Location: Forage-animal Production ResearchTitle: Effect of endophyte-infected tall fescue seed on ruminal metabolism and physiology in Angus steers) Author
Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract only
Publication Acceptance Date: 3/8/2013
Publication Date: 7/8/2013
Citation: Kim, D.H., Klotz, J.L., Harmon, D.L. 2013. Effect of endophyte-infected tall fescue seed on ruminal metabolism and physiology in Angus steers. J. Anim. Sci. Vo. 91, E-Suppl. 2:522-523. Interpretive Summary:
Technical Abstract: This study was conducted to evaluate the effect of fescue toxicosis on changes in rumen physiology and metabolism. Eight ruminally cannulated Angus steers (BW = 548 ± 33 kg) were blocked in pairs based on BW and randomly allocated to 4 blocks. The steers were fed alfalfa cubes at 1.5 × NEm and dosed (1 kg/d) with ground endophyte-infected tall fescue seed (E+; 4.45 mg ergovaline/kg DM) or endophyte-free tall fescue seed (E-) via rumen cannula once daily for 21 d. On d 14, rumen fluid was collected prior to feeding and every 2 h for a subsequent 8 h period. Rumen contents were removed prior to the morning feeding on d 16 for evaluation of ruminal fill, and then the rumen contents were returned to the rumen with a probe for continuous monitoring of ruminal pH, temperature and pressure. Dry matter intake was not different (P = 0.293) between treatments (82.20 ± 1.05 and 79.80 ± 1.38 g of DM/BW0.75 for E- and E+, respectively), whereas rumen content DM was higher (P = 0.060) for E+ than E- (16.26 ± 2.26 and 12.97 ± 1.72 g of DM/kg of BW, respectively). Total VFA, acetate, propionate, and butyrate concentrations, and acetate:propionate ratio were higher for E+ than E- (Table 1). Likewise, ammonia concentration was higher (P = 0.058) for E+ dosing. Ruminal pH and temperature were not affected by treatment (P = 0.657 and 0.499, respectively), whereas ruminal pressure was lower (P < 0.001) for E+ dosing. Serum prolactin concentration was lower (P < 0.001) for E+ (0.40 ± 0.02 and 25.49 ± 2.61 ng/mL for E- and E+, respectively). Data in this study indicate that endophyte-infected tall fescue seed may contribute to depression of ruminal VFA absorptive function related to ruminal motility changes.