Current Progressive Dairy digital edition

Check out my lab: Green Valley Dairy

Progressive Dairyman Editor Peggy Coffeen Published on 11 March 2014

Green Valley Dairy’s on-farm testing lab provides timely turnarounds for milk cultures and much more.

Manager John Jacobs Jr. operates the 3,500-cow dairy near Krakow, Wisconsin, with his father, John; uncle Mark; brothers Paul and Joe; and partner, Ken Peters.



john jacobs

John Jacobs, Jr.
Green Valley Dairy
Krakow, Wisconsin

“It started out as a milk culturing opportunity, and it has continued to expand,” Jacobs says.

He describes his lab in three words: “small, simple and clean.” The dedicated workspace includes a countertop, sink, refrigerator and storage as well as two incubators and a microscope. He purchased his lab equipment online.

A basic compact incubator is used for general bacteria growth.


“On the milk quality side, it gives us better information for treating our clinical cases of mastitis,” Jacobs adds. He cultures milk samples to differentiate gram-positive from gram-negative mastitis pathogens. Plate growth is compared to an identification chart, and that information drives treatment decisions.

The timeliness of these results can’t be beat. Plate growth from positive clinical mastitis cultures is visible within a day.

“We don’t have to wait,” he says. “In 18 to 24 hours, results are in-hand.”

This incubator is also used to check up on the cleanliness of items such as towels, bottles and feeding tubes.

“When we culture these, we are looking for general bacteria growth,” he says. “That simply tells us whether or not things are clean and if our protocols are being followed to ensure quality standards and animal health.”

John Jacobs, Jr.'s lab


A carbon dioxide incubator gives the dairy the ability to test for mycoplasma bacteria. Their protocol is to sample every fresh cow as a quality control measure. After spending seven to 10 days in the incubator, a microscope is used to identify growth.

Jacobs’ lab gives him further in-house capabilities. Milk from all fresh cows and treated cows is tested for antibiotics, and though not often used, he has the ability to test for meat residues as well. This space is also a staple part of the calf program; here, colostrum quality is measured and blood serum tests are conducted to determine passive transfer.

Though his background is in business, not biology, Jacobs embraced the challenge of learning the science of culturing when he left his career in finance to join the dairy six years ago.

He studied up on the subject using university resources, particularly Minnesota Easy Culture System II, and consulted a veterinarian for training. Jacobs has since trained employees to perform cultures and read results.

“We may be intimidated by science and biology, but nonetheless, the core concepts are pretty simple to get your arms around and understand,” he adds.

The lab is located near the dairy’s offices, which line a hallway near the milking parlor. While close enough for convenience, it was important to separate this room and dedicate it to the sole purpose of laboratory work.

“In the office area and away from the cows, we are better able to maintain its integrity and sanitation,” Jacobs adds.

For others considering adding an on-farm testing lab, Jacobs advises seeking university resources and talking to a herd veterinarian, and he maintains that the concept is basic.

“All you really need is a refrigerator, countertop you can keep clean, incubators and storage for testing materials,” he says. “Keep it simple.” PD

Do you have a great structure or feature of your dairy? If so, we want to check it out! It could be your calf barn, shop, office – any area on your dairy that you have designed to be your ideal space. Please share them with us by email .

peggy coffeen

Peggy Coffeen
Progressive Dairyman