Descriptive epidemiology of calfhood morbidity and mortality in New York holstein herds

Abstract

A prospective cohort study was done of 1171 Holstein heifer calves born from July 1983 to 30 April 1985 and kept to be raised as replacements in 26 commercial dairy herds in the vicinity of Cornell University. The objectives were to examine the interrelationships of management with morbidity and mortality at both the individual and herd level, and the long-term effects of morbidity on survical. The study population, data collection and processing methods, and the descriptive epidemiology (e.g. age and temporal distributions) of calfhood morbidity, mortality and treatments are described. The clinical signs (as diagnosed by farmers on standardized check-off forms) studied were: scours/diarrhea within 14 days of birth and from 15 to 90 days of age; dull, listless, droopy ears, or of feed within 90 days of birth; cough, runny nose or eyes, or trouble breathing within 90 days or birth; death prior to 90 days of age. The crude incidence rates of scours within 14 days of birth, scours from 15 to 90 days of age, dullness, respiratory illness and death were 9.9, 5.2, 7.7, 7.4 and 3.5 per 100, respectively, for the period of study. The only seasonal effect on incidence was for scours within 14 days of birth (which was higher in winter compared to summer across both years of the study). The incidence rates of scours from 15 to 90 days of age, dullness and respiratory illness were higher in the first year of the study compared to the second year; there was no effect of season on these outcomes. The mortality rate within 90 days of birth was not related either to year of study or season. The median ages at occurence of scours within 14 days of birth, scours from 15 to 90 days of age, dullness, respiratory illness, and death were 6, 30, 16, 25 and 28 days, respectively. Risks of clinical signs were highest in the first week of life, while risk of death was highest in the third week. Calves with only scours within 14 days of birth or only scours from 15 to 90 days of age were treated primarily with oral electrolytes, oral antibiotics, and restriction of milk consumption. Calves with only dullness or only respiratory illness were treated primarily with intramuscular antibiotics. The median herd incidence rates of scours within 14 days og birth, scours from 15 to 90 days of age, dullness, respiratory illness and death were 5, 0, 0, 0 and 0 per 100, respectively, during the periof of the study.