NONLINEAR MIXED-MODEL ANALYSES OF 5 PRODUCTION DISORDERS OF DAIRY-CATTLE

A standardized threshold model was used to estimate herd variability and the impact of some risk factors on the incidence of retained placenta, metritis, ketosis, ovulatory dysfunction, and mastitis. Data consisted of records for 18,110 Swedish Red and White cows in 924 herds and 14,940 Swedish Friesian cows in 772 herds. Only first, second, and third parity cows were included, and the breeds were analyzed separately. Herds were considered to be random effects, and variance components were estimated by the counterpart of REML for a threshold model. Estimated intraherd correlations varied from .04 to .18 and were lowest for the incidence of retained placenta (for both breeds) and highest for ketosis and ovulatory dysfunction for Swedish Red and White and Swedish Friesian breeds, respectively. Parity increased predicted lactational incidence risks for all disorders except metritis, but season of calving had no profound effect. Dystocia and stillbirth increased the risk of retained placenta; dystocia and retained placenta increased the risk of metritis. The risk of ketosis was not influenced by any of the considered risk factor diseases, and the risk of mastitis was influenced only by retained placenta for Swedish Red and White cows. For both breeds, the risk of ovulatory dysfunction was increased by metritis and ketosis.