Effects of stage of maturity on ensiling characteristics and ruminal nutrient degradability of oat silage

A study was conducted to determine the effects of stage of maturity on ensiling characteristics and ruminal nutrient degradability of oat silage. Oat was field grown and forage was harvested at the boot or soft dough stage and ensiled in mini-silos for 0, 2, 4, 8, 16 and 45 days. Two lactating Holstein cows fitted with ruminal fistulas were used determine ruminal nutrient degradability. Regardless of the stage of maturity, ensiled forages went through a rapid fermentation with a sharp decline in pH during the first 2 days of ensiling. Extensive proteolysis took place between 0 and 2 days as indicated by a reduction in true protein and neutral detergent insoluble protein (NDICP) and an increase in non-protein nitrogen (NPN). Chemical analysis of the 45 days silage showed that stage of maturity had no effect on neutral detergent fibre (NDF) and acid detergent fibre (ADF) of oat silage. However, oat harvested at the boot stage contained more crude protein (CP) and less starch than that harvested at the soft dough stage. Distribution of protein fractions showed that oat harvested at the boot stage contained lower NPN, NDICP and acid detergent insoluble protein than oat harvested at the soft dough stage. Results of the in situ incubation experiment indicated that oat harvested at the soft dough stage had lower ruminal dry matter (60.6 vs. 66.4%), CP (81.3 vs. 88.7%) and NDF (35.4 vs. 42.2%) degradabilities than oat harvested at the boot stage. It was concluded that chemical composition and ruminal nutrient degradability of oat silage are significantly influenced by stage of maturity.