Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 21, 2004
Publication Date: July 24, 2004
Citation: Burke, J.M., Brauer, D.K., Looper, M.L. 2004. Use of novel endophyte-infected tall fescue for cow-calf production in arkansas. American Society of Animal Science Annual Meeting. 82 (Supplement 1):91. Technical Abstract: The objective was to examine pregnancy, calving rates, and calf growth in cow-calf pairs on endophyte-free (EF; Kentucky 31), novel endophyte-infected (NE; Jesup), and endophyte-infected (EI; Kentucky 31) tall fescue. Angus and Angus x Hereford cows grazed EF, NE (n = 20/16 ha), or EI (n = 30/24ha) starting November 2001 through July 2003. To prevent overgrazing, NE cattle were removed from July to November 2002 and in May 2003. Hay was supplemented as needed over winter. Pastures were fertilized with an equal amount (63.9 kg/ha) of N, P and K in late February both years. Cows were bred in May for a 60 day breeding period. Cows were removed if not pregnant at weaning or lost a pregnancy or calf after calving and replaced with a comparable pregnant cow or cow-calf pair that had previously grazed bermudagrass (for EF and NE groups) or EI (for EI group) fescue. Forage yields were determined using exclusion cages (n = 3/pasture) between February and December 2003. Yield of EI was greater than that of EF or NE from April to June and EF and EI forage yield was greater than that of NE in August (forage x month, P < 0.02). Cows grazing EF fescue gave birth to heavier calves than those grazing EI (P < 0.04) and NE calf weights were similar to EF and EI weights (EF, 38.3 ± 0.7; NE, 36.7 ± 0.7; 36.3 ± 0.6 kg; P < 0.10). Calf weights were similar in May 2003 among forage groups (P = 0.15); however, between May and July 2002, EF and NE calves were heavier than EI calves (forage x time, P < 0.001). At weaning (early October 2002) pregnancy rate, determined by transrectal ultrasound, was greater in NE than EI cows (P < 0.03) and similar between EF and EI cows (EF, 70.9 ± 9.7; NE, 96.2 ± 9.8; 67.8 ± 8.6%; P < 0.07). By calving, rates were similar among forage groups (EF, 70.0 ± 10.7; NE, 80.2 ± 10.9; 63.2 ± 9.5%; P = 0.35). In summary, calf production from cows grazing NE fescue was greater than that of cows grazing EI fescue. However, its use as a summer forage at a similar stocking rate (1 cow/0.8 ha) is limited in Arkansas because of overgrazing potential.