In vitro and in vivo ruminal and physiological responses to endophyte-infected tall fescue

• Published in: Journal of dairy science 1993-02, Vol.76 (2), p.555-563
• Main Authors: Westendorf, M. L, Mitchell, G. E., Jr, Tucker, R. E, Bush, L. P, Petroski, R. J, Powell, R. G
• Format: Article
• Language: English
• Subjects: acremonium; Acremonium - growth & development; alcaloide de l' ergot de seigle; Alkaloids - metabolism; Animals; Biological and medical sciences; Cattle; Diet; digestibilidad; digestibilite; digestibility; Digestion; ergot alkaloids; ergotinas; experimentacion in vitro; experimentation in vitro; fermentacion; fermentation; festuca arundinacea; Fundamental and applied biological sciences. Psychology; in vitro experimentation; In Vitro Techniques; ovin; ovinos; Poaceae - metabolism; Poaceae - microbiology; rumen; Rumen - metabolism; Sheep; Vertebrates: digestive system
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(93)77375-0

Relationships between alkaloid compounds in endophyte-infected tall fescue and ruminal metabolism were studied in two experiments. In the first experiment, different combinations of the pyrrolizidine alkaloids, N-formyl and N-acetyl loline, were incubated with ruminal fluid for 0, 24, or 48 h. Rate of disappearance of N-formyl and N-acetyl loline increased over time. After 48 h, disappearance of N-formyl loline and combinations of N-formyl and N-acetyl loline was greater than N-acetyl loline. Significant amounts of N-formyl and N-acetyl loline were metabolized and converted to loline. In the second experiment, abomasally cannulated sheep were fed increasing amounts of endophyte-infected feed to compare diet digestibility, alkaloid metabolism, and physiological responses. Total tract DM digestibility was greatest for the endophyte-free diet, as were ruminal and total tract ADF, ruminal NDF, and total tract CP digestibilities. N-formyl and N-acetyl loline recoveries averaged 5% from abomasal contents and 0% in feces. Sixty-eight percent of the pyrrolizidine alkaloids recovered in abomasal contents had been metabolizable to loline. Ergot alkaloids administered in the diet were recovered (50 to 60%) in the abomasal contents, but recovery was only 5% in fecal collections. No significant differences occurred in the physiological parameters measured. Results indicate that response to endophyte-infected tall fescue may be influenced by ruminal metabolism.