Date of Graduation

Spring 2015


Master of Natural and Applied Science in Agriculture


College of Agriculture

Committee Chair

Gary Webb


The purpose of this study is to analyze cow/calf production, measured by calf weaning weight and summer conception rates of females grazing endophyte infected (E+) tall fescue treated with the chemical growth regulator Chaparral (Dow AgroScience, LLC). Data were collected from two private cattle ranches in southwest Missouri. At one, 132 Brangus first parity females were bred in June 2013, calved in the spring of 2014, and rebred in the summer of 2014. Females were placed on one of six E+ tall fescue pastures either treated with Chaparral or GrazonNextHL (Dow Agrosciences, LLC) for both years. Along with Pastures were also analyzed for tiller ergovaline and ergovalinine concentration, seed head suppression, and species composition. Pastures were monitored for available forage biomass throughout the 2014 grazing season. At the second ranch 606 Angus females and 501 Angus calves were analyzed over the 2014 grazing season for both calf 205 d adjusted WW and female pregnancy rates on E+ tall fescue pastures treated with Chaparral or no Chaparral. In 2014, 205 d adjusted WW tended to be higher at both ranches while pregnancy rates were higher. In 2013 alone, pregnancy rates of Brangus females were not different, but pregnancy rates were different between treatments across 2013 and 2014. For Brangus females, available forage biomass and alkaloid concentrations were reduced in Chaparral treatments, while seed head presence varied greatly across treatments. Chaparral treatments increased grass-weed and sedge species and reduced un-identifiable plant residues in pastures. In conclusion, Chaparral can increase profitability per acre in fescue based beef cattle production.


tall fescue, seed head suppression, beef cattle, ergovaline, cow/calf

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© William Francis Boyer

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