A Comparison of the Nutritive Value of Alfalfa Hay with Brome Grass and Reed Canary Grass Hays at Various Levels of Nitrogen Fertilization

Abstract

Brome grass hays grown with 25, 125, and 225 pounds of nitrogen per acre, and reed canary grass hays grown with 0, 100, and 200 pounds of nitrogen per acre, were compared to alfalfa hay in two total collection digestion trials using 4 lambs each, to determine the effect of nitrogen fertilization on the digestibility of the hays. Both total digestible nutrients (TDN) and digestible energy (DE) were determined and compared as to their quantitative relationship. Increasing nitrogen fertilization caused an increase in the protein content from 7.9 to 15.2% in the brome grass hays and from 12.6 to 20.1% in the reed canary grass hays. At the higher levels of nitrogen fertilization on brome grass there was also an increase in the gross energy and ether extract content while the fiber and nitrogen-free extract decreased. No similar trend of the crude components was observed with the reed canary grasses, which may be due to the several variables encountered in the production of these hays. A statistically significant increase of the apparent digestibility of protein with increasing nitrogen fertilization was observed with both grass species. Energy digestion coefficients are also increased at the higher levels of fertilization in the case of brome grass. These differences were less marked and not significant between all levels. The fiber digestion coefficients of all grass hays were considerably higher than those of alfalfa hay. The correlation coefficients between TDN and DE were + 0.95 for the brome grass trial and + 0.87 for the reed canary grass trial and significant at the 1% level of probability. This indicated the close relationship of the two methods of feed evaluation. Regression equations between TDN and DE were Y = 189.82 + 42.87 X for the brome grass trial, and Y = 758.42 + 32.98 X for the reed canary grass trial, where Y is DE in Calories per gram and X is the TDN percentage of the hay.