cows in field

Featured Farm: California Organic Dairy Farming: Grazing Green at Cahill Dairy, Ferndale, California Owned and operated by the Cahill Family

By Tamara Scully, NODPA News contributing writer

“It’s a fine line between working with nature and trying to be profitable,” said Zach Cahill, a second generation dairy farmer who co-owns and manages Cahill Dairy, Inc. with his father, Chris. “We monitor every day, to be stewards of the land, and manage employees and animals and keep them healthy and do our best for the environment.”

The Cahills - Zach and wife Kayla, along with his mother, Lea, and father Chris - live and work on their certified organic dairy farm in the town of Ferndale, located in Humboldt County, California. Ferndale, bordered by the Pacific Ocean and “behind a redwood curtain” of dense forests on the other three sides, is home to 39 organic dairy farms, and one conventional dairy, Zach said. The largest dairy in Ferndale milks about 1500 cows, while the smallest herds are under 100 head. Cahill Dairy has 500 milking head.

The family farm’s roots began with Chris, who entered a business agreement with a retiring dairy farmer, making it possible to begin the Cahill Dairy. He started with 40 cows and 40 acres of land in the 1990s. When certified organic dairy farming boomed in the early 2000s, Cahill Dairy, along with almost every dairy in the area jumped onboard. While the premiums were a great incentive, organic just made sense. The Cahills were already maximizing dry matter intake from pasture with rotational grazing, and certifying as organic didn’t require a lot of changes. The primary crop on Cahill Dairy has always been perennial pasture.

Grazing the milking herd is standard practice in Ferndale, where grass is the most valuable feedstock. The area is so remote that purchasing feed is not cost-effective. Luckily, the climate is very conducive to growing grass, and pastures rarely require any type of reseeding or renovation, with the natural grasses and clovers providing abundant, nutritious forages.

“We don’t get the heat units or day lengths to grow many other crops,” Zach explained.

Summer temperatures average around 65 degrees Fahrenheit, while winters rarely go below freezing. With an average of 45 inches of rainfall annually, conditions are almost perfect for growing grass. Grazing cows stay comfortable, too, as heat stress is not a concern. The mild winters keep infrastructure costs low, with out-wintered cows keeping housing costs at a minimum. Ferndale is in a valley, which is bisected by one main river artery, the Eel River. The entire basin sits on a large aquifer which is used to pump groundwater for irrigation.

The biggest weather-related concern is flooding. The Cahill’s barns and houses are all elevated three feet above ground level, to keep them from being regularly inundated. The ground here consists of deep, fertile soils, due to sediment deposited from the regular flooding of the river which runs through the farm. River banks on the farm are planted with willows to shade the water and reduce streambank erosion, and retaining walls shore up the banks in some places as well.

They don’t have issues with erosion or runoff, as the ground is all covered with grass. When they do plow a minimal amount of acreage for corn, it is done very early in the spring, and after harvest the ground is planted to winter cover crops, or back to pasture. And the corn ground is almost always on higher elevation land.

The grazing season here runs from mid-March to late October, and the milking herd, which grazes on 200 acres of irrigated pasture, typically receives 40 - 50 percent dry matter intake (DMI) from pasture grazing. The 150 acres dedicated to grazing heifers and dry cows is unirrigated.

Feed production is primarily silage and baleage, consisting of rye grass and clovers. Dry hay is difficult to make, due to the ever-present fog and the lack of heat. Growing corn is challenging, but they do plant corn for silage, using the shortest day corn they can obtain.

The milking herd is fed a total mixed ration every day at the feed bunk. Less TMR is needed during the grazing season, as pasture is the primary feed for the herd. Lower quality hay is purchased for dry cows.

“Our pasture is our best feed, our cheapest feed. And the cows go out and harvest it,’ Zach said. “Whatever they don’t get off pasture, they get from rolled corn, barley and mineral blend,” plus alfalfa, grass and corn silages, and baleage.

Grazing Plan

The farm consists of 750 acres, both owned and leased. Two hundred of those acres support the milking herd’s grazing on irrigated pastures. Another 250 acres are used solely for feed production, with the remaining acreage used for grazing youngstock.

