Efeito das taxas de descarte sobre medidas econ？micas de vacas leiteiras em Kentucky

the aims of this research were to evaluate the effect of culling reasons on lifetime economic measures of dairy cows especially, lifetime net income (lni), lifetime efficiency (le), income over feed costs (iofc) and lifetime income per day of productive life (lipl) using 19,565 lifetime records from holstein cows. culling rate was calculated dividing the number of culled animals, yearly, by the number of all animals present in each year. data on reasons for disposal were used to calculate the culling rate distribution, dividing the number of animals in each class of culling reason by the total number of animals. the estimated culling rate was 31.39%. this value was high and could be a result from the short productive life of cows, 25.57 months. the main reasons for disposal were reproductive problems (21.57%), injuries and other causes (21.17%), and low production (17.20%). involuntary culling was responsible for the majority of culling, representing 75% of total. all traits were significantly affected by culling reason. cows culled for dairy purposes were more profitable to producers.