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ARS Home » Midwest Area » Lexington, Kentucky » Forage-animal Production Research » Research » Research Project #431460

Research Project: Approaches to Minimize the Occurence of Fescue Toxicosis in Livestock

Location: Forage-animal Production Research

Project Number: 5042-32630-003-05-N
Project Type: Non-Funded Cooperative Agreement

Start Date: Mar 1, 2017
End Date: Feb 28, 2022

Objective:
Experiment 1: A grazing experiment using mixed grass pastures will evaluate the effects of isoflavones contained in red clover hay on steer weight gain efficiency and rumen fermentation characteristics. Experiment 2: A grazing experiment will determine if isoflavones contained in red clover that is overseeded into toxic endophyte-infected tall fescue pastures can mitigate fescue toxicosis and enhance both steer weight gain performance and well-being.

Approach:
Experiment 1: A grazing experiment will be conducted with 36 beef steers and 12 rumen-fistulated Holstein steers that are assigned to 12, 1.0-ha pastures of orchardgrass, Kentucky bluegrass, and endophyte-free tall fescue. Pastures will be assigned treatments of pasture-only, pasture plus dried distillers grains (1.4 kg/steer/day), and low (0.9 kg/steer/day) and high (1.8 kg/steer/day) amounts of red clover with dried distillers grains such the diets are isonitrogenous with the the dried distillers grains only treatment. Grazing will be initiated in mid-April and end in late June. Average daily gain will be measured for the beef steers and rumen fluid will be collected at 2-week intervals from rumen fistualated steers for evaluating rumen fermentation characteristics. Experiment 2: A grazing experiment will be conducted with 20 beef steers that will be used as tester animals and 32 that will be treated as put-and-take grazers to maintain consistent forage availabilities across the four 3.0-ha pastures of toxic endophyte-infected steers that will be either with or without overseeded red clover. Grazing will be initiated in mid-April and end in late June. Average daily gain will be measured and jugular blood will be collected at the start and finish for measuring blood urea nitrogen. All testers will be placed in pens and fed ad libitum corn silage and soybean meal for monitoring blood flow using Doppler ultrasonography. Five steers will also be penned that will have grazed bermudagrass as non-toxic control animals.