The dairy has enough land to support grazing for up to 700 milking cows, as well as the facilities to do so. But it doesn’t make economic sense to overstock. Although they are not looking to grow, they will do so strategically when warranted. This year, a family friend is selling his milking herd, and they will be purchasing his cows, and will run dry cows or heifers and raise feed on his acreage.

“We don’t go out looking, but do buy if the cows fit our criteria,” Zach said. “If we increase milk cows, we have to feed them. We need the land base to grow local feeds. We are so reliant on producing our own feeds.”

There are three traveling irrigation guns, and two pumps which run 20 hours per day to water the pastures. The guns are moved twice per day, every morning and evening. The rotation of the irrigation guns depends upon where the cows are going to graze, and where water is needed. Every 10 - 14 days, each piece of ground is re-irrigated.

The milking herd grazes in each pasture, which is further divided into smaller paddocks by temporary polywire fencing, for four or five days. The fields are clipped for thistles and irrigated immediately after the cows graze a paddock. Fields are irrigated once or twice before being ready to re-graze. Typically a pasture is irrigated 10 days after the cows graze, and then again two days prior to the cows moving back onto it, to give the grass “a last shot of re-growth” before being grazed again.

Each pasture is typically between eight and 12 acres in size, and is divided into four to six paddocks. Every 28 to 35 days, the paddocks are re-grazed. They don’t back fence the paddocks, but the cows typically stay together on the fresh pastures, and over-grazing is not a problem. The cows graze in a field up-close to the barn at night, so the morning milkers don’t have to fetch them in from distant pastures. After milking, they are moved further out.

Heifers are kept on a separate ranch, where they graze exclusively. Young stock graze as a group, while breeding-age heifers are separated out onto pasture with a bull. During the winter, the heifers are pastured on some hay ground. Weaned heifers are turned out onto pasture at four or five months old.

Calves are housed in individual hutches until they are three to five weeks of age, at which time they are then moved to group pen, and weaned at three months of age. Individual hutches are placed on tall grass, which serves as bedding, and moved every week to fresh grass. The group pens are located outside, under a loafing shed, so ventilation is not a problem.

Newborn calves are fed colostrum twice after birth, and are tagged immediately at birth. They also receive Inforce 3® Dairy Intranasal vaccine, as well as Calfguard®. Calves are fed with milk straight from the milk line. They receive hay and grain once they are in the group pens. They use organic supplements and additives to bolster calf immune response, and focus on keeping the bedding clean and dry.

Herd Health

The biggest issue with calf health has been with calves from birth to 10 days of age, when cryptosporidiosis has caused death losses. As the microbe resides in walls or the ground, the calves can easily lick a rock, or the screen to the hutch, and ingest the pathogen, so “the issue may be where we raise our calves,” Zach said. They have tried raising the calves on concrete, gravel and shavings in the past, but using the tall grass as bedding seems to work best at preventing the disease.

Cows are vaccinated during the dry period with five vaccines. They utilize their veterinarian as needed for any serious health concerns, primarily calving emergencies, and for herd vaccinations. “It makes financial sense to vaccinate the herd preventatively,” Zach said. “We don’t really have that many issues with cows,” with a bit of mastitis, some ketosis or the occasional case of pneumonia being the only real concerns.


The milking herd is primarily Jersey genetics. Crosses that are purchased over time are bred back to beef semen. Breeding takes places via AI at the feed bunk, which the cows enter directly after milking.

The bulk of the heifers are bred April through August. The bottom 60 percent or so of the milking herd, along with the tough breeders, are bred to beef semen. Ninety percent of the calves born in the winter are beef calves and are sold at one week of age to regular buyer.

The remaining 30 to 40 percent of the cows are bred with sexed Jersey semen, and these calves are born seasonally, to avoid winter months, as they’ve found that Jersey calves born in the winter don’t tend to do well with the wet and cold conditions. They raise almost all of the heifers they need for replacements.

Cows are culled for disease, feet issues, reproduction concerns, high somatic cell counts and low milk production. Culling decisions are based on “whether she is paying the bills or not,” Zach said.

They aren’t selecting for A2 genetics, but have found that in selecting for a moderate-framed Jersey cow with good feet and legs, good udders, and good components their herd genetics are also incorporating A2.


