Submitted to: Conference on Rumen Function
Publication Type: Abstract Only
Publication Acceptance Date: 2/10/2003
Publication Date: 4/10/2003
Citation: RUSSELL, J.B., GARMER, R.M. RUMINAL HISTAMINE PRODUCTION, LAMINITIS AND ALLISONELLA HISTAMINIFORMANS GEN. NOV., SP. NOV.. CONFERENCE ON RUMEN FUNCTION. 2003. V. 1. P. 16.
Technical Abstract: Histamine appears to be a key factor in bovine laminitis. In 1950's, Dougherty noted that histamine could accumulate in ruminal fluid, and shortly thereafter, Rodwell isolated histidine decarboxylating lactobacilli. It was assumed that lactobacilli were responsible for ruminal histamine accumulation, but our ruminal histidine enrichments produced histamine even if carbohydrates were not added. The isolates were obligate histidine decarboxylating, Gram-negative, monensin-resistant, ovoid-shaped cells. 16s rRNA gene sequencing indicated that they were most closely related to low G+C Gram-positive bacteria (firmicutes), but similarities were less than 94%. Because the most closely related bacteria (Dialister pneumonsintes, Megasphaera elsdenii and Selenomonas ruminantium) did not produce histamine, we propose a new genus and species, Allisonella histaminiformans. Dairy cows fed a commercial dairy ration had large populations (>106 cells per ml) of A. histaminiformans, but A. histaminiformans could not be isolated from cattle fed diets consisting only of hay. When stationary phase A. histaminiformans MR2 cultures were serially diluted into autoclaved ruminal fluid from cattle fed a hay, histamine was not detected at dilutions greater than 10-2 even if histidine was added. In contrast, histamine was detected in the 10 -9 dilution if the autoclaved ruminal fluid was obtained from cattle fed the commercial ration and supplemented with histidine. The commercial ration contained large amounts of alfalfa and corn silages, and water-soluble silage extracts stimulated the growth of A. histaminiformans MR2 in vitro. Alfalfa silage extract was at least 8-fold more stimulatory than the corn silage extract, and extract from only 5 mg of alfalfa dry matter promoted maximal histamine production in 1 ml of culture medium. Because non-ensiled alfalfa did not stimulate histamine production nearly as much as the alfalfa silage, the factor that stimulates the growth of A. histaminiformans appears to be a product of silage fermentation.