EFFECT OF NITROGEN FERTILIZATION AND PLANT POPULATION ON THE VALUE OF CORN SILAGE FED TO BEEF STEERS

Abstract

Corn was grown at 86 000 plants/ha and at 129 000 plants/ha and fertilized with nitrogen at rates of 150 and 200 kg/ha in order to determine the effect of population and N-fertilization on field production, silage preservation and animal performance. Silages from the four field treatments were offered ad libitum to Hereford steers during 112 days. Within each of the corn treatments, half of the animals were supplemented with 450 g of soybean meal (48% protein). Under field conditions characteristic of this trial, the higher plant populations and higher nitrogen levels failed to increase corn silage yields and resulted in lower ear production, later maturing plants and a higher plant moisture content at harvest. The trends were most noticeable in the high plant population treatments. The quality of the silage was not affected by the different treatments. No significant differences for total N, soluble N, NH3-N, lactic acid and acetic acid were noted among silages. Animal intake was increased with silages produced on high N-fertilization at 86 000 and 129 000 plants/ha. No significant differences in animal gain or feed efficiency were observed due to field treatments. The addition of soybean meal to the silages diluted the influence of field treatment on animal intake. However, within field treatments the supplement significantly improved dry matter intake, gain and feed efficiency. This study showed no advantage in increasing corn population over 86 000 plants/ha or N fertilization above 150 kg/ha. Key words: Corn silage, plant population, N-fertilization, steers