Milk quality efforts can pay off in cow health and bottom line

Jan Shepel
Dr. Scott Earnest, DVM, right, a bovine practitioner and milk quality specialist with Lodi Veterinary Care in Lodi, offers farmers advice about practices they can use on their farms to improve milk quality, potentially earn premiums for the quality of their milk while at the same time improving their cows’ health.

LODI – With milk prices and markets as tough as they are today, it’s in a dairy producer’s best interest to optimize the value of the milk that’s marketed from the farm.  Farmers may get significant cash bonuses for low somatic cell count (SCC) milk marketed. However, there are other benefits to be gained from reducing cell counts that may not be as obvious – both in terms of animal health and in bottom-line numbers

Dr. Scott Earnest, DVM, a dairy practitioner and milk quality specialist with Lodi Veterinary Care (in Lodi) notes that quality bonuses for milk can be as much as 78 cents per hundredweight for milk testing in the 100,000 SCC range or lower. But for milk with cell counts up around 350,000, generally those premiums drop from the milk check.

Speaking to a group of dairy farmers, Ernest explained that this low-cell-count premium is a good goal to shoot for, but doesn’t fully reflect the financial impact of cows that register higher SCC during their lactation. Earnest referenced a study done by Mark Kirkpatrick DVM, MS, which included 170,000 Holstein cows that showed another important impact of elevated cell counts: cows starting their lactation with cell counts over 200,000 were found to produce 1,583 pounds less milk in the first seven months of their lactations.

Calculating that loss at $17 milk, the financial hit due to cell counts above 200,000 during those first seven months totaled $269. Cows starting out with elevated cell counts were found to have three times the rate of culling, compared to their herdmates, within the first 60 days of lactation. Based on the Kirkpatrick study and his own experience, Earnest reported that cows with cell counts above 200,000 require an extra 17 days longer to become pregnant than their herdmates. These high-SCC cows are also 2.5 times more likely than their lower-SCC herdmates to develop mastitis.

Earnest urges farmers to do monthly SCC testing with the Dairy Herd Improvement Association (DHIA) where milk weights are measured and milk samples are analyzed individually for somatic cell counts.  While many farmers have milking parlors with their own milk meters, in general this milk-meter conductivity does not adequately replace the cell count testing that is done by analyzing milk samples taken from each cow on test day, the vet said.

The reports that come back from DHIA on each cow are invaluable and that data can be turned into higher performance on the farm, if used properly, Earnest said.  Specifically, there are reports on fresh cows that come in with high cell counts, on cows with new infections and on cows that appear to have chronically high cell counts.

Earnest also strongly recommended that farmers do monthly bulk tank sampling where cultures for pathogens like mycoplasma and prototheca are included. Prototheca is an algae that can infect cow’s teats and tends to spread from cow to cow.  As a practicing vet, Earnest said he tends to see prototheca more on farms where recycled sand is used for bedding.  The results of these tests should be shared with the farm’s whole management team, he added.

The routine bulk tank sampling may be used to screen for the worst pathogens.  If they are found, the search can begin for individual infected cows, which is done with individual cow sampling. When prototheca is found, veterinarians advise that the cow be culled; prototheca is incurable and an infected cow will tend to spread around that algal problem to others in the herd.

Another standard operating procedure for improving milk quality in the bulk tank is to systematically screen fresh cows for elevated SCC at two to three days in milk.  This regular, routine screening should include testing each of the cow’s quarters with a California Mastitis Test (CMT).

Lodi veterinarian Dr. Scott Earnest demonstrated the use of the California Mastitis Test or CMT - a key tool in determining milk quality. He recommends testing cows with the CMT paddle and reagent, along with routine bulk tank cultures, testing and culturing cows with known high cell counts and treatment or culling of those animals.

In using the CMT, reactive liquid is mixed with a teaspoon of milk (2 cc) from each quarter in a plastic paddle that keeps milk from each quarter separated. If there is no change in this fluid, the milk is negative for high cell counts. The reaction between the fluid and the milk becomes stronger as the cow’s cell count rises. When the reaction is a “strong positive” Earnest said it will “look like a fried egg.” Positive reactions that are lower will create a thickening of the reagent/milk combination in the paddle.

Then, any quarters that test positive on the CMT should be sampled for a milk culture, which is done in laboratory – something Earnest and his colleagues do routinely in their Lodi lab. Based on the culture results, these affected quarters should be treated based on protocols designed by the herd’s veterinarian and herd manager.

The method to get a good milk sample for culturing involves putting on clean gloves, prepping the teat as it would be prepped for milking, then thoroughly cleaning the end of the teat with alcohol and stripping milk from the teat. The first strip goes on the ground, Earnest said, and the next three go into a clean sample bottle.

“If you end up getting a lot of contaminated cultures you may need to re-train the cow handler on sanitation techniques,” he added.

Earnest advised that fresh cows with high cell counts and cows with new infections should be CMT-tested, with affected quarters getting cultured and treated. Those cows with chronically high cell counts should get the same protocol – except possibly for treatment. The producer may want to consider culling the animal or killing the affected quarter on the recommendation of the herd veterinarian.

Multiple elevated tests in the same lactation may make culling a better option.

“Seven high tests in one lactation makes that cow not a great candidate for keeping her and killing the quarter, but if you like the cow, you can try to kill the quarter and see how she does,” he told the group of farmers.

Earnest stresses to farmers that they should make this kind of testing a standard operating procedure and do it on a regular basis.

“Pick a day early in the lactation and do it on a routine basis,” he said.

The computerized dairy record-keeping program Dairy Comp 305 can generate reports that show how much milk is being lost due to treating and dumping the milk from these high-SCC cows. There is also a report that can show how much milk quality is being lost by individual cows – based on how high her cell count is and how much production she makes.  That will show the farmer how much milk quality will improve if that cow is cleaned up or culled.

Earnest stressed that improving milk quality will pay dividends in both the health and efficiency of the herd and in bonus premiums for lower cell counts.  But consistently achieving top-quality (low-SCC) milk must be done with systematic, routine procedures that include both bulk tank milk quality sampling and testing of milk from individual cows.