And while these things are very common, one of the staples of dairy farming remains tried and true: grazing dairies.
Many areas of the country still produce pound after pound of milk from cows that consume much of their dry matter intake from growing forages. This is where much of the industry got its start, with cows consuming free-choice pastures, whatever was available along with hay also produced on the farm, along with feeds and concentrates fed in the parlor, outside or in a feed lane. These various combinations exist to this day, with varying degrees of success.
Grazing dairies have a distinct potential advantage in that they provide a relatively low-cost source of dry matter and nutrients over a significant part of the year, if managed correctly. Over the years, grazing dairy producers have become astute at developing management plans and selecting forage varieties or combinations of varieties that accomplish several criteria:
- They are adapted to the area where the farm is located.
- They are resilient under a variety of environmental and moisture conditions.
- They tolerate different degrees of grazing pressure.
- They provide adequate volumes of forage.
- They can also be utilized as hay or silage sources.
- They provide a significant amount of readily digestible nutrients upon which a total nutrition program can be based.
The two greatest challenges concerning the forages used in grazing dairies are the variation in nutrient density and digestibility from day to day and week to week, and the variation in environmental factors – primarily moisture conditions.
In an effort to maintain a balanced diet, regular sampling and forage testing must happen so supplemental feeds can be modified as forages change.
The perfect forage
Grazing dairies are found all over the U.S., in fact, all over the world. Considering the variation in locations, soils, moisture conditions, soil types and quality, the perfect forage for grazing-based dairy production is elusive. There are no perfect forages. There are more optimal grasses or legumes in every location, depending on many circumstances.
Fortunately, a great deal of research has been conducted in many areas that have helped identify more optimal forage types in any area, soil type or environmental condition. One of the first things the producer must do is examine some of this work to begin understanding the options available.
Another consideration is the use of perennial forages versus annuals versus a combination. Again, plant species should be considered that provide digestible nutrient levels, particularly the fiber components and proteins. In general, most plant species will be higher in degradable and soluble proteins.
Pasture management is key
Some points to keep in mind:
Rotate pastures. Manage the forage rotation for plant rest and regrowth. In summer, a rest period of about 30 to 36 days is required for most plants. Since most grasses regrow from the tillers close to the soil surface, leave 3 to 4 inches remaining after grazing species such as bermudagrass, orchardgrass or fescue. Shorter grazing will increase the time needed for regrowth.
It will decrease survivability of the plants, particularly during low moisture periods, and will reduce nutritional value of the plants. Legumes such as alfalfa and clovers regrow from the carbohydrates stored in the roots, allowing for closer grazing. Agronomists recommend grazing the plants more closely in pastures where the producer wants to encourage legume growth. Conversely, if a grass base is desired, graze the plants higher.
Focus on grazing to maintain plants in a vegetative state. To maximize digestibility, remember: Vegetative plants contain lower fiber levels, and the fiber is more digestible compared to more mature plants. Vegetative plants also contain more starch, sugars, energy and protein.
This will reduce the levels of supplemental concentrate needed to support higher milk yields. As plants mature, lignin increases, which reduces digestibility in the rumen. This reduces energy concentration of the forage and dry matter intake (along with reduced milk yield and increasing the need for more supplemental forages or concentrates).
Depending on time of year and growth circumstances, dairy cows graze about eight hours per day. In general, the heaviest grazing periods are in the early morning and later in the evening. Cows will selectively graze forage types. (Legumes are often preferred over grasses.) Initially, the top part of the plant is consumed, which contains the highest concentration of nutrients.
Secondly, the middle of the plant is grazed, where the nutrients are somewhat lower. The lower part of the plant is higher in stem and fiber (less digestibility and lower critical nutrient). Grazing management that requires animals to consume most of the plant in a single grazing pass results in more even consumption of nutrients found in the plant.
Design forage and grazing programs to provide high-quality forage consistently. Use stored forages when high-quality grazable forages are not available in quantities that match the dairy herd’s nutrient needs. Plant species such as alfalfa, sudangrass, pearl millet and warm-season perennials will grow during summertime temperatures and in full sun radiation.
BMR varieties of sudangrass improve digestibility because they contain less lignin. With sudangrasses, grazing should be avoided until plants are 24 inches tall or if they have been drought- or cold-stressed to reduce the risk of prussic acid poisoning. Winter annuals can create grass tetany issues. The producer should be aware of plant species irregularities that can create problems.
As with any feeding system, dry matter intake is critical. Dry matter intake on grazed forages is determined by bite rate, grazing time and bite size. While there is much variability, cows need to be able to consume a mouth full of feed from pasture plants to optimize forage intake.
Water is also critical and directly affects dry matter intake. Provide plenty of cool, clean water in each grazing area. Dairy cows producing 50 pounds per day of milk drink about 25 gallons per day of water when the ambient temperature is 60ºF. At 90ºF, water intake increases to 30 gallons per day.
Provide adequate shade during warmer months. Also, rotation of shade areas is important to prevent environmental mastitis.
- Pasture plants contain highly rumen-degradable protein. These plants are also low in sugars and starch. In diets high in pasture forages, high milk urea nitrogen is common. Adding starch-based concentrates and sugar sources allows rumen bacteria to capture more of the plant protein (ammonia). This can help milk yields and milk protein while decreasing milk urea nitrogen levels.
Grazing programs are easily more complex to manage when compared to other feeding programs. However, economics, performance and longevity benefits are commonly recognized for these programs. Making good decisions concerning forage varieties to establish and graze, as well as good management, is critical for long-term success.
PHOTO: Grazing dairies require close attention to forage types and grazing management to achieve the nutrition level required for milk production. Courtesy photo.
Dr. Steve Blezinger is a management and nutritional consultant with an office in Sulphur Springs, Texas. Email Dr. Steve Blezinger or call at (903) 352-3475. Follow him on Facebook at www.facebook.com/reveille.concepts
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