Selective enumeration of Fusobacterium necrophorum from the bovine rumen

Abstract

A culture medium containing lactate as the sole energy source and antibiotics (bacitracin, gentamicin, and streptomycin) was used for selection and enumeration of Fusobacterium necrophorum from bovine ruminal contents. F. necrophorum growth was determined by indole production, and enumeration was performed by the most-probable-number technique. The number of F. necrophorum cells in cattle fed a 100% forage diet was 7 x 105/g of ruminal contents. The number increased (P < 0.05) 10-fold after the diet was changed to 85% corn grain. Fusobacterium necrophorlum, the primary etiologic agent of bovine hepatic abscesses, is a normal inhabitant of the bovine rumen (16). Hepatic abscesses in cattle are related to feeding of high-grain diets (9, 10). Rapid fermentation of grain in the rumen and the consequent accumulation of organic acids, particularly lactate, result in ruminal acidosis and rumenitis. F. necrophorum penetrates the damaged rumen epithelial wall, reaches the liver via the portal circulation, and causes abscesses (19). F. necrophorum has been detected in or isolated from bovine ruminal contents and ruminal lesions by an immunofluorescence technique (7), by culture methods (23, 26), and by injecting ruminal fluid intraperitoneally into rats (3). However, quantitation of F. necrophorum in ruminal contents is hampered by the lack of a selective medium. Therefore, we developed a method for selectively enumerating F. necrophorum in bovine ruminal contents. A modified lactate (ML) medium was used for selection and enumeration of F. necrophorum from bovine ruminal contents. The composition of ML broth (per liter) was as follows: 10 g of DL-lactate (United States Biochemical Co., Cleveland, Ohio), 10 g of tryptone (Difco Laboratories, Detroit, Mich.), 1 mg of hemin (Eastman Kodak Co., Rochester, N.Y.), 10 ml of vitamin B mixture (20), 38 ml each of mineral I (0.

Liver abscesses in feedlot cattle: a review.

“…However, this concentration is influenced by the diet. The number of F. necrophorum cells in the rumen increased after the diet was changed from roughage ( 7 × 10 5 /g) to high-grain ( 3 to 7 × 10 6 /g; Tan et al, 1994c). Because F. necrophorum uses lactate as the major substrate and not any sugars, the increased population in cattle fed the high-grain diet probably was due to an increased lactate availability in the rumen.…”

“…This species generally does not ferment any carbohydrates, although some strains ferment glucose weakly; its major energy substrate is lactic acid, which is fermented mainly to acetate, butyrate, and small amounts of propionate (Lechtenberg et al, 1988). It also produces a number of proteases (Nakagaki et al, 1991;Tan et al, 1994c).…”

Effects of feeding polyclonal antibody preparations on rumen fermentation patterns, performance, and carcass characteristics of feedlot steers

“…Vials were introduced into an anaerobic glove box (Coy Laboratories Inc., Grass Lake, MI) containing an O 2 -free atmosphere of CO 2 (98%) and H 2 . Vials were vortexed inside the glove box, and a 20-µL aliquot was transferred to each of 3 wells in a 96-well microtitration plate containing 180 µL of minimal medium (Russell et al, 1981) or modified lactate medium (Tan et al, 1994) for quantification of S. bovis or F. necrophorum, respectively. Serial 10-fold dilutions were performed in triplicate to determine the most probable number (MPN) of S. bovis or F. necrophorum per milliliter of ruminal fluid.…”

Effect of virginiamycin on ruminal fermentation in cattle during adaptation to a high concentrate diet and during an induced acidosis.

“…populations were enumerated using Enterococcosel (BBL Microbiology Systems, Cockeysville, MD) and MRS (Difco Laboratories, Detroit, MI) media, respectively (Slyter et al, 1968;Anderson et al, 1987). Fusobacterium necrophorum concentrations were determined according to the most-probablenumber ( MPN) technique using modified lactate broth (Tan et al, 1994).…”