摘要：The National Dairy Heifer Evaluation Project ( NDHEP ) was conducted by the National Animal Health Monitoring System (NAHMS ) from April 1991 through July 1992. A total of 921 producers monitored calves on a daily basis from the first through the eighth week of life; results were extrapolated to the U.S. dairy population. Mortality of heifer calves was examined according to region ( west, midwest, northeast, southeast ). Mortality was highest in the western region ( 9.1 percent ) and lowest in the midwestern region ( 5.6 percent ). Calf deaths were highest in the two quarters October-December and January-March ( 8.4 percent each quarter ) and lowest in the quarter April-June ( 5.2 percent ). The overall average of stillborn calves was 1.6 percent. Calving without assistance was the norm for 68.4 percent of dams giving birth for the first time. This percentage increased through the third birth to 88.6 percent. Of hand-fed calves ( 62.7 percent ), 49.1 percent received 2 or fewer quarts of colostrum at first feeding. Over half of calves ( 51.5 percent ) were separated from dams less than 12 hours after birth. Of calves that died during the study, 26.9 percent of deaths occurred during the first week of life. By the eighth week of life, 27.2 percent of calves had exhibited symptoms of scours at some point, while 8.9 percent had shown signs of respiratory problems. By the fifth week of life, 37.9 percent of calves had received treatment for symptoms of illness, the most common of which were feeding of antibiotics, injection of antibiotics, and feeding of gut soothers ( 29.8, 24.5, and 24.1 percent of calves, respectively ). Cumulatively, 15.1 percent of calves received vaccinations. Contact for this paper: Stephen Ott
