Influence of Levels of Nitrogen Fertilization and Growth Stage of Plants for Hays and Silages on Digestibility and Nutrient Intake by Cows and Sheep

Abstract

A field of mixed forage, predominantly timothy, was fertilized with 3kg (low) or 12kg (high)/10 a of nitrogen fertilizer and was harvested for hay and silage either on June 18 (early) or July 8 (late). Digestibility was tested in sheep and palatability in Holstein cows. The high fertilization increased digestibility of crude protein and DCP content of hays and silages prepared with early and late harvests (P<.01). It also increased TDN content of late harvests (p<.01) but not of early one. High fertilization resulted in low quality silage with early harvest and very good silage with late harvest. Consumption of hays and silages by the cow, in terms of DM and TDN, decreased in early harvest and increased in the late harvest with increasing usage of the fertilizer. In terms of DCP, food consumption was always proportional to the level of fertilizer used.