Age and weight at first calving and subsequent performance in Dutch dairy cattle from rearing farms.

Calf-cow records from 1081 replacement heifers raised on 42 specialised rearing farms in the province of Noord-Brabant have been analysed. The predominant breed was Meuse-Rhine-Yssel (MRY). The objective was to study the relationship between weight and age at first calving and milk production in subsequent lactations, herd life span, dystocia and first calving interval.

[Results obtained using an attenuated bovine syncytial virus vaccine against bronchopneumonia of yearlings (author's transl)].

Bronchopneumonia of yearlings is a respiratory infection with bovine respiratory syncytial virus (BRS virus) occurring as a herd disease in young cattle. In severe cases, the clinical picture is identifiable; characteristic features are laboured respiration and a high morbidity rate. Following an acute onset, atypical interstitial pneumonia is observed on postmorten examination and bacteriological studies are negative.