Production varies seasonally, but averages about 45 pounds of milk per cow, per day. The spring flush in April and May boosts production. All of their milk is sold to a local cheese maker, Rumiano Cheese. Fluid milk leaving Ferndale travels 100 miles north for processing. The Rumiano Cheese plant is the second closest processing facility, with one facility located on the outskirts of Ferndale. There are five milk buyers in the region.

Rumiano Cheese “gave dad a chance 30 years ago” and the farm has a good relationship with them, so they see no reason to sell elsewhere.

Because the milk is utilized for cheese, with a small portion for butter, they are looking for total components and total solids. They get bonuses for clean milk, and for butterfat content. Once per month, the milk is tested, with samples taken from some of the cows. Their butterfat ranges from 4.75 -5.2 percent. “The components are all over the place,” Zach said, but they do try to compensate through nutrition.

Components dip during the spring flush, when the cows are out on pasture and producing more milk. They feed additional corn silage during the spring to keep the energy in the cows, and add in a bit more straw - rather than alfalfa - to increase fiber intake and slow down the cows’ digestion. Sodium bicarbonate is also mixed into the ration to help buffer against the extra starch and acidity from the corn.


The cows are now milked in a new tail-to-tail, double-12 pit parlor, built five years ago. It was designed for labor efficiency. Two milkers can now milk 125 cows per hour. The parlor also serves to keep their good employees on the job, including several who have been employed for many years, making it easier for them to continue to do the job of milking. Aside from Chris and Zach, there are six other full time employees on the farm, and a few others who help out with the irrigation during the summer months.

The new parlor was also designed to “create an environment that was more conducive to employee health and ease of milking,” Zach said.

The freestall barn is accessible to the milking herd if it is cold and wet, or if the fields are flooded, but the herd is on pasture year-round, day and night. The freestall is bedded with sawdust from the local logging industry, which is inexpensive and works better than sand, which they have used in the past.

There is a compost bedded pack barn for the close up dry cows or freshly weaned heifers. The bedded pack is cleaned out and either composted in windrows, or hauled directly to the field for fertilizer depending on season and need.

Manure from the feed bunk is scraped into the alley, and a newly-installed manure separator has eliminated the need to direct haul daily. Instead, the dry solids are now separated out and can be stored to apply as needed to the fields, optimizing fertility and increasing labor efficiency. The liquid waste is pumped out to be sprayed on the fields.

Farm Living

After graduating high school, Zach was determined not to be a dairy farmer, and left home for college. He realized that other people did not have the advantages he had growing up on a dairy farm, and began to fully appreciate the beauty of his hometown. The organic dairy program at Chico State was “a very beneficial experience” and he returned home with a renewed interest and passion in dairy farming.

Zach and Kayla were married on the farm, after the family took an old dilapidated heifer and storage barn, and renovated it to host their wedding. The barn now hosts 25 weddings each year, with Lea serving as wedding planner and hostess.

Later this year, the barn will host the WODPA conference. The Cahills invite all NODPA readers to come out to the farm and participate in the conference this November.

“It does get used for dairy purposes,” Zach said, although only for a few months of the year.

Zach and his father had to negotiate with his mother to have use of the barn, too. The deal is that they get to use it for hay and equipment during the winter months, and it’s hers to use the rest of the year as a wedding and event venue.

The farm also has another set of regular visitors, who make their presence known twice each year, during their spring and fall migrations. Aleutian geese, numbering about 200,000, visit the pastures twice per year.

The focus at Cahill Dairy is on profitably running a dairy farm in a manner which provides for animal welfare, human well-being and environmental stewardship. It’s a balancing act: one that Zach doesn’t take for granted as he proudly works alongside his father, supporting his family, their employees, the cows and the land by farming without harming the unique ecosystem found on the farm, and in the Ferndale, California community.

“The nature of organic dairy farming is a combination of working with nature and running a business,” Zach said. Cahill Dairy is successfully doing just that.

Zach Cahill, Cahill Dairy, Inc., 1837 Home Ave, Fortuna, CA 95540, can be reached at 707-599-5194 or by email: