Feeding and Managing Dairy Cows in Three versus One Production Group

Abstract

Abstract Lactating Guernsey and Holstein cows were assigned randomly to either a statified here with high, medium, and low production groups or a one-group control herd. Complete rations were formulated to meet National Research Council requirements for average milk production of the group (medium and low) or group average plus 10% (high and control). Cows in the stratified herd were regrouped at monthly intervals. Mean body weights and average daily intakes of hay, silage, and concentrate over 3 yr were similar between treatments. Stratified and control herds did not differ significantly in milk production adjusted for age and season, fat, or reproductive performance. Stratified Guernsey in first lactation produced more milk and required fewer services per conception than controls. Lactation persistency of cows in the stratified herd was unaffected by intergroup transfer. Stratified cows had higher mean monthly Wisconsin Mastitis Test scores.