Why is longevity an important metric for the modern dairy herd?

Longevity of a dairy herd can reflect the health and welfare status of the herd and has a role in terms of public perception of the dairy industry. The natural lifespan of a dairy cow has been reported to be approximately 20 years; however, research has highlighted that it is more like 3.6 lactations (approximately 6 years) in the UK and 2.8 lactations (approximately 5 years) in the USA. This indicates that management decisions are having large impacts on the average productive lifespan of dairy cows, with the removal of cows from a herd due to old age being rare. Increasing the longevity of a dairy herd has been promoted as it decreases the requirement for replacement heifers and increases the average herd production level.