The somatic cell count (SCC) is a common benchmark used in mastitis management. Testing of the SCC of composite cow milk is done every 3 weeks to 6 weeks. Additional measurements between milk controls can help with the early detection of changes in udder health. Therefore,
Cow health, Milking
Lely has developed the MQC-C, to get more frequent insights into the conductivity gradient. The MQC-C is an automated California Mastitis Test (CMT). The CMT is by no means comparable to laboratory SCC in terms of test characteristics and accuracy. Its true value is that it gives a daily insight instead of a monthly report. The MQC-C works for only a fraction of the laboratory costs. It is a promising tool for the (early) detection of (sub)clinical mastitis for each individual cow in the herd.
The principle of the MQC-C is based on an automated CMT, by taking a fixed volume of well-mixed composite milk from a milking. The milk is mixed with a fixed volume of reagent, after which the viscosity of the mixture is measured. The measured viscosity is transformed into a value, expressed in cells/ml, based on a calibration curve.
Deng et al., 2020, found that the automated CMT and the Laboratory SCC test are related. By comparing the automated CMT measurements with laboratory SCC measurements on milk from the same cow on the same day, they were able to provide an insight into the practical usability of the automated CMT measurements. The relationship was better when averaging the automated CMT tests over a 24-hour time window. This corresponds to the method Lely uses.
When a farmer wants to use the MQC-C on his farm, it is important to equip all the robots in a group with an MQC-C, since the added value is in the high measurement frequency. Up to now, Lely has sold 65% of all Lely Astronaut A5 robots with an MQC-C.
To maintain an insight into a cow’s conductivity gradient, it is necessary for the measurement always to be taken the same way. Therefore, it is important to handle the MQC-C accurately in order to increase its effectiveness. The following procedures are important:
1) Refill the MQC-C strictly according the manual. The quality of the mixture is very important.
2) Refill the CMT reagent in time. Field experience has shown that this may also affect the correlation between the online CMT and the laboratory SCC.
Figure 1 Illustrates how the automated CMT shows the same trend as the Laboratory SCC, while it provides additional information on short-term high SCC episodes or flare-ups on the in-between DHI test days. Therefore, automated CMT testing seems more valuable in terms of individual cow udder health monitoring for a number of reasons:
The measurements may also be used to identify subclinical mastitis cases that warrant further diagnostics, such as bacteriological culture to explicitly identify the mastitis-causing pathogens. Further research to link the automated CMT patterns to pathogen species would be useful and highly relevant for developing tailor-made treatment plans to further optimise treatment strategies.
Think about early intervention in mastitis and well-established dry-off treatment decisions. There will therefore be less chance to spread infection and the effectiveness of treatment will be increased. Because of its high measurement frequency, this test also provides a good opportunity to monitor treatment effects. Figure 1 (B) suggests, for example, an infected udder that was cured and subsequently reinfected. You might consider a bacteriological culture. When a cow displays a pattern like (A), you might decide to cull her, or use antibiotics at dry-off. MQC-C is a reliable and practical screening tool. It indicates suspicion of disease and is applicable on a large scale and is therefore a supportive decision-making tool.
Figure 1. Deng et al., 2020, for different SCC patterns, to demonstrate the value of frequently measured online SCC in individual cow udder health monitoring. This is on log scale, which is a way of displaying numerical data over a very wide range of values in a compact way. (A) indicates a chronic intramammary infection; (B) suggests an infected udder that was cured and then subsequently reinfected; (C) shows a cow likely to be suffering from a chronic IMI with a fluctuating SCC pattern; and (D) probably represents a healthy udder with one brief high SCC episode. The triangles represent laboratory-measured SCC results. The dots connected by a line represent the MQC-C measurements averaged over a 24-hour time window. The dotted horizontal line represents 200,000 cells/ml.
The MQC-C is a promising on-farm tool for the detection of cows with a high cell count. It gives an insight into udder health for every individual cow in a herd on a daily basis. The MQC-C measurements can help with the farmer’s mastitis management in terms of early detection, dry-off treatment, adapting treatment to an individual infection (longer treatment for a real recovery), etc. For more background information you can read the article by Deng et al., 2020.
