Total mixed rations (TMRs) is big business.

These rations are a combination of grains, forages, minerals, protein feeds and additives, and formulated by a dairy nutritionist to provide the optimized nutritional package needed to maximize milk production, reproductive capability and cow growth. Dairy farmers don’t all utilize TMRs. Many feed grain and concentrates separate from pasture forages, known as a component system. Others are increasingly returning to pasture-based diets.

A lot of research has gone into rumen digestion and enhancing rumen fermentation via the correct mix of carbohydrates and protein in the dairy cow diet. For the milking herd, TMRs allow precise formulation of ingredients, mixed to reduce selective eating and targeted for maximum milk output from high-production cows.

“A TMR is balanced to meet the nutritional needs of the dairy cow. By balancing the ration, the cow is able to more effectively use the nutrients provided to her, allowing for greater milk production and a decrease in nutrients being lost to the environment,” Penn State Extension Dairy Educator Mathew Haan said.

What about cows grazing on lush pastures, feeding themselves ingredients such as pasture forages that are best suited to their digestive capabilities? Cows are, after all, ruminants. They are a class of ruminants – grass/roughage eaters – whose rumens are designed to primarily digest grasses, although they can also digest legumes as a portion of the diet without sacrificing rumen function.

Milk from grass

Some dairy farmers make milk from 100 percent grass, without added grain. Perhaps one of the best known Northeastern region creameries featuring 100 percent grass-fed milk is Maple Hill Creamery, in Stuyvesant, New York. Now featuring milk from over 70 regional producers, the creamery began as a small family dairy farm. They fed grain as well as seasonal pasture, became certified organic, then transitioned the cows to 100 percent grass. Feeding grass exclusively, according to the company’s website, created healthier cows, as well as a premium product designed for consumers increasingly concerned about the health of the animals that produce their food.

Making milk without TMRs, without any grain, and from 100 percent grass and legume forages is possible, and can be done profitably. Maple Hill Creamery now has products – a variety of yogurts, kefir, mozzarella, and other raw milk cheeses – available in large retailers in all 50 states.

“Cows can produce milk on 100 percent grass,” Bradley Heins, associate professor, Organic Dairy Management, West Central Research and Outreach Center, University of Minnesota, said. According to Heins, production is maintained by providing high quality forage and having a diverse mix of pasture. “Cows will have less production on 100 percent grass, so yes, you probably would lose peak production, but it would be more persistent across lactation.”

In a dairy cow diet, protein and energy intake need to be balanced. If the amount of energy from carbohydrates is too low in relation to protein, milk urea nitrogen (MUN) levels will increase as the cow’s metabolic system works to remove excess ammonia, which is then converted to urea in the liver. The excess urea becomes MUN, which is an indicator of wasted energy – energy not used by the cow for milk production or growth. Excess nitrogen not only appears in milk; it is also excreted in the urine and feces as an undesirable waste product.

“A dairy producer managing a 100 percent grass or pasture-fed herd can change the mix of forages in the pasture (less legumes, more grass) and when cows graze (graze taller, more mature grass) to compensate for higher protein in the pasture,” Haan said. “Typically, protein is in excess and energy is limiting for pasture based herds. In a 100 percent grass-fed dairy herd, cows will never be able to produce at the level of a well-managed confinement TMR-fed herd.”

The higher protein content often found in pasture typically means that energy is a limiting factor in the grass-fed herd’s milk production. With pastured cows utilizing more energy – as they walk around to and from the barn for milking, and to graze, reach water and find shade – than confined cows do, balancing the energy in the diet becomes more critical.

“How are you going to get some energy into your cows?” That’s the question grass-based dairy producers need to consider, Karen Hoffman, USDA-NRCS resource conservationist, said.

Hoffman encourages grass-based dairy producers to address excess pasture protein by utilizing it, or diluting it. For 100 percent grass-based producers, feeding dry hay to dilute the protein can increase the energy available to the cow. Molasses, which contributes energy to the diet in the form of sugar, rather than starch, can also be added to hay or baleage to add energy without grain. For those not wishing to be 100 percent grass-fed, but wanting to restrict grains, adding a small amount of ground corn will provide needed energy.

Hybrid approach

Producers wishing to pasture dairy cows do not have to be grain-free. Even certified organic dairies are not required to give up grain feeding. Instead, certification requires that no less than 30 percent of the dry matter intake (DMI) comes from pasture, and that the animals are pastured a minimum of 120 days, or longer, depending on the grazing season. Animals must also be allowed outdoor access daily, except in extreme conditions. Any grain or other feeds or supplements must be certified organic.

“I look at pasture as an ingredient in my TMR,” Pennsylvania Dairy Farmer Matt Bomgardner said. “When I look at it as an ingredient, it causes my TMR to balance the grass, thus helping me reduce costs and keep production up. My TMR is used to provide fiber and energy.”

