Many dairy farmers across the U.S. continue to look to their pastures as a source of nutrition for their milking herds.
Yet because grasses and legumes have their own biological life cycle, the nutrition they are capable of providing to dairy herds waxes and wanes during the course of a growing season. In regions of the country where weather and rainfall is unpredictable, depending on pastures as reliable nutrition can be risky business.
Getting the most out of a pasture, especially for consistent milk production, is both an art and a science.
While pasturing herds of milk cows has mostly disappeared in many areas of the western U.S., the eastern half of the country, with its smaller herd sizes, topography and greater amounts of rainfall, has a greater propensity to pasture dairy cows, at least for a portion of the year.
From the Canadian border to the Gulf of Mexico, forested and rolling terrain that makes row-cropping difficult is oftentimes better suited to pasturing or baling hay.
Pastures provide forage, and forage is the foundation of dairy cow diets. The higher the quality of any forage – meaning the more of it that can be fermented and turned into energy in the rumen – the greater the value of the pasture and its contribution to a dairy’s milk production and profitability.
Ironically, forage is the least digestible part of a dairy cow’s diet. So it is every bit as important that pastures are managed as aggressively for high-quality forage as a field that is being mown for hay or haylage.
In Bernardston, Massachusetts, dairy farmer David Duprey milks about 60 cows that receive a conventional diet of corn silage, grain and hay. But the cows are also turned out on pasture several hours each day for many months of the year.
Duprey’s dairy is located in the rugged hills of north-central Massachusetts, just a few miles from the Vermont border. This country is heavily forested with maples, oaks and pines, and criss-crossed with hundreds of rivers and streams. In what amounts to the cooler climes of northern New England, pastures of seasonal grasses such as orchardgrass, fescue and timothy flourish in the dales that have been cut from the forests.
Duprey has spent his dairy farming career focusing on keeping his pastures productive – both for grazing as well as hay production. He has never grown corn, preferring to purchase high-quality silage from a neighbor.
His property is blessed with good soil, and about 40 acres that are closest to the dairy facility are used for grazing during the spring and summer months.
And while maximizing milk production is his main goal, and diets are designed to produce 20,000 pounds of milk per cow, he also must work with what Mother Nature gives him in his pastures and cropland, knowing that some years the grass is better than in others, and the milk production reflects it.
Smaller-sized dairy herds with their inherently lower labor efficiencies will find they can mitigate some of that inefficiency by maximizing forage dry matter through pasturing, thereby saving on purchased feed costs.
Many dairy farms of similar herd size with acreages that can be grazed are moving toward a “managed intensive grazing” model to reduce operating costs, improving feeding efficiencies as well as being better stewards of the land.
After many years of “trying to figure it out,” Duprey has settled on a combination that uses both his home-grown forages as well as purchased feedstuffs that provide nutrients a heavy forage-based diet cannot provide.
Duprey notes that he’s been down the road of intensive rotational grazing, but the shape of his property and paddocks make it impractical to do a good job of it. He also admits that the older he gets, the less inclined he is to put the effort into moving fences multiple times per day to properly maximize feed dry matter production.
His pastures lend themselves more to a system of “strip grazing” in which an electric fence is moved in a paddock, gradually increasing the size as well as the pasture available for grazing as the paddock grows in size.
Every year is different, explains Duprey. One summer is cool, the grass is growing well and the cows are always ready and willing to go out and graze. The summer of 2016, on the other hand, was hot and humid for many weeks and the cows were not interested in going out, even though there was lots of shade to keep them out of the sun.
The pastures, too, were not as productive due to the lack of rainfall. By mid-summer, the grass that did grow was obviously stressed and lower in quality.
However, in the spring of 2016, Duprey was able to harvest 450 round bales off of his hay ground, admitting the quality was mediocre.
The heat came on hard and fast shortly thereafter, and the second cutting yielded only 150 bales – again with only marginal quality. There was not enough grass to bother going out for a third cutting. As the weather cooled in mid-September, the cows were going back out and spending more time on the pasture.
At the heart of getting the most out of pasturing dairy cows is the dairy farmer’s ability to optimize forage quality over the course of a growing season while not over-grazing and damaging the pastures.
While Duprey is an excellent manager of his pastures, he admits he doesn’t have an accurate idea of how much dry matter the cows consume while on the pastures, due to the variability of the amount of grass and its quality.
The base milk cow ration of corn silage, grain and baled hay remains fairly constant, and Duprey can tell by the way the cows clean up the TMR how much pasture they are consuming at any given time. If the cows really like the pasture, TMR consumption declines; if they aren’t liking the pasture, he must increase the TMR.
With years of practice and an intimate knowledge of his land, Duprey knows how to tweak the diet to keep the desired amount of milk in the tank. The milk production varies but, as is often the case, milk components can make up for the difference in volume.
Duprey takes the best of what his pastures have to offer and balances his herd’s diet around what the pastures contribute. As most dairy farmers have been trained to do, Duprey will take a very critical look at the cost of grain relative to the milk price before he spends more on that commodity.
It’s all about balancing costs against what can be expected in return in the milk tank – and the milk check. Even though Duprey has a silage and grain bill that must be paid every month, the pasture and hay are paid for by the time the cows eat it. 
PHOTO: While there are months in Massachusetts not amenable to grazing, David Duprey is able to graze his cows for several months to maximize what his pastures offer. Photo by Debbie Duprey.
-
John Hibma
- Consulting Ruminant Nutritionist
- South Windsor, Connecticut
- Email John Hibma
