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ARS Home » Midwest Area » Lexington, Kentucky » Forage-animal Production Research » Research » Research Project #441844

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

Location: Forage-animal Production Research

Project Number: 5042-32630-004-005-N
Project Type: Non-Funded Cooperative Agreement

Start Date: Mar 1, 2022
End Date: Feb 28, 2027

Experiment 1: A grazing experiment to determine how the addition of different isoflavone-containing legumes ruminal fermentation and consequently weight gain efficiences in growing steers grazing mixed grass pastures. Experiment 2: Grazing experiments will determine the impact of red clover leaf containing mineral on reproductive health and performance in beef cows/heifers and heat stress and growth of growing steers grazing endophyte-infected tall fescue (E+ TF) pastures.

APPROACH: Experiment 1: A grazing experiment will be conducted with 72 beef steers and 12 rumen-fistulated Holstein steers per year that will be assigned to 12, 1.0-ha pastures of orchardgrass, Kentucky bluegrass, and endophyte-free tall fescue. Four treatments will be evaluated: 1) pasture + dried distiller's grains (DDG) control; 2) pasture + DDG + red clover hay (~15% of total intake, calculated based on the concentration of total isoflavones utilized in previous experiments with a 15% red clover hay treatment); 3) pasture + DDG + alfalfa hay (equal in weight to red clover hay treatment); and 4) pasture + DDG + soybean meal (equal in weight to red clover hay treatment). All treatments will made to be isonitrogenous via the inclusion of DDG. Grazing will be initiated in mid-April and end in early July. Average daily gain will be measured for the beef steers and rumen fluid will be collected at 2-week intervals from rumen fistulated steers for evaluating rumen fermentation characteristics. Experiment 2: Grazing experiments will be conducted with 30 beef steers or 30 heifers/cows per year that will graze 12, 3.0 ha sub-divided pastures of toxic endophyte-infected tall fescue. Each grazing group will be assigned to either a conventional loose mineral control or the same conventional mineral amended with 20% w/w red clover. Grazing will be initiated in mid-April and end in late-October. Reproductive ultrasound scans (heifers/cows only), breeding statistics (heifers/cows only), average daily gain, body condition scores, respiration rates and haircoats will be collected. Jugular blood will be collected every 30-d for blood urea nitrogen and prolactin.