Articles on forages, animals, and grazing systems
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Extension Forage Specialist
University of Kentucky
Phone: (859) 257-3358
Fax: (859) 323-1952
The Western Kentucky Grazing network held their second pasture walk of the 2012 grazing season on May 30, 2012 at Menno Beiler’s organic dairy near Trenton, KY. This farm, which has been an organic dairy for four years, milks around 50 cows in a tie-stall barn. Menno raises his own replacement heifers. Organic Valley, a farmer-owned cooperative which purchases milk from Menno, requires that cows get 30% of their dry matter intake from pastured forages. This dairy rotationally grazes a large variety of forages. Cool-season grasses grazed include Italian ryegrass, orchardgrass, timothy, tall fescue, red and white clover, and alfalfa. A sorghum X sudangrass hybrid is utilized for summer grazing while small grains, such as triticale, are often seeded for fall grazing. There are multiple paddocks set up for rotation. Narrow lanes are utilized for easy movement of the cows to and from the barn and to conserve land for grazed forages. Some paddocks are irrigated using a sprinkler system when necessary.
As the group of almost 30 local producers walked through the pastures, Dr. Ray Smith, UK extension forage specialist, answered questions and discussed practices used on the farm. A root of an alfalfa plant and red clover plant were dug up to compare root systems and root health. Dr. Smith explained the growth of an alfalfa root and displayed how the deep-growing taproot increases this species drought tolerance. Both roots were cut length-wise to demonstrate a white, healthy root versus an older root with traces of root rot.
One of the pastures contained large amounts of Johnsongrass which the cows selectively grazed. Dr. Smith discussed the possibility of this grass and others in the sorghum family causing prussic acid or cyanide poisoning. Although these forages can supply high quality feed throughout the hot summer months, it is important to use caution to decrease risk. The likelihood of prussic acid poisoning increases when plants are stressed, such as after a frost or during a drought. Young shoots may also contain high levels of cyanide-producing compounds. It is suggested to wait 10-14 days after non-killing frost with no additional frost action before grazing these plants and do not graze after a killing frost until plant material is dry (the toxin usually dissipates within 72 hours.) Do not graze at night when frost is likely. High levels of toxins are produced within hours after frost occurs. Dr. Smith used cyanide test strips to test for cyanide levels. Ask your county agent for more information on prussic acid poisoning and testing forages.
Dr. Donna Amaral-Phillips talked about how to manage heat stress in dairy cattle in pasture-based systems. Providing shade and cool source of water is important to helping cattle cope with the heat. Shade trees or structures need to be rotated to prevent cows from getting mastitis.
The next Western KY pasture walk is scheduled for September 26, 2012 at Wayne Burkholder’s dairy farm in Christian County from 9:30 AM till 2:30 PM. These pasture walks are part of the Master Grazer Educational program and are supported from funds through the KY Agricultural Development Board.
Paddock layout and size, placement of water and mineral feeders, and management practices can greatly affect uniformity of grazing. Research has shown the shape and size of an individual paddock influences grazing. Square paddocks will be grazed more evenly than rectangular or other shaped paddocks. If possible, water should not be placed more than 800 feet from any area of the paddock to improve distribution of grazing animals and manure. Regularly moving mineral feeders may also increase uniformity of grazing and reduce severity of soil compaction in these areas while increasing manure distribution.. The time the animals will be in the paddock needs to be adjusted to account for forage availability, paddock size, and stocking density to ensure uniform grazing.
Mowing pastures and/or using a more intensive rotational grazing system where a larger number of animals are in a paddock for a shorter amount of time may also help attain this goal. In less intensive rotational or continuous grazing systems animals are more likely to selectively graze the more palatable forages which can increase undesirable plants. When plenty of quality forages are available, giving the animals the ability to selectively graze may have benefits of increased animal production but will decrease forage utilization. Uniform grazing is an important part of managing pastures to maximize forage quality and production.
Comparison of white, healthy root (on right) versus an older root with traces of root rot (left).