Date of Award
Master of Science (MS)
Plant and Environmental Science
Andrae, John G
Duckett , Susan K
Pratt , Scott L
Research was conducted to determine the effect of tall fescue and alternative management regimens on reproduction in replacement beef heifers. Angus _ Simmental heifers (n = 48; 318 ± 4.99 kg initial BW) stratified by weight and pubertal status were assigned to one of three replicated grazing treatments: (1) toxic endophyte-infected tall fescue (TF); (2) toxic endophyte-infected tall fescue with a soybean oil supplement (TFO); or (3) mixed winter annual species (cereal rye, annual ryegrass, crimson clover and hybrid turnip) (M). Tall fescue endophyte infection level was between 74 and 94%. Pastures were grazed from December 12 to April 24. Oil was supplemented once daily at a rate of 1 g/kg BW with a soy hull (4 g/kg BW) carrier. Heifers grazing M had higher ADG than TFO which was higher than TF (P < 0.01). Total standing heats and mounts per standing heat did not differ among treatments (P = 0.89 and P = 0.21). Conception rate did not differ among treatments. Serum cholesterol (P < 0.01) and total fatty acids (P < 0.01) were greater in TFO than in TF and M heifers. Serum concentrations of 16:0, 18:0, 18:1, 18:2 and 20:4 were greater in TFO heifers than in the TF and M treatments (P < 0.01) whereas 18:3 concentration was greatest in the M heifers (P < 0.01). While diet affected gain, prolactin, serum fatty acid and cholesterol concentrations, no differences were observed in heifer estrus measures or conception rates.
Miller, Margaret, "MANAGEMENT STRATEGIES TO IMPROVE DEVELOPMENT OF REPLACEMENT HEIFERS UTILIZING TALL FESCUE-BASED SYSTEMS" (2009). All Theses. 539.