Methods development for detection and prevention of subacute ruminal acidosis in dairy cattle

Modern herd management is suspected to be the main cause of subacute ruminal acidosis (SARA). This metabolic disorder, which is characterized by a drop in ruminal pH below 5.6 for 3 to 5 hours, is associated with a decrease in productivity and feed efficiency of high-producing dairy cows, and therefore has significant consequences on herd health as well as business financials. Despite the fact that SARA is a well documented metabolic disorder, its diagnosis remains problematic, mainly because symptoms associated with this disease are often non-specific and not exclusive. In addition, symptoms can appear several weeks or months after the animal has encountered an episode of SARA. Nowadays, there is no simple and efficient way to detect SARA in commercial dairy herds. Hence, the objective of the current project is to develop a method to early detect SARA, based on milk fatty acid profile of individual cows from high-producing dairy herds. To reach this objective, milk composition (fat, protein, SCC, and BHB) and fatty acid profile of approximately 100 dairy cows, distributed equally among three dairy breeds (Holstein, Jersey, and Ayrshire), will be determined by infrared spectroscopy from samples collected every other week from 14 d prepartum to 136 postpartum. A pH sensor will be introduced in each cow, and rumen pH will be monitored continuously, during the same period. Based on pH monitoring, if a cow undergoes SARA, milk samples will be collected daily. Relationships between milk fatty acid profile and rumen pH will then be established and integrated in a SARA diagnostic tool that could directly be integrated into Valacta’s service offer. Firstly, this diagnostic tool will allow to benchmark the incidence of this metabolic the incidence of SARA in high-producing dairy herds, which will allow to emphasize the importance of managing herds in a way to prevent the occurrence of this metabolic disorder associated with important animal health and financial issues. Expected results include the development of a simple and non-invasive test, based on milk fatty acid profile, to identify lactating cows that could be at risk for SARA. When included in monthly DHI recordings, this test will allow comparisons between herds as well as monitoring of individual herds and therefore will provide a way to quickly identify herds where management practices can lead to higher prevalence of SARA.