De economische gevolgen van een verlenging van de tussenkalftijd bij hoogproductief melkvee

Abstract

The fertility of high yielding dairy cows has decreased during the last 25 years. For example, the calving-interval (CI) has extended with 30 days (from 390 days in 1992 to 420 days in 2008). Consequently, practitioners dealing with herd health management, are often faced with farmers' questions about the financial impact of an extended CI. Numerous studies have attempted to calculate the economic consequences of an extended CL Some researchers based their investigations on real data and analyzed them retrospectively, while others simulated situations by complex models. Undoubtedly, the lactation curve is the most important contributor to these calculations, besides a whole range of other factors, which may influence the economic results in a positive or negative way. Consequently, conclusions are not always that unambiguous. In general the conclusion is that an extended CI will result in a loss of money. Extending the CI from 395 days to 432 days for instance results in a loss of € 2.08 per cow per day; in total € 77 per cow (37 days). Because the lactation persistency is rather plastic, some managerial measures, such as a higher milking frequency and the use of bovine somatotropin, can be taken to increase the persistency resulting in a less negative or even a positive economic balance.