Effects of nitrogen and phosphorus fertilizers on nutritive value of safflower forage and silage

This experiment was conducted to determine the effects of nitrogen and phosphorus fertilizers on nutritive value of safflower forage and silage by in situ and in vitro methods. The safflower forage was harvested at flowering stage, chopped to 3-5 cm particles and then ensiled in the laboratory silos for 60 days. The experimental treatments included: 1. Unfertilized forage (control), 2. Phosphorus fertilized forage (100 kg per ha), 3. Nitrogen fertilized forage (300 kg per ha), and 4. Nitrogen and phosphorus fertilized forage (300 kg N and 100 kg P per ha). The effect of Nitrogen and phosphorus fertilizers on reduction of Dry mater, Neutral detergent fiber and Acid detergent fiber and increasing of ash, Calcium and Phosphorus of forage and silage was significant. The Nitrogen fertilizer significantly increased Crude protein, Non-protein nitrogen and Buffer soluble protein and decreased the Acid detergent insoluble nitrogen content of silage. The Nitrogen and phosphorus fertilizers caused the significant increase of the degradability of both safflower forage and silage. The highest production of gas after 96 h of incubation belonged to treatment 4 and the lowest was for treatment 1 (for both forage and silage). The effect of Nitrogen and phosphorus fertilizers on gas production of forage and silage was significant. Applying the Nitrogen and phosphorus fertilizers caused the significant increase of the gas production parameters including b and c fractions and also Metabolism energy content of forage and silage. Nitrogen and phosphorus fertilizers application caused the production of the higher quality forage for making silage and also improving the Dry mater digestibility of silage.