Invited Review: Culling: Nomenclature, Definitions, and Recommendations.

Standardization of terminology is important as people often develop definitions which  the meaning thereof is not recognized or understood by others, or they use one term for different activities or functions. One such term is culling which is used in different ways leading to confusion or misinterpretation. To address this Dr J. Fetrow and colleagues were commissioned by the American Dairy Science Association to address the confusion and come up with recommendations. Their report was published in the Journal of Dairy Science, Volume 89 of 2006, page 1896 to 1905, with the title: Invited Review: Culling: Nomenclature, Definitions, and Recommendations. The Abstract of their report reads: 

Replacing cows on a dairy is a major cost of operation. There is a need for the industry to adopt a more standardized approach to reporting the rate at which cows exit from the dairy, and to reporting the reasons why cows are replaced and their destination as they exit

the dairy. Herd turnover rate is recommended as the preferred term for characterizing the cows exiting a dairy, in preference to herd replacement rate, culling rate, or per cent exiting, all of which have served as synonyms. Herd turnover rate should be calculated as the number of cows that exit in a defined period divided by the animal time at risk for the population being characterized. The terms voluntary and involuntary culling suffer from problems of definition and their use should be discouraged. Destination should be recorded for all cows that exit the dairy and opportunities to record one or more reasons for exiting should be provided by management systems. Comparing reported reasons between dairies requires considerable caution because of differences in case definitions and recording methods. Relying upon culling records to monitor disease has been and will always be an ineffective management strategy. Dairies are encouraged to record and monitor disease events and reproductive performance and use this information as the basis for management efforts aimed at reducing the need to replace cows.