing forage mass, the botanical and structural composition of ryegrass, and stocking rate were evaluated. Forage samples were collected by the pasture simulation method for the analysis of crude protein. A completely randomized experimental design consisting of three treatments (N levels) and three repetitions (paddocks) was used. The mean forage production, crude protein content and stocking rate were 4827, 6344 and 6123 kg/ha; 20.17, 21.51 and 22.82%, and 2.3, 2.95 and 3.32 AU/ha for the treatments with 50, 100 and 150 kg N/ha, respectively. The maximum nitrogen level recommended is 100 kg N/ha.

Keywords

• Lolium multiflorum
• lotação rotacionada
• vacas em lactação