Frequency and Effects on Production of Blind Quarters in First Lactation Dairy Cows

Abstract

During 1959 to 1979, 38 of 1177 cattle in first lactation freshened in the University of Florida herd with one or more nonfunctional quarters (48 total quarters). Detailed examination of five quarters diagnosed as blind gave presumptive evidence that blindness was caused by failure to develop duct tissue rather than ductal obliteration from infection. Effects of season and year of parturition and their interactions could not be detected on either the presence of one or more blind quarters or the number of blind quarters. Slight increases in each occurred with advancing age at parturition (.23% and .10 per mo). Breed effects were detected with Holstein and Holstein crossbreds having higher frequencies. Within breed heritability was 0, however. Loss of milk associated with one blind quarter was 558kg (16.2% of overall mean), but most of this loss was from shorter lactations resulting from earlier culling. Adjusted to constant length of record, milk yield loss was 59kg (1.7% of mean). In view of absence of additive genetic variance within breed, management practices needed to reduce frequencies of nonmastitic blindness warrant additional investigation.