Dairy Production and Reproduction in Holstein-Friesian and Guzera Crosses

Abstract

Data on 660 first and second lactations and on 506 calving intervals were used to characterize six red and white Holstein-Friesian x Guzera crossbred groups (1/4 to ;81/32 European grade) on 65 fanns stratified into high and low management classes. Milk, fat, and protein yield per lactation and per day of calving interval were analyzed with models including effects of management, farm, and year-season of freshening. Within-class regressions were fitted for direct gene effects and heterosis, or, alternatively, crossbred classification effect and its interaction with management class. The interaction between crossbred group and management class was important for most traits.