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
Tall fescue covers 5 million acres of hay meadows and pastures in Kentucky and has been the predominant forage in the state for over 50 years. Popularity of the grass is due to its productivity, persistence, and low cost of management. Unfortunately, a fungal endophyte that infects most plants of tall fescue produces ergot alkaloid toxins that cause a toxicosis in cattle and other grazing livestock. Fescue toxicosis may reduce reproductive performance of cow herds and weaning weights, and drastically reduce post-weaning weight gain and overall thriftiness. Consequently, fescue toxicosis is estimated to cost the U.S. beef industry approximately 1 billion dollars each year.
Clovers can be interseeded into endophyte-infected tall fescue to boost cattle performance and dilute ergot alkaloids in the cattle diet, but adverse weather conditions and patterns, lack of grazing management, or the use of excessive stocking rates will reduce the reliability of clovers as contributors to cattle diets. An alternative to clovers is to feed co-product feeds to provide a similar effect as clovers. Grain concentrates may also be fed, but grain prices have escalated in recent years and made them less feasible for feeding pastured cattle. This has turned cattlemen to cheaper co-product feeds, such as soybean hulls (SBH), cottonseed hulls (CSH), or dried distillers grains (DDG). An increased demand for co-product feeds has increased their prices, but they still remain a cost-effective alternative to grain-based concentrates. There are a multitude of co-product feeds besides SBH, CSH, and DDG that are available to cattlemen; for example, wet distillers grains, dried brewers grains, and bakery wastes. Many of these co-product feeds are sold at a low (or no) cost directly from the processing plant. However, logistics and cost of transporting co-product feeds to the farm must be considered as farm distance from the processing plant increases. There has been less research on the nutritive value and feeding management of many of the co-product feeds.
Co-product feeds can be fed in cost effective quantities to cattle grazing toxic endophyte-infected tall fescue while providing some dilution of the ergot alkaloids. We have conducted research with beef steers at the USDA-ARS Forage-Animal Production Research Unit (FAPRU) to determine if daily feeding of pelleted SBH at 0.8 to 1.0% of bodyweight (a 500 lb calf is fed 4 to 5 lbs) per day on toxic endophyte-infected tall fescue can increase average daily gain and reduce the severity of fescue toxicosis. Two experiments were conducted separately in the spring and summer. In both experiments, steers fed SBH had average daily gains that were over 30% greater those not fed SBH. A higher percentage of the steers fed SBH also shed their winter hairs and had sleeker hair coats than steers not fed SBH. These results indicated that feeding SBH may reduce the severity of toxicosis, increase cattle growth rates and increase marketability of calves off fescue pastures.
Preliminary research conducted by Dr. Eric Vanzant, a ruminant nutritionist with the UK Animal and Food Sciences Department, demonstrated that DDG can provide substantial increases in the daily weight gain of steers grazed on toxic tall fescue. He will conduct more experiments to determine the optimum amount of DDG to feed for maximum cost effectiveness in increasing average daily gain and reducing the severity of fescue toxicosis.
It cannot be concluded that dilution of ergot alkaloids with consumption of co-product feeds or clovers can alleviate fescue toxicosis because it is apparent that cattle will still consume some ergot alkaloids, and recent research conducted by Dr. Jimmy Klotz, a ruminant physiologist at FAPRU, provided evidence that ergot alkaloids accumulate in tissues of cattle. Nonetheless, co-product feeds may reduce the amount of consumed ergot alkaloids to an extent that allows for low accumulation of alkaloids in the cattle.