Name: Comparison of milk L-lactate concentration and the California Mastitis Test in identifying...
Uploaded: 2025-06-02T06:41:27.000Z
Duration: 14 min 55 s
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So, this morning I'm going to talk about the ability of milk lactate concentration for identifying quarters with high somatic cell count in dairy cattle at dry off.

So, I'm going to start with a brief introduction about mastitis.

I believe everybody in this room knows that the mastitis is probably the most important health problem in dairy farms worldwide.

So, mastitis comes in two forms, when the udder or milk is showing any abnormalities.

But the problem when the udder and the milk looks normal and the milk has bacteria in combination with high somatic cell count.

In that case, we call subclinical mastitis.

So, the prevalence of subclinical mastitis is 40 times higher than the clinical mastitis.

This means that if you have one cow suffer from clinical mastitis, you have to expect that you have around 40 cows suffer from subclinical mastitis and you don't know.

So, the question is, what's the problem of subclinical mastitis?

So, everything is normal, milk is normal, udder is normal, cow health looks normal.

But the problem of the subclinical mastitis is subclinical mastitis cause direct drop in milk production.

So, several studies reported negative correlation between the somatic cell count and the milk production.

Cow with somatic cell count around 200,000 cost the owner around $90.

Increase the somatic cell count to 400, so it's going to cost the owner around $110.

And 75% of this cost is due to loss in milk production.

Not only that, but subclinical mastitis cause changes in around 20 component of the milk, which has negative impact on the processing capacity and shelf life of milk.

Furthermore, the problem of subclinical mastitis is not a stop at the level of the cow suffer from subclinical mastitis, but this cow act as a source of the infection.

It's going to distribute the infection to the healthier cow.

So, subclinical mastitis is a hidden enemy.

And to control it, to treat it, you have to identify it.

And this is the biggest aim of our project.

As we mentioned that the subclinical mastitis cause it changes in around 20 parameter or 20 component of the milk.

So, everybody in this room know that the lactate is physiological byproduct of anaerobic glycolysis, which enhance it in case of decreased oxygen tension and increase the rate of... increase the metabolic rate of the cell.

So, in mastitic milk, so the concentration of oxygen is decreased and the activity of somatic cell all the time at the beak because it's all the time fight the infection.

So, lactate normally present in the milk with concentration around 0.1 millimole.

However, in case of mastitic milk and the presence of bacteria...

So, some of these bacteria are lactate producing bacteria such as group B streptococcus.

And you can see the huge difference between the streptogalactia or group B streptococcus and the E. coli regarding the production of lactate.

But all these sources is not the main source for the milk lactate concentration.

The main source for lactate concentration or the milk lactate is the somatic cell count.

There is two important case study reported that there is a positive linear association between the somatic cell count and milk lactate concentration.

In bacterial meningitis in human, they found that the neutrophil... increase the neutrophil associated with increase the cerebrospinal fluid lactate concentration.

So, we can probably say that the neutrophil is the main source for the milk lactate concentration and for the higher milk lactate concentration in mastitic milk.

So, milk lactate concentration is increased around tenfold in subclinical mastitis and around 40 fold in clinical mastitis.

So, the important question right now, so why milk lactate over other mastitis indicator?

The answer of this question is because the biggest advantage of milk lactate is extent and the speed of its concentration change.

With the milk lactate increase within 24 hour from the infection.

So, you can catch the infection, the new infection within 24 hours just measuring or monitoring the milk lactate.

So, the last few years or so, there is several handheld meter are available in the market for monitoring plasma lactate concentration and used for evaluation, evaluating the physical performance and optimizing the training protocol for athletes.

One of the most popular meter used in United States is called Lactate Plus.

Because it's the cheapest meter available in the market.

The next meter, the cost of the strip cost around 2.5 or 3 dollars.

So, this is the cheapest meter available in the market.

And the second important character for this meter is the measuring range.

So, this meter measure lactate concentration from 0.3 to 25 millimole.

This meter use electrochemical lactate oxidase biosensor.

And we believe that this meter gonna work good in milk.

So, our hypothesis, therefore, our hypothesis was, we hypothesized that the milk lactate concentration measured by Lactate Plus handheld meter will provide a clinical useful method for identifying quarter with high somatic cell count.

And consequently, our objective for this study is to evaluate the clinical performance of measuring of milk lactate concentration measured by Lactate Plus for identifying quarter with high somatic cell count compared to California mastitis test, which is most popular method used in the practice.

So, we done this study in University of Illinois Dairy Farm, which around five minutes walk from the vet school.

And interesting, we have a nice park here.

So, designed by Japanese guy and called Japanese Park.

We collected around 419 quarter for milk sample from 105 cows at the last week of lactation.

Because as you can see on this figure that the highest rate of the new infection occur at dry off.

And we used the four milk or the cisternal milk that we collected.

The milk sample was in 50 second from touching the other.

Because the four milk or the cisternal milk is considered the most predictive fraction of the milk used for diagnosis of subclinical mastitis.

Then we measured the somatic cell count semi-quantitatively using the CMT and quantitatively using DeLaval cell counter.

The DeLaval cell counter measuring range starting from 10,000 to 4 million cell per milk.

After that, we measured the milk lactate concentration using lactate plus.

So, the meter show low when the concentration of milk lactate is lower than 0.3.

For statistical analysis for the correlation or the association between the somatic cell count and the milk lactate concentration, we calculated this permanent correlation.

And based on that, we identified the quarter with high somatic cell count.

As we gonna see in the next slide, we found that the meter showing higher correlation at the level of 1 million cell per milk.

So, we identified the quarter with high somatic cell count is higher than or equal 1 million cell per milk.

To characterize the relationship between the lactate plus hand-held meter and CMT comparing to the DeLaval as a reference method, we used logistic regression.

So, we build a ROC curve for each logistic regression model and we calculated the area under the curve for each ROC curve.

Sensitivity and specificity at the optimal cut point was calculated for each ROC curve using Uden index.

Also, we calculated the positive likelihood ratio by dividing the sensitivity with 1 minus the specificity.

So, the method or the test with positive likelihood ratio more than 10 is considered excellent diagnostic test.

BLSN 0.5 was considered significant in this study.

So, for the results, as you can see, this is a scatter plot characterized the relationship between the DeLaval somatic cell count and the milk lactate concentration.

And you can see that the lactate plus hand-held meter started to correlate excellent with milk lactate concentration.

It showed the same result that milk lactate concentration measured by laboratory methods was correlated significantly with the somatic cell count after 3 showed 1 million.

And this is support the fact that the main source for milk lactate concentration is the somatic cell present in the milk.

So, that CMET is still showing the highest correlation with DeLaval somatic cell count.

So, it's different from 1 to 1, different from study to study.

But, in this study, CMET is showing highest or higher correlation comparing it to milk lactate concentration.

For the logistic regression, so this is the ROC curve.

So, the result of logistic regression showed that the milk lactate concentration of more than or equal 0.4 provide an excellent quantitative test for identifying quarter with high somatic cell count with higher sensitivity compared to CMET.