Use of Milk Lactose Concentration as an Indicator of Mastitis Following the Validation of a Novel In-Line Milk Analysis System Designed to Measure Milk Components

Mastitis, an inflammation of the mammary gland, continues to be the largest source of economic loss for the dairy industry. Often caused by a bacterial infection, this disease causes an increase in the milk somatic cell count (SCC) (Park et al., 2007). The milk SCC, an indication of intramammary infection (IMI), is typically measured by the Dairy Herd Improvement Association (DHIA) laboratory (Lukas et al., 2005). Many farms measure individual cow SCC values once a month and, therefore, cannot be used as the only method of identifying mastitis. The capability to measure not only SCC, but milk components on a daily basis could allow for early identification of disease with minimal labor input. Normal levels of each milk component have been determined for healthy animals. It has been reported that milk lactose concentrations decrease and SCC increases during clinical mastitis (Pyorala, 2003). Unfortunately, the timing relative to onset of clinical signs has not been evaluated. Furthermore, when they were used together results were slightly better than SCC alone. A new in-line milk analysis system (AfiLab) has recently been developed (AfiMilk, Israel). This system was previously evaluated and validated using a Holstein population. However, accuracy of the system was not tested for other breeds. This system measures milk fat, protein, and lactose concentrations as well as SCC at every milking. Due to bacterial utilization, we hypothesize milk lactose concentrations may decrease prior to the onset of clinical signs. Therefore, the objectives of this study were to first evaluate the accuracy and precision of the AfiLab system not only for Holsteins, but also for Jerseys and Crossbreds and to assess the drop in milk lactose concentration around clinical mastitis.