Bomgardner has a 100-cow milking herd, 100 acres of pasture, 50 additional acres and two family members working the dairy. The herd’s diet is now 70 percent forage based, from pasture and hay or baleage. He is transitioning to certified organic production, increasing reliance on seasonal grazing while making baleage or hay from excess spring pasture growth.

Although he will continue to feed a TMR, Bomgardner’s goal is to reach 40 to 50 percent intake from pasture, above the 30 percent DMI required for organic certification. He grazes at 12 inches, which he has found to provide the most intake per bite. He moves cows at least twice per day to keep them from grazing down a paddock, and rests paddocks anywhere from 20 to 60 days, depending on regrowth.

According to Martin Hall, Penn State Forage Specialist, cows should graze pasture when forages are tall, and not graze them too low. This technique optimizes the dry matter intake (DMI) available per bite of forage, which means cows spend less time eating, and more time ruminating, which is the objective. Maximum pasture DMI is about 40 lbs/day, but if grazing forages are low – when they are only 4 inches in height – available DMI significantly decreases to 50 percent of that amount.

“I have found no loss of milk production with up to 40 percent intake from grass. Intake appears to start dropping as I move to 50 percent grass, but I feel the loss of income is justified by the savings in feed costs,” Bomgardner said. “I can achieve viable production on grass.”

Bomgardner monitors feed refusals and decreases the amount of TMR fed when the cows are leaving rations in the bunk, assuming that they are making it up grazing. He brings cows off of pasture prior to milking and feeds them the ration. This way, the cows eat the amount of TMR they need to be full, can ruminate while being milked and then return to pasture ready to graze.

“We try to keep the cows full as much as possible while still allowing them to maximize pasture intake,” he said. “When it comes to pasture acreage, I feel the more pasture I can have accessible to cows, the better.”

Moving to grazing

Grass-based dairy producers manage pastures intensively. From seeding to grazing management and cropping fields for hay or baleage, providing a high-quality diet, year-round is key to herd health and production. With amount and quality of pasture constantly changing, producers pasturing the dairy herd for grass-based production need to balance available pasture, pasture quality and any supplementation they are providing, to optimize cow nutrition.

“I think there is a lot of opportunity for a middle ground where a producer combines a pasture based system with supplemental TMR feeding,” Haan said. “The producers that are using this type of system need to have an accurate estimate of how much the cows are eating on pasture and what the nutritional value of that pasture is, along with a method to adjust the TMR portion to meet the nutritional needs of the cow. A challenge with this system is that the amount of the available forage and its quality is always changing, so the dairy farmer and nutritionist are shooting at a moving target when developing the TMR.”

If moving into grazing from a confinement dairy system, establishing high-quality pasture and easing the herd onto grass is the method recommended by Heins. Cows will need to be supplemented to allow rumens to adjust to grass-based diets. Selecting cow genetics that match the dairy’s climate, facilities, use of pasture, pasture quality and profit goals is key, he said.

Conventional Holstein genetics is not most suitable for grazing. Popular grazing breeds include Jerseys and New Zealand Friesian. Those with Holstein herds often begin to select for grass, cross-breeding with breeds more equipped to foraging on pasture.

“Typically U.S. Holsteins are not desirable for a grazing dairy. Their large body size and genetic potential for producing large amounts of milk means that they cannot get all the nutrition they need from a pasture,” Haan said. “I also see more cross-bred cattle on grazing farms, as these farmers look for the right mix of genetics that meet their management style.”

“I have found that I must breed for a ‘grazing cow’ that holds condition and is capable of walking to and from pasture for many lactations. My Holsteins have culled themselves out as I’ve increased pasture intake,” Bomgardner said.

Herd health

Many pasture-based dairies report increased herd health compared to confined herds, or those fed primarily grain-based diets. Producers report reductions in lameness concerns when herds move to pasture.

Metabolic issues, problematic in confined herds fed TMRs, occur much less frequently in pasture based operations. On pasture, flies and parasites may be more of a problem than in confined dairies, Haan said.

“I feel there are many benefits to having a grazing dairy instead of a confinement one,” Bomgardner said. “Our barn is old and will hinder milk production. We are able to get the cows outside where they can get their own feed. They last much longer and we have much less labor in the barn. I’ve also found that less grain leads to healthier cows. I find less mastitis and better response to treatments.”

There are many good reasons for introducing grazing back into the dairy system, including increased herd health; reduced labor and equipment costs; less time spent on cropping the fields for grain production or preparing and feeding rations; and potential premiums for grass-based milk, such as organic or 100 percent grass-fed. Feed, equipment, labor and veterinarian costs can all decrease when cows harvest the majority of their food themselves, spend most of their time on pasture and aren’t prone to injuries or illnesses common to confinement herds. For many, the benefits outweigh any production losses.

“Obviously, producers would be concerned about lower milk production, but you have to look at overall profit,” Heins said. “Profitability of grazing can be just as good, if not higher, compared to conventional dairies.”