Submitted to: American Society of Animal Science
Publication Type: Abstract only
Publication Acceptance Date: 4/2/2003
Publication Date: 7/1/2003
Citation: BURKE, J.M., ROSENKRANS, C.F., RORIE, R.W., GOLDEN, C., APPLE, J.K. 2003. REPRODUCTIVE RESPONSES AND CARCASS CHARACTERISTICS OF RAM LAMBS FED ENDOPHYTE-INFECTED TALL FESCUE. AMERICAN SOCIETY OF ANIMAL SCIENCE. 81(Suppl. 1):91-92. Interpretive Summary:
Technical Abstract: The objective of this study was to examine the influence of endophyte-infected tall fescue on reproductive development and function and carcass characteristics of ram lambs. Hampshire and Suffolk rams, 214 d of age, were fed individually a diet of endophyte-free (EF; n = 8) or infected (EI; n = 9) fescue seed (34% of diet; 4.8 g/g ergovaline) for six weeks. Intake was similar between treatments and averaged 2.7% BW (33.7 g ergovaline/kg BW). Daily high temperature ranged between 16 and 27 degrees C. Data were analyzed using the mixed models, repeated measures procedure of SAS and heterogeneity of regression. Signs of fescue toxicosis in EI fed rams included increased rectal temperature (treatment x day, P < 0.001, R sq = 0.11), increased respiration rate at higher ambient temperatures (treatment x day, P < 0.003, R sq = 0.07), and reduced serum concentrations of prolactin (treatment x day, P < 0.001). Body weight of EI fed rams tended to decrease after 36 d of feeding (-3.0 vs 0.51 kg; P < 0.07); BCS was similar between treatments throughout the trial. Serum concentrations of testosterone were greater in EI compared with EF fed rams (treatment x day, P < 0.005, R sq = 0.08). Spermatozoa concentration tended to be greater in EF compared with EI fed rams after 43 days of feeding (P < 0.07). Rate of forward movement of spermatozoa tended to be greater in EF compared with EI fed rams between Days 15 and 29 of feeding (treatment x day, P < 0.08). Scrotal skin temperature, scrotal circumference, semen volume, percent sperm motility, and percent abnormal sperm were similar between treatments. Weights of reproductive and vital organs, carcass cutability and quality characteristics were similar between EF and EI fed rams. Feeding of EI fescue seed to ram lambs led to decreased concentrations of spermatozoa in semen and increased serum concentrations of testosterone, perhaps due to decreased steroid clearance rate.