Milk production and urinary nitrogen excretion of dairy cows grazing perennial ryegrass-white clover and pure plantain pastures

摘要

Milk production and urinary nitrogen (N) concentration were measured in late lactation dairy cows grazing a perennial rye-grass-white clover pasture, pure plantain and an area that is comprised of 50% perennial ryegrass-white clover and 50% pure plantainby ground area (50-50 pasture-plantain), (n=12). Milksolids production was greater (P=0.01) for cows grazing plantain (1.67 kg MS/cow/d) than those grazing pasture (1.50 kg MS/cow/d), with cows grazing 50-50 pasture-plantain intermediate (1.60 kg MS/cow/d). Urine-N concentration was 56% lower (P<0.001) for plantain (2.4 g N/L) and 33% lower for 50-50 pasture-plantain (3.6 g N/L) than pasture (5.4 g N/L). Plantain may offer environmental benefits to dairy systems by reducing the urinary N concentrationdeposited on the soil from grazing cows in late lactation.