Effect of Form of Nitrogen Fertilizer, a Preservative, and a Supplement on the Value of High-Moisture Grass Silage

Experiments were conducted with steers and sheep to determine the feeding value of unwilted grass silage as influenced by fertilizing with different forms of nitrogen, adding a preservative, and feeding concentrates.Nitrogen (168 kg per hectare) applied either as urea or calcium nitrate produced similar levels of total nitrogen in the forage. However, calcium nitrate resulted in higher non-protein nitrogen concentrations, due to higher nitrate, and lower total available carbohydrate content than did urea. The two forms of nitrogen fertilization resulted in silages of similar chemical quality and the performance of steers and nitrogen balance of sheep fed comparable silages did not differ significantly.Steers fed the silages containing an added preservative (75 kg of ground barley per metric ton of forage) gained 0.94 kg per day compared with 0.60 kg per day for those fed the control silages as the only feed. Feeding 908 g per day of a 37% crude protein concentrate did not significantly alter gains of steers fed the ground-barley-preserved silages but increased gains of those fed the control silage by 0.27 kg per day.The addition of 200 g per day of soybean oilmeal to the ration of sheep fed the control silages consistently increased nitrogen retention, but the addition of 200 g of corn starch did not. The use of ground barley as a preservative raised the digestibility of the silage dry matter but did not increase the nitrogen retention of the sheep.