Challenging the norm – cull rates and farm economics

Culling has often been seen as removal of cows from the herd that were either too broken or did not pay for their feed cost anymore. This norm on cull rates may be challenged in several different ways. First, cow replacement rates are primarily the result of how many heifers have been raised to enter the herd. In closed herds, this decision starts at breeding with the as­signment of semen types (sexed or conventional, dairy or beef) some 33 months before the heifer calves. Second, continuous improvements in health, fertility and milk production through management and genetics remain important. This makes for more profitable cows that can stay in herds longer. However, if there is sufficient variation among cows, it will remain a good decision to replace the least profitable cows sooner rather than later. A longer productive life (lower replacement rate) is there­fore not necessarily better. Third, there is still quite a bit of work to be done to better support the most profitable replace­ment decisions. Better replacement decisions, in turn, will drive how many heifers are needed and therefore what the opti­mal cull rate will be.